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Euonymus fortunei

• INTRODUCTORY
• DISTRIBUTION AND OCCURRENCE
• BOTANICAL AND ECOLOGICAL CHARACTERISTICS
• FIRE EFFECTS AND MANAGEMENT
• MANAGEMENT CONSIDERATIONS
• APPENDIX: FIRE REGIME TABLE
• REFERENCES

INTRODUCTORY

AUTHORSHIP AND CITATION FEIS ABBREVIATION NRCS PLANT CODE COMMON NAMES TAXONOMY SYNONYMS LIFE FORM FEDERAL LEGAL STATUS OTHER STATUS
	Photo by Keith Langdon, National Park Service, Bugwood.org

Although not distinguished in local floras, Kartesz [33] recognizes 2 varieties in North America:
    Euonymus fortunei (Turcz.) Hand.-Maz. var. fortunei
    Euonymus fortunei (Turcz.) Hand.-Maz. var. radicans (Sieb. ex Miq.) Rehd.

A review by Dirr [17] describes another variety in the United States, E. f. var. coloratus, which he says is often listed as the cultivar 'Coloratus'. Dirr [17] describes 51 cultivars of E. fortunei. A review by Blakelock [2] describes several varieties and forms of E. fortunei, occurring mostly in Asia or as cultivars, distinguished primarily by leaf characteristics. The Flora of China states "Numerous taxa have been named within the E. fortunei complex but many of these refer to cultivated plants and are best treated as cultivars" [76]. In this review, E. fortunei is referred to as "winter creeper", varieties are referred to by scientific name, and cultivars, when identified as such in the literature, are referred to by cultivar name in single quotation marks (e.g., 'Emerald and Gold').

SYNONYMS:
for Euonymus fortunei var. radicans [33]:
    Euonymus radicans [50]

LIFE FORM:
Liana-shrub

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
Information on state-level noxious weed status of plants in the United States is available at Plants Database.

DISTRIBUTION AND OCCURRENCE

• GENERAL DISTRIBUTION
• HABITAT TYPES AND PLANT COMMUNITIES

GENERAL DISTRIBUTION:
Winter creeper is native to China ([76], reviews by [1,62,73]) and was introduced to North America as an ornamental ground cover in 1907 (reviews by [1,29,52,54]). It has escaped cultivation and established in scattered areas in the central and eastern United States (reviews by [1,52,54]). According to distribution maps provided by Plants Database, in Canada winter creeper occurs only in Ontario, and in the United States it occurs from Maryland to Wisconsin, south to Georgia and Mississippi (with the exception of West Virginia), and west to Missouri and Nebraska. The distribution of E. f. var radicans is identical to that of the species; while E. f. var fortunei occurs only in Maryland and Illinois [69]. Winter creeper, along with several other horticultural plant species, is susceptible to attack by a fungal parasite that is native to and occurs only in the southwestern United States and adjacent Mexico (Duffield and Jones 1998 as cited by [40]). This fungus, Texas root rot (Phymatotrichum omnivorum), may exert a strong influence on plant invasions in that region [40].

Local floras and other references report varying frequency of escape from cultivation among areas where winter creeper occurs, suggesting a scattered and disjunct pattern of distribution. Winter creeper occasionally escapes in the northeastern United States [22,42]. It was observed and described as "naturalized" along the west bank of Rock Run near Plummers Island in Maryland around 2003 [56]. It appeared "sporadically" as escapes in Ohio as of 1961 [3] and "seldom" escaped in Michigan as of 1985 [73]. It was a newly reported component of the flora in Illinois sometime between 1956 and 1978 [27], listed in only 1 county there in 1978 [47], and described as "infrequently escaped from cultivation and scattered" in 1986 [46]. A 1990 review by Hutchison [29] reports that winter creeper occurred mostly near urban centers in Illinois, with reports from several sites in the East St Louis area. It was common throughout Giant City State Park and Fern Rocks Nature Preserve in Jackson County, Illinois, and near Karnak in Pulaski County [29]. Winter creeper was not described the flora of the Carolinas (1968), but the flora states that various horticultural species of Euonymus (including winter creeper) "may persist around old homesites or may rarely escape from cultivation" [50].

Forest Inventory and Analysis (FIA) data from forests in 12 southern states indicate that winter creeper was detected in only 5 states and was most common in Kentucky and Tennessee [44]:

HABITAT TYPES AND PLANT COMMUNITIES:
Plant community associations of nonnative species are often difficult to describe accurately because detailed survey information is lacking, there are gaps in understanding of nonnative species' ecological relationships, and nonnative species may still be expanding their North American range. Therefore, winter creeper may occur in plant communities other than those discussed here and listed in the Fire Regime Table.

Winter creeper is most commonly reported as occurring near homesites and disturbed areas (see Site Characteristics) and in forests and woodlands. In its native China, winter creeper is common in woodlands, scrub, and forests [76]. In North America, it has spread into upland and lowland forests in the eastern and central parts of the United States (review by [54]). A review by Grese [24] lists winter creeper as a problem species in forest communities in the United States but not in open or wetland communities; however, it may also occur in open communities (personal communication [32], [59]) such as savannas and grasslands (personal communication [63]).

Winter creeper occurs in forests and woodlots in the Great Lakes states. It was collected in an oak woods west of Marshall, Michigan in 1984, where it evidently (based on juvenile foliage) had established from seed [73]. Winter creeper occurred in forests dominated by sugar maple and American beech in central Indiana [7], and it occurred in disturbed woodlots in Indianapolis that were dominated by maples (Acer spp.), oaks, elms (Ulmus spp.), ashes (Fraxinus spp.), and hickories. These woodlots had evidence of extensive human impact and supported several other nonnative and invasive plant species [53]. According to a review by Hutchison [30], winter creeper has spread into many types of forest in Illinois, including floodplain, mesic, and dry-mesic forests.

In the mid-Atlantic region, winter creeper may occur in oak-pine (Quercus-Pinus), oak-hickory (Quercus-Carya), and mixed mesophytic forests characterized by tree species such as American beech (Fagus grandifolia), yellow-poplar (Liriodendron tulipifera), yellow buckeye (Aesculus flava), sugar maple (Acer saccharum), white oak (Quercus alba), northern red oak (Q. rubra), and black walnut (Juglans nigra) among others (personal communication [63]). Winter creeper was occasional in mature, second-growth oak-hickory forest and edge habitat in Rock Creek Park in Washington, DC, where common canopy species included a variety of oaks (Quercus spp.), American beech, yellow-poplar, hickories (Carya spp.), and red maple (Acer rubrum) [20]. Winter creeper did not occur in Strounds Run State Park in southern Ohio in 1957, but was listed as a "naturalized alien" there in a study published in 2006. It was described as "rare": occurring in only 1 or 2 locations. It occurred on mesic ravines and/or stream terraces that were generally occupied by mixed mesophytic forests dominated by red maple, silver maple (A. saccharinum), shagbark hickory (C. ovata), American beech, green ash (Fraxinus pennsylvanica), yellow-poplar, black cherry (Prunus serotina), and northern red oak [26]. At Stones River National Battlefield in Tennessee, winter creeper occurs in the Interior Plateau chinquapin oak-Shumard oak (Quercus muehlenbergii-Quercus shumardii) forest association. These dry-mesic forests are codominated by varying proportions of shagbark hickory, Carolina shagbark hickory (Carya carolinae-septentrionalis), eastern redcedar (Juniperus virginiana var. virginiana), and sugarberry (Celtis laevigata). In addition to winter creeper, other nonnative plant species occurring in this community include Amur honeysuckle (Lonicera maackii), Japanese honeysuckle (Lonicera japonica), privets (Ligustrum sinense, Ligustrum vulgare), and tree-of-heaven (Ailanthus altissima). This forest association is considered globally rare, and most, if not all, high-quality examples have been eliminated or severely impacted by timber removal, grazing, soil erosion, and fire exclusion. Other threats include windthrow, microclimate modification from intensive silvicultural practices on adjacent uplands, forest type conversion, and herbicide use [49].

