Fire Effects Information System (FEIS)

FEIS Home Page

INTRODUCTORY

AUTHORSHIP AND CITATION FEIS ABBREVIATION NRCS PLANT CODE COMMON NAMES TAXONOMY SYNONYMS LIFE FORM FEDERAL LEGAL STATUS OTHER STATUS
	© M. Simpson, wordsrmagic2me.com

AUTHORSHIP AND CITATION:
Gucker, Corey L. 2007. Pyrola asarifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.usda.gov/database/feis/plants/forb/pyrasa/all.html [].

Revisions: On 5 July 2017, the common name of this species was changed from: pink wintergreen
to: liverleaf wintergreen in FEIS.

Infrataxa:
Pyrola asarifolia Michx. subsp. asarifolia [17,28,31,34]
Pyrola asarifolia subsp. bracteata (Hook.) Haber [17,28,31,34]

Hybrids: Naturally occurring hybrids of liverleaf wintergreen × largeflowered wintergreen (P. grandiflora) occur in British Columbia and the Yukon Territory [17]. Liverleaf wintergreen × snowline wintergreen (P. minor) hybrid populations occur in Quebec, Ontario, Colorado, Alberta, British Columbia, Yukon, and Alaska [18].

Pyrola asarifolia var. incarnata (DC.) Fern. [1,4,26]=
   Pyrola asarifolia subsp. asarifolia [34]

Pyrola asarifolia var. purpurea (Bunge) Fern. [30,33,42,57,64,89]=
   Pyrola asarifolia subsp. asarifolia [34]

Pyrola bracteata Hook. [46,63,70]=
   Pyrola asarifolia subsp. asarifolia [34]

Pyrola californica Krisa [56]=
   Pyrola asarifolia subsp. asarifolia [34]

Pyrola rotundifolia subsp. asarifolia (Michx.) A&D Löve [93,94]=
   Pyrola asarifolia subsp. asarifolia [34]

Pyrola uliginosa Torr. & Gray ex Torr. [6,7,70,81]=
   Pyrola asarifolia subsp. asarifolia [34]

DISTRIBUTION AND OCCURRENCE

• GENERAL DISTRIBUTION
• HABITAT TYPES AND PLANT COMMUNITIES

Plants Database provides a distributional map of liverleaf wintergreen and its subspecies.

The following vegetation types and communities include liverleaf wintergreen as a dominant or differentiating species:

• narrowleaf cottonwood (Populus angustifolia)-Douglas-fir/liverleaf wintergreen

• Douglas-fir/Rocky Mountain maple (Acer glabrum)/liverleaf wintergreen along Animas River in southwestern Colorado [90]

• black cottonwood (P. balsamifera subsp. trichocarpa)/liverleaf wintergreen on the coast [39]

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

Aboveground description: Liverleaf wintergreen is an evergreen, glabrous, creeping perennial [1,30,57,61]. Nearly leafless flowering stalks are the tallest part of the plant [31]. Basal leaves are simple, alternate, and crowded in a rosette [31,35]. Blades are leathery, shiny, and circular to heart-shaped [33,61]. Leaf petioles are typically as long as the leaf blades [30,61]. Holmgren and others [31] report that leaf blades measure 0.8 to 4 inches (2-10 cm) long by 0.8 to 3 inches (2-8 cm) wide, and that petioles are 0.6 to 3.3 inches (1.5-8.5 cm) long. However, morphology is variable and affected by site conditions [17]. In western habitats leaf blades are generally wider than they are long, and in eastern habitats leaf blades are typically longer than they are wide. Leaves are often leathery in dry habitats and soft in wet habitats. Plants in moss hummocks often have particularly long, flexible petioles [17]. Liverleaf wintergreen, as the name implies, produces liverleaf to red-purple flowers, and flower color is often used in identification. Four to 25 nodding flowers occur in a loose raceme on stems up to 16 inches (40 cm) tall [1,17,31,61]. Flower stalks may have up to 3 scale leaves [13,14]. Liverleaf wintergreen fruits are 5-chambered rounded capsules [1,61]. Capsules measure 4 to 8 mm in diameter, contain numerous seeds, and open from the base [1,14,52].

Belowground description: Liverleaf wintergreen is rhizomatous. Rhizomes are shallow [16,30] and described as scaly, slender, long, branching, and extensive [14,17,61]. In jack pine (Pinus banksiana)-dominated stands in central Alberta, the maximum liverleaf wintergreen rooting depth was 7.1 inches (18 cm) [78].