A review by Stocker and Hupp [61] suggests that winter creeper is potentially invasive in oak-hickory woodland in the southeastern United States.

Winter creeper may also occur in more open plant communities (personal communications [32,63]). Winter creeper occurred but was rare on the Potomac River Lowland in Piscataway and Fort Washington National Parks in Maryland. Here it occurred on sandy beach berms in communities dominated by calamus (Acorus calamus), narrow-leaved cattail (Typha angustifolia), and other marsh species, in areas where silver maple, green ash, and poison-ivy (Toxicodendron radicans) also occurred [59].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

• GENERAL BOTANICAL CHARACTERISTICS
• SEASONAL DEVELOPMENT
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS

Winter creeper is a perennial, typically evergreen, trailing or climbing (by aerial, adventitious roots) liana, subshrub, or shrub [1,3,22,30,46,52,73,76]. Stems are narrow [52] and minutely warty [1,52,73]. Winter creeper leaves are densely arranged on branches [76], opposite, ovate to elliptic, leathery, and vary from 1 to 2.5 inches (2.5-6.5 cm) long [1,3,46,52,54]. Leaves may be petiolate [22], with a petiole 2 to 9 mm long, but are sometimes sessile [76].

According to reviews, winter creeper seldom flowers [73], and flowers occur only on adult types [17]. Observations in Kentucky, however, indicate that winter creeper flowers and fruits consistently and prolifically from year to year (personal communication [63]). See Flower and seed production for further details. Flowers are inconspicuous [1,17,52], perfect [17,22,46], and occur in cymes [1,22,46,52] with few to several flowers [3]. Winter creeper fruits are smooth, dehiscent capsules [3,22,46], about 5 to 6 mm in diameter [76]. Its seeds are enclosed in a fleshy, colorful aril [3,17,22,73].

Winter creeper stems have abundant aerial rootlets or trailing roots [1,52] that form at nodes [46]. Aerial rootlets aid winter creeper plants in climbing vertical surfaces [1,3,73] or form independent plants by sprouting along the ground surface [1].
	Stem with aerial roots in May
	Photo by James H. Miller, USDA Forest Service, Bugwood.org

The numerous cultivars of winter creeper vary mostly in leaf size and color (reviews by [12,17,29]) but may also vary in plant size, growth form, and fruit production (review by [17]).

Growth form and population structure: Winter creeper plants can form dense groundcover [1,29,43,52] trailing to 20 or more feet (6 m) [1,29], climb 40- to 70-foot-tall (12-21 m) vertical surfaces with the aid of aerial roots [17,43,52], or grow as shrubs up to 3 feet (1 m) tall [1,29,43,52].

	When growing as a groundcover, independent winter creeper plants originate from rootlets at short intervals along procumbent stems. Established populations appear as a dense mat of vegetation (reviews by [1,12,52]) that may impede the growth of native seedlings. As a liana, winter creeper may climb rocks, trees, or other supporting structures. It may overtop trees, covering tree leaves and preventing photosynthesis (review by [52]). See Impacts for additional information.
Photo by James H. Miller, USDA Forest Service, Bugwood.org		Photo by Chris Evans, River to River CWMA, Bugwood.org

Winter creeper growth and architecture may be altered after plants are damaged. Winter creeper cultivar 'Coloratus' plants damaged by rabbits in a nursery in Arkansas in fall and winter had lower canopy cover in March than the previous November; however, plants damaged by rabbits saw a considerable regrowth of stems and leaves from March through May. New spring growth nearly tripled previous growth percentages due to the unique architecture of second-year growth, which produced lateral stems with additional leaves on existing nodes [58].

Raunkiaer [51] life form:
Phanerophyte
Chamaephyte
Geophyte

SEASONAL DEVELOPMENT:
According to a review by Bean and McClellan [1], because winter creeper is evergreen and begins growing before other vegetation emerges, it outcompetes existing vegetation for available space and resources.

In North America, winter creeper generally flowers in the summer (June to July) and produces mature fruits by fall (reviews by [12,17,43,52,54]), though flowering and fruiting may occur earlier at lower latitudes (see table below). According to a review by Dirr [17], fruits mature October to November and often persist.

Winter creeper may abscise a few leaves throughout the year, but most abscission occurs in early spring (unpublished data cited by [10]).

REGENERATION PROCESSES:
Winter creeper regenerates sexually by producing fruits that are readily dispersed by birds, and vegetatively through long branches and lateral shoots that root at the nodes and form independent plants (reviews by [1,12,52]).

Pollination and breeding system: Winter creeper flowers are perfect [17,22,46]. No additional information is available on this topic.

Flower and seed production: As of 2009 very little published information was available regarding seed production in winter creeper. According to reviews, winter creeper seldom flowers [73], and flowers occur only on adult types [17]. Observations in Kentucky, however, indicate that winter creeper flowers and fruits consistently and prolifically from year to year (personal communication [63]). In order to flower and produce seed, winter creeper must climb trees or other objects to get more sunlight. If no uprights are present, it does not obtain the liana diameter (approximately 1cm or greater) that triggers flowering (personal communication [63]). Climbing stems of winter creeper typically flower in summer and produce mature fruit in fall (see Seasonal Development). Groundcover populations seldom, if ever, flower and fruit (reviews by [12,17,54]). Because it can form extensive groundcover without developing upright, climbing stems, it probably appears that it does not readily flower in many areas (personal communication [63]).

Seed dispersal: Winter creeper seeds are equipped with arils that are readily eaten by birds and other wildlife, which then disperse the seed (reviews by [12,30,52], personal communication [63]), possibly many miles away [54]. Muhlenbach [48] recorded the occurrence of a few specimens of winter creeper (E. f. var. radicans) on one site along the railroad in St Louis, Missouri, in 1969. He notes that although this species was often cultivated as a ground cover in St Louis, there were no gardens in the vicinity [48], suggesting long-distance dispersal. Similarly, winter creeper's presence in fragmented old-growth forests in Indiana suggests some form of long-distance dispersal because it is not an agricultural weed, and these forests were bordered mostly by corn and soybean fields [7].

On an old farm site in Kentucky with large scattered trees, the understory is covered by dense growth of the nonnative invasive species multiflora rose (Rosa multiflora), winged burning bush (Euonymus alatus), winter creeper, and Oriental bittersweet (Celastrus orbiculatus). All of these species have bird-dispersed seed, suggesting that birds using the large old trees as perches "planted" seeds of the invasives (personal communication [63]).

Winter creeper may also be dispersed by water. A review by Remaley [52] states that it "escapes from neglected gardens and is carried by water to undisturbed forest and riparian areas".

Seed banking: No information is available regarding occurrence or longevity of winter creeper seed in the seed bank.

Germination: As of 2009, no information was available regarding germination of winter creeper in the field; however, a review by Dirr [17] suggests that winter creeper seeds have dormant embryos and recommends moist stratification at cold temperatures for propagation.

Seedling establishment: No information is available on requirements for winter creeper seedling establishment, but it is capable of establishing on disturbed, relatively inhospitable sites (see photo below).

Winter creeper plant growing from crack in pavement, at least 0.5 mile (km) from the nearest established, fruiting plants. Photo courtesy of David Taylor.

Plant growth: A review by Dirr [17] suggests that winter creeper has a "fast" growth rate. A nursery study in northwestern Arkansas using the cultivar 'Coloratus' reported that winter creeper covered almost 75% of its plots with dense foliage within 1 year when grown in beds prepared with mushroom compost and watered from June to September (during establishment) [58]. Winter creeper growth may be affected by a number of factors, including degree of shading (see Shade tolerance) and damage caused by vertebrates, insects, or water stress.

Winter creeper cultivar 'Coloratus' plants damaged by rabbits in fall and winter showed "considerable" regrowth of stems and leaves from March through May, nearly tripling previous growth percentages [58].

Insect damage and water stress can both influence winter creeper growth. Field experiments using the winter creeper cultivar 'Coloratus' suggest that euonymus scales, primarily the males feeding on the leaves, damage the leaf tissue so that the leaves have a higher than normal diffusive resistance and a lower transpiration rate, which eventually leads to increased leaf abscission and impaired growth of root tissue, especially when compounded by water stress [10]. The euonymus scale is native to eastern Asia and is associated with Euonymus spp. throughout most of their native and cultivated range (review by [10]). A greenhouse and field study found that both scale-infested and water-stressed winter creeper plants abscised leaves whereas uninfested, unstressed plants did not; and there was a synergistic effect on leaf abscission from the 2 stresses combined [10]. Winter creeper may abscise a few leaves throughout the year, but most abscission occurs in early spring (unpublished data cited by [10]). Greenhouse experiments using the winter creeper cultivar 'Emerald and Gold' found that leaves began to abscise from water-stressed plants 61 days after infestation and 2 days after the soil water potential reached -1.7 MPa. Feeding by 2 generations of scales on non-water-stressed plants did not reduce total stem growth or significantly reduce intact leaf tissue, but infested plants had lower mean root weight than controls (P=0.05). Water-stressed plants—both infested and uninfested— were shorter, had lower mean root weight, and lower mean intact leaf weight than unstressed plants. Scale infestation significantly decreased the amount of leaf tissue remaining on water-stressed plants (P=0.05). Plants subjected to both water stress and scale infestation abscise more leaves than those exposed to either stress alone, apparently because scale feeding damage causes a heightened sensitivity to other stresses [10].

Vegetative regeneration: Winter creeper spreads vegetatively by producing lateral shoots along the main branches and establishing new, independent plants that emerge from rootlets occurring along procumbent stems at short intervals (reviews by [1,12,52]). When cut, winter creeper sprouts from roots (review by [52]), root crowns, and/or cut stems (review by [17], personal communication [63]). In a nursery study, 'Coloratus' plants damaged by rabbits in fall had considerable regrowth of lateral stems and additional leaves from existing nodes the following spring [58].
	Stem with distinctive buds in May
	Photo by James H. Miller, USDA Forest Service, Bugwood.org

SITE CHARACTERISTICS:
Much of the information regarding site tolerances of winter creeper comes from reviews [1,12,17,30,52,54,62] in which the source of the original information is not given or not clear, and it appears that they mostly cite one another. Very little primary information from field observations was found in the available literature as of 2009. No information was found describing invasive populations: on sites where winter creeper occurred it was typically described as occasional or rare. Thus the following description does not necessarily describe sites where winter creeper is most likely to be invasive.

Disturbance: As a popular ornamental plant, winter creeper is usually associated with human habitation and disturbance. Winter creeper was scarce and occurred only in disturbed areas including park facilities, clearings, and old homesteads at Fall Creek Falls State Park in Tennessee [19]. It occurred in an urban woodland surveyed in 1987 at the Wave Hill Natural Area in Bronx, New York [77], and in disturbed woodlots in Indianapolis that had evidence of extensive human impact and supported several other nonnative and invasive plant species [53]. One of two collections of winter creeper in Michigan was from a gravel pit on dumped roadside debris in Benzie County, in 1982 [73]. From home sites where it was planted, winter creeper sometimes escapes cultivation and establishes, persists, and spreads in surrounding forests, woodlands [1,29,30], riparian communities [1,26,39], and other natural areas (see Habitat Types and Plant Communities). In central Kentucky, winter creeper is most abundant in older neighborhoods and along country roads, where it frequently covers the trunk and lower third of the crown of old roadside trees (personal communication [63]).

Landforms and climate: As of 2009, no information describing landform preferences or climate tolerances was found in the available literature. According to Schwegman [54] winter creeper has spread into forests and rocky bluffs in the eastern and central parts of the United States from Chicago southward, although it also occurs in Michigan [73]. Detrended correspondence analysis suggests an association of winter creeper with floodplains in the eastern United States [39]. Winter creeper is listed as occurring in coastal plain habitats on hydric and mesic sites in Virginia [72]. In a field study of old-growth forests in central Indiana, winter creeper occurred on 2 of 14 edges surveyed and was somewhat more common on warm (south- or west-facing) edges than on cool (north or east-facing) edges [7]. Winter creeper is occasional in deciduous forest and edge habitat in Rock Creek Park in Washington, DC, where the climate is continental, with warm, humid summers and mild to cold winters. The lowest average monthly temperature is 43.5 °F (6.4 °C) in January, and the highest average monthly temperature is 88.2 °F (31.2 °C) in July [20]. Dirr [17] indicates that winter creeper can grow in USDA Hardiness Zone 4, where the average minimum temperature reaches -30 to -20 °F (-34 to -29 °C), but it is not "happy" there unless provided snow cover or winter shade. It better fits USDA Hardiness Zone 5 (average annual minimum teperature of -20 to -10 °F (-29 to -23 °C)) to Zone 8 or 9 (average annual minimum teperature of 20 to 30 °F (-7 to -1 °C)) [17].

No information on winter creeper's elevational range in North America was found in the available literature as of 2009. In its native China, winter creeper occurs from near sea level to 11,155 feet (3,400 m) [76].

Soils: According to reviews, winter creeper is a popular landscape plant due to its rapid growth [1,17] and its ability to tolerate a variety of environmental conditions including heavy shade [1,12,17,30,52], poor soils, and variable pH [1,12,17,52,62]; it apparently does not do well in extremely wet conditions [12,17,30,52]. At Stones River National Battlefield, winter creeper occurs on flat to gently sloping, rocky upland woods on soils derived from limestones or other basic substrates [49]. In Rock Creek Park in Washington, DC, winter creeper occurs on low-fertility, fine-textured soils with pH ranging from 3.6 to 5.5 [20]. Winter creeper occurred on sandy beach berms on the Potomac River lowland that were "occasionally overwhelmed by high tide" [59].

SUCCESSIONAL STATUS:
As of this writing (2009), very little information was available regarding successional relationships of winter creeper. Some authors suggest that it can establish in relatively undisturbed habitats (e.g., [12,30]), and others suggest that populations of winter creeper may establish in forest openings caused by windthrow, insect defoliation, or fire [1,30,52,62]. Records of field observations to support these suggestions were lacking in the available literature. A field study of old-growth forests in central Indiana, which were mostly small woodlots surrounded by agricultural fields, found that winter creeper was at least as frequent in the forest interior as on the forest edge [7].

Observations by Hutchison [29,30] in Illinois suggest that invasive populations of winter creeper may alter successional trajectories because it spreads rapidly and replaces spring ephemerals. In mesic and dry-mesic woods at Fern Rocks Nature Preserve, winter creeper covered the ground and eliminated native groundcover species in many places [29]. Observations by managers in Kentucky indicate that invasive, groundcover populations of winter creeper can establish monocultures in which native species are excluded (personal communication [38]).

Shade tolerance: Several reviews suggest that winter creeper tolerates heavy shade [1,12,17,30,52], and a few of these also suggest that it also tolerates full sun [12,17,30,52]; empirical evidence of winter creeper's shade tolerance is limited and somewhat contradictory. Shade tolerance may vary among cultivars. In a nursery experiment, the cultivar 'Variegata' was grown indoors in containers for 5 months under 1 of 3 conditions: 1) full sun, 2) 47% shade, 3) 64% shade. Growth indices (height + width + width/3, in cm) were significantly different (P≤0.05) among treatments, with growth in full sun the lowest and in 47% shade the highest. Indices were 21.0, 25.0, and 22.9, respectively [34]. A nursery study in northwestern Arkansas using the cultivar 'Coloratus' reported that after fertilizer treatments and 6 months of growth, winter creeper canopy cover was similar and total shoot dry weight was somewhat higher in full sun than in 60% shade. After an additional fertilizer treatment and 6 months of additional growth, shoot and whole plant dry weights for winter creeper were greater under full sun than 60% shade. Statistical comparisons were not made due to lack of replication [58].

FIRE EFFECTS AND MANAGEMENT

• FIRE EFFECTS
• FUELS AND FIRE REGIMES
• FIRE MANAGEMENT CONSIDERATIONS

FIRE EFFECTS:
Immediate fire effect on plant: As of this writing (2009) no information was available in the published literature regarding the immediate effects of fire on winter creeper. Observations by managers indicate that winter creeper does not burn easily and is not likely to be killed by fire of any severity (personal communications [38,63]). When it does burn, winter creeper is only top-killed and sprouts from roots after burning (see Fire adaptations and plant response to fire). Even holding a propane torch in one place for long periods did not kill winter creeper roots; plants were only top-killed and later sprouted (personal communication [38]).

No information was available regarding fire or heat effects on winter creeper seed.

FIRE REGIMES :
Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".

Postfire regeneration strategy [60]:
Small shrub, adventitious buds and/or a sprouting root crown
Initial off-site colonizer (off site, initial community)
Secondary colonizer (on- or off-site seed sources)

Fire adaptations and plant response to fire: As of this writing (2009), no information was available in the published literature regarding winter creeper's fire adaptations or response to fire. Several sources suggest that winter creeper sprouts from roots and root crowns when aboveground vegetation is physically removed (personal communications [38,63], reviews by [1,30,52,54]). Lempke (personal communication [38]) notes that winter creeper is difficult to burn because its leaves have a thick cuticle. When it does burn, observations indicate that winter creeper likely persists by sprouting from the roots and root crown (personal communications [38,63]), even after repeated burning treatments (personal communication [38]). Winter creeper sprouted within about 45 days after plots with 100% winter creeper cover were burned with a propane torch in late March 2003. Plots were burned again when winter creeper reached 30% to 50% cover, and were repeatedly burned throughout the growing season (March through October) for a total of 7 treatments. The following year these plots were burned 5 times during the growing season. These treatments were discontinued, and in 2009, winter creeper covered about 96% of the soil surface, with grasses and sedges composing 2% cover and woody seedlings composing 2% cover (personal communication [38]).

Winter creeper may establish from seeds dispersed onto burns by animals after fire (see Seed dispersal).

FUELS AND FIRE REGIMES:
Fuels: Winter creeper leaves have a thick cuticle, so it is difficult to get the moisture content low enough to burn. Using a 500,000 BTU propane torch it took approximately 35 to 40 minutes to burn 100 square feet of winter creeper at 100% cover. Winter creeper can carry fire in areas where bur oak (Quercus macrocarpa) leaves have accumulated on top of the winter creeper. Patches of winter creeper where leaves have been scorched with a propane torch and allowed to desiccate in warm, dry weather for 3 days may also carry fire (personal communication [38]).

Fire regimes: As of 2009, no information was available regarding fire regimes where winter creeper is native. In North America, winter creeper typically occurs in forests where presettlement fire regimes probably varied. For example, it occurs in oak forests that likely experienced relatively frequent, low-severity fires; and it occurs in mixed mesophytic and northern hardwood forests that probably burned less frequently but with greater severity (reviews by [15,74]). Once established, winter creeper is likely to survive and persist under any of these fire regimes (see Fire adaptations and plant response to fire). See the Fire Regime Table for summaries of fire regime characteristics for vegetation communities in which winter creeper may occur.

Winter creeper may alter fuel properties in invaded areas; however, no data are available on this topic. In areas where winter creeper replaces plants with similar fuel properties, it may alter overall fuel biomass, which has the potential to influence fire intensity. In invaded areas where winter creeper introduces novel fuel characteristics to the invaded system, it may have the potential to alter both fire intensity and fire frequency (sensu [13]). Several reviews (e.g., [5,6,14]) discuss effects of nonnative species invasions on fire regimes.

FIRE MANAGEMENT CONSIDERATIONS:
Preventing postfire establishment and spread: If fire occurs in an area where winter creeper is already established, it is likely to survive and sprout after fire. If fire occurs in an area where winter creeper does not occur on site, but flowering populations are known to occur in the vicinity, the site should be monitored for winter creeper establishment, because seeds are readily spread by birds and other animals (see Seed dispersal). Winter creeper seedlings should be removed immediately upon detection.

During fire suppression and postfire management activities in areas where winter creeper occurs, preventing its establishment and further spread may be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of winter creeper plant material or seed into burned areas. General recommendations for preventing establishment and spread of invasive plants in burn areas include:

• Incorporate cost of weed prevention and management into fire rehabilitation plans
• Acquire restoration funding
• Include weed prevention education in fire training
• Minimize soil disturbance and vegetation removal during fire suppression and rehabilitation activities
• Minimize the use of retardants containing nitrogen and phosphorus
• Avoid areas dominated by high priority invasive plants when locating firelines, monitoring camps, staging areas, and helibases
• Clean equipment and vehicles prior to entering burned areas
• Regulate or prevent human and livestock entry into burned areas until desirable site vegetation has recovered sufficiently to resist invasion by undesirable vegetation
• Monitor burned areas and areas of significant disturbance or traffic from management activity
• Detect weeds early and eradicate before vegetative spread and/or seed dispersal
• Eradicate small patches and contain or control large infestations within or adjacent to the burned area
• Reestablish desirable vegetation on bare ground as soon as possible
• Avoid use of fertilizers in postfire rehabilitation and restoration
• Use only certified weed-free seed mixes when revegetation is necessary

For more detailed information on these topics see the following publications: [4,23,68].

Use of prescribed fire as a control agent: In areas where winter creeper has become a major component of the ground cover, prescribed fire is not likely to carry in the dense winter creeper fuels, and is unlikely to control winter creeper unless used in combination with other treatments (personal communications [38,63]). See Integrated management for details of a management approach that includes burning of winter creeper using a propane torch.

In some forest ecosystems in which winter creeper occurs, fire is either unlikely to burn (personal communication [9]) or is not desirable (review by [29]) due to potential negative impacts on native species.

MANAGEMENT CONSIDERATIONS

• IMPORTANCE TO WILDLIFE AND LIVESTOCK
• OTHER USES
• IMPACTS AND CONTROL

IMPORTANCE TO WILDLIFE AND LIVESTOCK:
Winter creeper was the most heavily browsed of more than 50 ornamental plant species studied during the winters of 1982 to 1984 at the Greenwich Landscaping Company in Connecticut. An average of 97.3% of winter creeper shoots were browsed, substantially more than the congeneric, deciduous shrub winged burning bush (E. alatus) (10% browsed), another nonnative invasive plant [11]. 'Coloratus' plants in a nursery in northwestern Arkansas were damaged by rabbits in fall and winter, presumably because the rabbits were eating it [58].

Palatability/nutritional value: No information is available on this topic.

Cover value: No information is available on this topic.

IMPACTS AND CONTROL:
Impacts: As of this writing (2009), no studies were found in the available literature on the impacts of winter creeper invasion; however, several reviews [12,29,35,52,54,62,64,67] and personal communications [9,38,63] indicate that winter creeper is persistent,competitive, and difficult to control in some areas. A review by Remaley [52] suggests that the traits that make it a desirable ornamental plant, such as rapid growth, evergreen nature, and tolerance of variable site conditions, also make it a threat to natural areas. Reviews suggest that winter creeper outcompetes and displaces native groundlayer plants (e.g., [12,52,62]) and may form single-species stands (review by [54]). Decreased native plant diversity may negatively impact native fauna (e.g., butterflies) [54]. Based on observations in Illinois, Hutchison [29] states that winter creeper is a serious potential threat because it spreads rapidly and replaces spring ephemerals. In mesic and dry-mesic woods at Fern Rocks Nature Preserve, winter creeper covered the ground and eliminated native groundcover species in many places [29]. Reviews suggest that winter creeper may overtop and block sunlight to trees [12,52], possibly smothering and killing them [54], especially smaller trees (up to about 20 feet (6 m) tall) (personal communication [63]).

Winter creeper liana in an ice-felled black cherry (Prunus serotina), approximately 40 feet (12 m) from the root collar. Photos, courtesy of David Taylor, taken 6 March 2009.

Rankings by the USDA, Forest Service [66,67], local exotic pest plant councils [21,35,45,57,64], and the Virginia Department of Conservation and Recreation [72] suggest that as of 2009, winter creeper may be most invasive and have the greatest impact in the Southern Region, especially in Kentucky, Tennessee, and Missouri:

Control: Probably the most effective way to control winter creeper is to prevent its establishment by minimizing its use as a landscape plant and preventing further seed dispersal (see Prevention). Once established, control of winter creeper requires complete removal of plants and roots, because it can spread vegetatively (see Vegetative regeneration). According to Hutchison [30], the most effective management of winter creeper is to totally eradicate it from natural areas and the surrounding vicinity by pulling and removing individuals as soon as possible after recognition.

Fire: For information on the use of prescribed fire to control this species see Fire Management Considerations.

Prevention: It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities [41,55] and by conducting monitoring several times each year [31]. Managing to maintain the integrity of the native plant community and to mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [28].

Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [68]. See the Guide to noxious weed prevention practices for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

The simplest way to prevent winter creeper establishment is to not plant it. Winter creeper is commonly sold as a groundcover for landscaping [12]. Native creeping or climbing vines that may make good alternatives to winter creeper in the eastern United States include trumpet creeper (Campsis radicans), Dutchman's pipe (Aristolochia macrophylla), crossvine (Bignonia capreolata), trumpet honeysuckle (Lonicera sempervirens), American bittersweet (Celastrus scandens), and American wisteria (Wisteria frutescens) [52,62]. If bittersweet and wisteria are used, make sure they are native species, as nonnative species in these genera (C. orbiculatus, W. floribunda, and W. sinensis) are also invasive.

Prevention of fruiting is critical to prevent further spread of winter creeper once it is established. This is accomplished by cutting climbing stems to prevent flowering and fruiting (see Flowering and seed production), and repeating cutting to keep stems from climbing again (personal communication [63]).

Cultural control: According to Hutchison [29], no native species are known that can compete with winter creeper in Illinois. However, planting competitive, desirable native species may help suppress winter creeper as part of an integrated management plan (personal communication [38]).

Physical or mechanical control: Hand-pulling or grubbing using a pulaski or similar digging tool may control small populations of winter creeper (reviews by [1,52]). In order to be effective, the entire plant, including the roots, stem fragments, and fruits, must be bagged and removed from the site to prevent reestablishment. Any portion of the remaining root system may sprout (reviews by [1,30,52,54]). Young plants with small root systems are likely easiest to control in this manner. Hand-pulling is easiest when soils are moist (reviews by [1,52]). Hand-pulling may be impractical for large infestations (review by [29]).

Cutting is not recommended as a control method except to prevent fruiting (personal communication [63], reviews by [43,54]) or in combination with herbicide application (see Chemical control). Cutting alone may lead to sprouting from roots, root crowns, and cut stems (personal communications [38,63], review by [52]). Mowing is similarly ineffective without chemical treatment and not practical in natural areas (review by [29]).

In an area of Kentucky where winter creeper grew in monoculture (no native plants were visible), it was effectively suppressed when light was excluded by covering the population with 6 mil black plastic for an entire growing season (personal communication [38]); however, winter creeper may require 2 years of covering to die (personal communication [9]).

Biological control: Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [71,75] and the Weed control methods handbook [65] for background information and important considerations for developing and implementing biological control programs.

As of this writing (2009), no effective biological controls were known for winter creeper. However, winter creeper is one of the top 10 invasive plants of Asian origin in the United States that is being studied for future biological control opportunities, and scientists are looking for host-specific natural enemies in China [16]. Dirr [17] lists several diseases and insects that impact winter creeper in North America. It is especially susceptible to damage and mortality from the Asian euonymus scale (Unaspis euonymi), which is not native to but does occur in North America [70]. The euonymus scale has been lethal to winter creeper on many plantings, especially those containing the cultivars 'Vegetus', 'Coloratus', and Euonymus tree species such as European spindletree (E. europaeus), winterberry euonymus (E. bungeanus), and Hamilton's spindletree (E. hamiltonianus subsp. sieboldianus) (review by [17]). This same scale is also showing up on native Euonymus species, burningbush (E. atropurpurea) and bursting-heart (E. americanus), and it is causing mortality in populations of Canby's mountain-lover (Paxistima canbyi), a rare subshrub, in Kentucky (personal communication [63]). At least 5 organisms (2 insect predators and 3 aphelinid parasitoids) have been collected in Asia and released in southern New England as biological control agents against the euonymus scale. Releases were made in Massachusetts, Connecticut, and Rhode Island on winter creeper and European spindletree plants infested with medium to large populations of euonymus scale in urban and suburban locations from 1991 to 1995 [70].

Intense seasonal browsing with domestic goats and/or sheep is being investigated as a potential control for winter creeper in Kentucky. This approach shows some promise because winter creeper is reportedly a frequent favorite for most livestock under the right conditions, and it is much browsed by white-tailed deer in the winter (personal communication [9]).

Chemical control: On winter creeper populations that are too large to control by hand-pulling or digging, foliar or cut-stem applications of herbicides may be effective (reviews by [1,12,30,52,54]). Cut stem application of herbicides is effective in areas where lianas are well established on or around nontarget plants or where they have grown into tree canopies or other vertical surfaces. Subsequent foliar application of herbicides will likely be required for adequate control [1,52]. Foliar applications of herbicide may be used to control large populations of winter creeper. It may be necessary to precede foliar sprays with cut stem treatments to reduce the risk of damage to nontarget plants [1,52]. Whichever method is used, multiple herbicide treatments are needed to control winter creeper (personal communications [38,63]) because it sprouts following top-kill.

Recommended timing of herbicide treatment for winter creeper is late fall, when most native vegetation is dormant, or in spring prior to emergence of spring ephemerals (reviews by [12,30]). Herbicide use is not recommended during the growing season, when native species are likely to be impacted. Care should be taken to avoid contacting nontarget species with herbicide (review by [30]).

Herbicides may be effective in gaining initial control of a new invasion or a severe infestation, but they are rarely a complete or long-term solution to weed management [8]. See the Weed control methods handbook [65] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals. See these sources: [1,43,52] for details on specific chemicals, timing, rates, and methods used for controlling winter creeper.

Integrated management: Intensive management of winter creeper monocultures, integrating burning with a propane torch and/or spot spraying with glyphosate followed by planting of desirable species, may effectively suppress winter creeper and promote desirable plant communities. Monocultures in Kentucky were sprayed with glyphosate in spring, when there were about 6 newly-formed leaves without a thick cuticle. Leaves turned red and dropped off in the fall. Any new winter creeper sprouts that emerged the following spring were spot sprayed with glyphosate, and where the native seed bank was slow to respond, wild rye (Elymus villosus and E. macgregori) was seeded. Areas with dense wild rye stands had no rebound of winter creeper populations (personal communication [38]).

An intensively managed swale that was once 100% winter creeper. Treatments were: burning with propane torch, followed by spot spraying of glyphosate and hand pulling of sprouts the 1st year; and planting swamp milkweed (Asclepias incarnata), wild rye and fowl manna grass (Glyceria striata) plugs the 2nd year. Photo taken in year 3 (personal communication [38]). Photo courtesy of Jim Lempke, University of Kentucky Arboretum

APPENDIX: FIRE REGIME TABLE

SPECIES: Euonymus fortunei

Euonymus fortunei: REFERENCES

1. Bean, Ellen; McClellan, Linnea, tech. eds. 1996. Tennessee exotic plant management manual, [Online]. Southeast Exotic Pest Plant Council (Producer). Available: http://www.tneppc.org/Manual/manual.pdf [2009, March 23]. [46442]

2. Blakelock, R. A. 1951. A synopsis of the genus Euonymus L. Kew Bulletin. 6(2): 210-290. [71719]

3. Braun, E. Lucy. 1989. The woody plants of Ohio. Columbus, OH: Ohio State University Press. 362 p. [12914]

4. Brooks, Matthew L. 2008. Effects of fire suppression and postfire management activities on plant invasions. In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L., eds. Wildland fire in ecosystems: Fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 269-280. [70909]

5. Brooks, Matthew L. 2008. Plant invasions and fire regimes. In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L., eds. Wildland fire in ecosystems: fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 33-45. [70467]

6. Brooks, Matthew L.; D'Antonio, Carla M.; Richardson, David M.; Grace, James B.; Keeley, Jon E.; DiTomaso, Joseph M.; Hobbs, Richard J.; Pellant, Mike; Pyke, David. 2004. Effects of invasive alien plants on fire regimes. BioScience. 54(7): 677-688. [50224]

7. Brothers, Timothy S.; Spingarn, Arthur. 1992. Forest fragmentation and alien plant invasion of central Indiana old-growth forests. Conservation Biology. 6(1): 91-100. [19616]

8. Bussan, Alvin J.; Dyer, William E. 1999. Herbicides and rangeland. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 116-132. [35716]

9. Campbell, Julian. 2009. [Email to Kris Zouhar]. June 4. Regarding wintercreeper euonymus. Lexington, KY: Bluegrass Woodland Restoration Center. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab, Missoula, MT; FEIS files. [74660]

10. Cockfield, S. D.; Potter, D. A. 1986. Interaction of Euonymus scale (Homoptera: Diaspididae) feeding damage and severe water stress on leaf abscission and growth of Euonymus fortunei. Oecologia. 71(1): 41-46. [71712]

11. Conover, M. R.; Kania, G. S. 1988. Browsing preference of white-tailed deer for different ornamental species. Wildlife Society Bulletin. 16: 175-179. [8933]

12. Czarapata, Elizabeth J. 2005. Invasive plants of the Upper Midwest: An illustrated guide to their identification and control. Madison, WI: The University of Wisconsin Press. 215 p. [71442]

13. D'Antonio, Carla M. 2000. Fire, plant invasions, and global changes. In: Mooney, Harold A.; Hobbs, Richard J., eds. Invasive species in a changing world. Washington, DC: Island Press: 65-93. [37679]

14. D'Antonio, Carla M.; Vitousek, Peter M. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecology and Systematics. 23: 63-87. [20148]

15. Dibble, Alison C.; Zouhar, Kristin; Smith, Jane Kapler. 2008. Fire and nonnative invasive plants in the Northeast bioregion. In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L., eds. Wildland fire in ecosystems: fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 61-90. [70902]

16. Ding, Jianqing; Reardon, Richard; Wu, Yun; Zheng, Hao; Fu, Weidong. 2006. Biological control of invasive plants through collaboration between China and the United States of America: a perspective. Biological Invasions. 8(7): 1439-1450. [71691]

17. Dirr, Michael A. 1998. Manual of woody landscape plants: Their identification, ornamental characteristics, culture, propagation and uses. 5th ed. Champaign, IL: Stipes Publishing. 1187 p. [74836]

18. Fernald, Merritt Lyndon. 1950. Gray's manual of botany. [Corrections supplied by R. C. Rollins]. Portland, OR: Dioscorides Press. 1632 p. (Dudley, Theodore R., gen. ed.; Biosystematics, Floristic & Phylogeny Series; vol. 2). [14935]

19. Fleming, Chris A.; Wofford, B. E. 2004. The vascular flora of Fall Creek Falls State Park, Van Buren and Bledsoe counties, Tennessee. Castanea. 69(3): 164-184. [71700]

20. Fleming, Peggy; Kanal, Raclare. 1995. Annotated list of vascular plants of Rock Creek Park, National Park Service, Washington, DC. Castanea. 60(4): 283-316. [71991]

21. Georgia Exotic Pest Plant Council. 2006. List of non-native invasive plants in Georgia, [Online]. Southeast Exotic Pest Plant Council (Producer). Available: http://www.gaeppc.org/list.cfm [2009, January 5]. [72787]

22. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York: New York Botanical Garden. 910 p. [20329]

23. Goodwin, Kim; Sheley, Roger; Clark, Janet. 2002. Integrated noxious weed management after wildfires. EB-160. Bozeman, MT: Montana State University, Extension Service. 46 p. Available online: http://www.montana.edu/wwwpb/pubs/eb160.html [2003, October 1]. [45303]

24. Grese, R. 1992. The landscape architect and problem exotic plants. In: Burley, J. B., ed. Proceedings, American Society of Landscape Architects' open committee on reclamation: reclamation diversity; 1991 October 29; San Diego, CA. [Washington, DC]: [American Society of Landscape Architects]: 7-15. On file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. [20122]

25. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2008. Interagency fire regime condition class guidebook. Version 1.3, [Online]. In: Interagency fire regime condition class website. U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; The Nature Conservancy; Systems for Environmental Management (Producer). 119 p. Available: http://frames.nbii.gov/frcc/documents/FRCC_Guidebook_2008.07.10.pdf [2008, September 03]. [70966]

26. Harrelson, Sarah M.; Cantino, Philip D. 2006. The terrestrial vascular flora of Strounds Run State Park, Athens County, Ohio. Rhodora. 108(934): 142-183. [72485]

27. Henry, R. D.; Scott, A. R. 1981. Time of introduction of the alien component of the spontaneous Illinois vascular flora. The American Midland Naturalist. 106(2): 318-324. [71750]

28. Hobbs, Richard J.; Humphries, Stella E. 1995. An integrated approach to the ecology and management of plant invasions. Conservation Biology. 9(4): 761-770. [44463]

29. Hutchison, Max. 1990. Wintercreeper or climbing euonymous (Euonymous fortunei), [Online]. In: Vegetation management guideline--Vol. 1, No. 27. Urbana-Champaign, IL: Illinois Natural History Survey; University of Illinois, Institute of Natural Resource Sustainability (Producers). Available: http://www.inhs.uiuc.edu/chf/outreach/VMG/wintercreu.html [2009, June 12]. [74692]

30. Hutchison, Max. 1992. Vegetation management guideline: wintercreeper or climbing euonymus (Euonymus fortunei). Natural Areas Journal. 12(4): 220-221. [20072]

31. Johnson, Douglas E. 1999. Surveying, mapping, and monitoring noxious weeds on rangelands. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 19-36. [35707]

32. Johnson, Kristine. 2009. [Email to Kris Zouhar]. June 1. Regarding wintercreeper. Gatlinburg, TN: Great Smoky Mountains National Park. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab, Missoula, MT; FEIS files. [74688]

33. Kartesz, John T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. 1st ed. In: Kartesz, John T.; Meacham, Christopher A. Synthesis of the North American flora (Windows Version 1.0), [CD-ROM]. Chapel Hill, NC: North Carolina Botanical Garden (Producer). In cooperation with: The Nature Conservancy; U.S. Department of Agriculture, Natural Resources Conservation Service; U.S. Department of the Interior, Fish and Wildlife Service. [36715]

34. Keever, G. J.; Cobb, G. S.; Stephenson, J. C. 1988. Interior performance of temperate zone landscape plants. Journal of Environmental Horticulture. 6(3): 84-87. [71713]

35. Kentucky Exotic Pest Plant Council. 2008. Invasive exotic plant list, [Online]. Southeast Exotic Pest Plant Council (Producer). Available: http://www.se-eppc.org/ky/list.htm [2009, January 5]. [72785]

36. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior (Producers). 72 p. Available: http://www.landfire.gov/downloadfile.php?file=RA_Modeling_Manual_v2_1.pdf [2007, May 24]. [66741]

37. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models, [Online]. In: LANDFIRE. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; The Nature Conservancy (Producers). Available: http://www.landfire.gov/models_EW.php [2008, April 18] [66533]

38. Lempke, Jim. 2009. [Email to Kris Zouhar]. June 4. Regarding wintercreeper euonymus. Lexington, KY: University of Kentucky Arboretum. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT; FEIS files. [74687]

39. Luken, James O. 2003. Invasions of forests in the eastern United States. In: Gilliam, Frank S.; Roberts, Mark R., eds. The herbaceous layer in forests of eastern North America. New York: Oxford University Press, Inc: 283-400. [71484]

40. Mack, Richard N. 2002. Natural barriers to plant naturalizations and invasions in the Sonoran Desert. In: Tellman, Barbara, ed. Invasive exotic species in the Sonoran region. Arizona-Sonora Desert Museum Studies in Natural History. Tucson, AZ: The University of Arizona Press; The Arizona-Sonora Desert Museum: 63-76. [48650]

41. Mack, Richard N.; Simberloff, Daniel; Lonsdale, W. Mark; Evans, Harry; Clout, Michael; Bazzaz, Fakhri A. 2000. Biotic invasions: causes, epidemiology, global consequences, and control. Ecological Applications. 10(3): 689-710. [48324]

42. Magee, Dennis W.; Ahles, Harry E. 2007. Flora of the Northeast: A manual of the vascular flora of New England and adjacent New York. 2nd ed. Amherst, MA: University of Massachusetts Press. 1214 p. [74293]

43. Miller, James H. 2003. Nonnative invasive plants of southern forests: A field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p. Available online: http://www.srs.fs.usda.gov/pubs/gtr/gtr_srs062/ [2004, December 10]. [50788]

44. Miller, James H.; Chambliss, Erwin B.; Oswalt, Christopher M. 2008. Estimated acres covered by the 33 nonnative invasive plants species in a state and Southern Region, [Online]. In: Maps of occupation and estimates of acres covered by nonnative invasive plants in southern forests using SRS FIA data posted on March 15, 2008. Athens, GA: University of Georgia, Bugwood Network; Washington, DC: U.S. Department of Agriculture, Forest Service; Animal and Plant Inspection Service, Plant Protection and Quarantine (Producers). Available: http://www.invasive.org/fiamaps/summary.pdf [2009, January 15]. [72772]

45. Missouri Botanical Garden. 2002. Missouri exotic pest plants: A list of non-native plants that threaten Missouri's native biodiversity, [Online]. In: MO projects--North America. St. Louis, MO: Missouri Botanical Garden (Producer). Available: http://www.mobot.org/mobot/research/mepp/alphalist.shtml [2009, April 6]. [73559]

46. Mohlenbrock, Robert H. 1986. [Revised edition]. Guide to the vascular flora of Illinois. Carbondale, IL: Southern Illinois University Press. 507 p. [17383]

47. Mohlenbrock, Robert H.; Ladd, Douglas M.. 1978. Distribution of Illinois vascular plants. Carbondale, IL: Southern Illinois University Press at Carbondale and Edwardsville. 282 p. [17554]

48. Muhlenbach, Victor. 1979. Contributions to the synanthropic (adventive) flora of the railroads in St. Louis, Missouri, USA. Annals of the Missouri Botanical Garden. 66(1): 1-108. [71736]

49. Nordman, Carl. 2004. Vascular plant community classification for Stones River National Battlefield. NatureServe Technical Report. [Prepared for the National Park Service: Cooperative Agreement H 5028 01 0435]. Durham, NC: NatureServe. 157 p. Available online: http://www.nps.gov/stri/naturescience/upload/STRI%20Final%20Report4.pdf [2009, June 12]. [74667]

50. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. [7606]

51. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843]

52. Remaley, Tom. 2005. Fact sheet: Climbing euonymus--Euonymus fortunei (Turcs.) Hand.-Mazz., [Online]. In: Weeds gone wild: Alien plant invaders of natural areas. The Plant Conservation Alliance's Alien Plant Working Group (Producer). Available: http://www.nps.gov/plants/alien/fact/pdf/eufo1.pdf [2009, June 12]. [71707]

53. Salsbury, Carmen M.; Dolan, Rebecca W.; Pentzer, Emily B. 2004. The distribution of fox squirrel (Sciurus niger) leaf nests within forest fragments in central Indiana. The American Midland Naturalist. 151(2): 369-377. [48557]

54. Schwegman, John E. 1996. Euonymus fortunei--wintercreeper. In: Randall, John M.; Marinelli, Janet, eds. Invasive plants: Weeds of the global garden. Handbook #149. Brooklyn, NY: Brooklyn Botanic Garden: 56. [72875]

55. Sheley, Roger; Manoukian, Mark; Marks, Gerald. 1999. Preventing noxious weed invasion. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 69-72. [35711]

56. Shelter, Stanwyn G.; Orli, Sylvia S.; Wells, Elizabeth F.; Beyersdorfer, Marcie. 2006. Checklist of the vascular plants of Plummers Island, Maryland. Bulletin of the Biological Society of Washington. 14(1): 1-57. [72486]

57. South Carolina Exotic Pest Plant Council. 2008. Invasive plant list, [Online]. Southeast Exotic Pest Plant Council (Producer). Available: http://www.se-eppc.org/southcarolina/SCEPPC_LIST_offical_2008.xls [2009, January 5]. [72717]

58. Stafne, R. A.; Einert, A. E.; Klingaman, G. L. 2005. Fertilizer applications on establishment and growth of three groundcover species in sun and shade. Journal of Environmental Horticulture. 23(3): 157-161. [71717]

59. Steury, Brent W; Davis, Charles A. 2003. The vascular flora of Piscataway and Fort Washington National Parks, Prince Georges and Charles Counties, Maryland. Castanea. 68(4): 271-299. [73054]

60. Stickney, Peter F. 1989. Seral origin of species comprising secondary plant succession in Northern Rocky Mountain forests. FEIS workshop: Postfire regeneration. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. 10 p. [20090]

61. Stocker, Randall; Hupp, Karen V. S. 2008. Fire and nonnative invasive plants in the Southeast bioregion. In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L., eds. Wildland fire in ecosystems: fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 91-112. [70903]

62. Swearingen, J.; Reshetiloff, K.; Slattery, B.; Zwicker, S. 2002. Plant invaders of mid-Atlantic natural areas. [Washington, DC]: U.S. Department of the Interior, National Park Service; Fish and Wildlife Service. 82 p. Available online: http://www.invasive.org/eastern/midatlantic/index.html [2005, September 9]. [54192]

63. Taylor, David. 2009. [Email to Kris Zouhar]. June 3. Regarding invasive plants. Winchester, KY: Daniel Boone National Forest. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT; FEIS files. [74698]

64. Tennessee Exotic Pest Plant Council. 2001. Invasive exotic pest plants in Tennessee, [Online]. In: Invasive exotic plants. Fairview, TN: Tennessee Exotic Pest Plant Council (Producer) Available: http://www.tneppc.org/Invasive_Exotic_Plant_List/The_List.htm [2009, June 12]. [74677]

65. Tu, Mandy; Hurd, Callie; Randall, John M., eds. 2001. Weed control methods handbook: tools and techniques for use in natural areas. Davis, CA: The Nature Conservancy. 194 p. [37787]

66. U.S. Department of Agriculture, Forest Service, Eastern Region. 2004. Eastern Region invasive plants ranked by degree of invasiveness, [Online]. In: Noxious weeds and non-native invasive plants. Section 3: Invasive plants. Milwaukee, WI: Eastern Region (Producer). Available: https://www.fs.usda.gov /r9/wildlife/range/weed/Sec3B.htm [2004, February 16]. [46748]

67. U.S. Department of Agriculture, Forest Service, Southern Region. 2001. Regional invasive exotic plant species list, [Online]. In: Regional Forester's list and ranking structure: invasive exotic plant species of management concern. In: Invasive plants of southern states list. Southeast Exotic Pest Plant Council (Producer). Available: http://www.se-eppc.org/fslist.cfm [2003, August 25]. [44944]

68. U.S. Department of Agriculture, Forest Service. 2001. Guide to noxious weed prevention practices. Washington, DC: U.S. Department of Agriculture, Forest Service. 25 p. Available online: https://www.fs.usda.gov /rangelands/ftp/invasives/documents/GuidetoNoxWeedPrevPractices_07052001.pdf [2005, October 25]. [37889]

69. U.S. Department of Agriculture, Natural Resources Conservation Service. 2009. PLANTS Database, [Online]. Available: https://plants.usda.gov /. [34262]

70. Van Driesche, R. G.; Iodine, K.; Rose, M.; Bryan, M. 1998. Release, establishment and spread of Asian natural enemies of Euonymus scale (Homoptera: Diaspididae) in New England. Florida Entomologist. 81(1): 1-9. [71720]

71. Van Driesche, Roy; Lyon, Suzanne; Blossey, Bernd; Hoddle, Mark; Reardon, Richard, tech. coords. 2002. Biological control of invasive plants in the eastern United States. USDA Forest Service Publication FHTET-2002-04. [Washington, DC]: U.S. Department of Agriculture, Forest Service. 413 p. Available online: http://www.invasive.org/eastern/biocontrol/index.html [2005, August 12]. [54194]

72. Virginia Department of Conservation and Recreation, Division of Natural Heritage. 2003. Invasive alien plant species of Virginia, [Online]. In: Natural Heritage Program--Invasive plants list. Richmond, VA: Virginia Department of Conservation and Recreation, Division of Natural Heritage; Virginia Native Plant Society (Producers). Available: http://www.dcr.virginia.gov/natural_heritage/documents/invlist.pdf [2009, March 23]. [44942]

73. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472]

74. Wade, Dale D.; Brock, Brent L.; Brose, Patrick H.; Grace, James B.; Hoch, Greg A.; Patterson, William A., III. 2000. Fire in eastern ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 53-96. [36983]

75. Wilson, Linda M.; McCaffrey, Joseph P. 1999. Biological control of noxious rangeland weeds. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 97-115. [35715]

76. Wu, Z. Y.; Raven, P. H.; Hong, D. Y., eds. 2009. Flora of China, [Online]. Volumes 1-25. Beijing: Science Press; St. Louis, MO: Missouri Botanical Garden Press. In: eFloras. St. Louis, MO: Missouri Botanical Garden; Cambridge, MA: Harvard University Herbaria (Producers). Available: http://www.efloras.org/flora_page.aspx?flora_id=2 and http://flora.huh.harvard.edu/china. [72954]

77. Yost, Susan E.; Antenen, Susan; Harvigsen, Gregg. 1991. The vegetation of the Wave Hill Natural Area, Bronx, New York. Torreya. 118(3): 312-325. [16546]