Subspecies: A key for distinguishing P. a. subsp. asarifolia and P. a. subsp. bracteata is available [17].

Pollination: Because liverleaf wintergreen produces perfect flowers, self pollination is possible, but pollination strategies were not discussed in the available literature (2007).

Breeding system: Liverleaf wintergreen flowers are perfect [26].

Seed production and dispersal: The only studies of liverleaf wintergreen seed production, dispersal, and banking are summarized in seed banking.

Seed banking: Liverleaf wintergreen germinated from soils collected in tufted hairgrass/sedge (Deschampsia caespitosa/Carex spp.) meadows in the Greater Yellowstone ecosystem of Montana and Wyoming but not from soils collected in mixed forests in Oregon's central Cascade Range or from soils collected in quaking aspen (Populus tremuloides) woodlands in northeastern Alberta. Fifty-three liverleaf wintergreen seedlings/m² emerged from seed in soils collected in unburned tufted hairgrass meadows. Almost double this number of seedlings emerged when unburned soil samples were heated to 120 °F (50 °C) for 1 hour. Emergence was about half as much when heated to 210 °F (100 °C) for 1 hour. There was no emergence from soils heated at 300 °F (150 °C) for 1 hour or from soils collected in burned meadows [4]. Additional information on this study is available in Fire Effects.

Liverleaf wintergreen was not collected in seed traps and did not germinate from soil samples collected in mixed forests or gravel bars in Oregon's central Cascade Range. In mixed forest sites, liverleaf wintergreen occurred with an average of 0.1% cover/m²; liverleaf wintergreen was not present on vegetated or unvegetated gravel bars within active third- and fifth-order streams. Soil samples were collected in mid-March, and emergence from rhizome pieces and seeds was monitored under greenhouse conditions [24]. Liverleaf wintergreen did not emerge from vegetative propagules or seed in soil samples collected on burned or unburned quaking aspen stands in northeastern Alberta. Lightly and severely burned sites were sampled. The fire on severely burned sites consumed all aboveground vegetation and oxidized the top 2 to 4 inches (6-10 cm) of the organic soil layer. Light fires partially oxidized the top 0 to 0.8 inch (2 cm) of the organic layer, primarily mosses and litter. Unburned stands were over 120 years old [49].

Germination: The little information on liverleaf wintergreen seed germination comes from the study conducted by [4], which is presented in seed banking.

Seedling establishment/growth: No information is available on this topic.

Vegetative regeneration: Liverleaf wintergreen regenerates vegetatively by rhizomes. Researchers in south-central Alaska's Wrangell-St Elias National Park classified liverleaf wintergreen as a "guerilla" colonizer because daughter ramets typically occurred beyond the perimeter of the aboveground parent plant [10].

In the Vancouver Forest Region of British Columbia, liverleaf wintergreen indicates "dry to moist, nutrient-medium" sites [37]. In seral shrub communities within the western redcedar-western hemlock forest type in northern Idaho, liverleaf wintergreen was most frequent on slopes over 60% and at the study area's northernmost latitudes. Liverleaf wintergreen was significantly associated (P<0.05) with northern slopes, soils with low potassium levels (60-300 lbs/acre), and dense stands with 40% to 80% canopy cover [55].

Climate: Cool moist climates are typical in liverleaf wintergreen habitats. In the McKinley River area of Alaska, liverleaf wintergreen is described in habitats that average 20.3 inches (515 mm) of precipitation/year, most of which comes in the summer. Average January and July temperatures are -2.2 °F (-19 °C) and 52.7 °F (11.5 °C), respectively, with maximum and minimum temperatures of 81 °F (27 °C) and -45 °F (-43 °C) reported [87]. Liverleaf wintergreen in coastal British Columbia experiences boreal, temperate, cool mesothermal climates [38]. Climate is humid, continental in lodgepole pine forests in Alberta's northern McLeod River Basin, where liverleaf wintergreen occurs. Here winters are cold, summers are cool, and freezing temperatures are possible any month. July and January temperatures average 58.8 °F (14.9 °C) and 6.8 °F (-14 °C), respectively, and annual precipitation averages 21.7 inches (550 mm) [9]. Weather records from the Priest River Experimental Station describe the climate for liverleaf wintergreen habitats in north Idaho's Selkirk Mountains. Annual precipitation is high, and nearly 75% falls as snow from October to April. The dormant season is long and cool, and the growing season is short, warm, and dry. The frost-free period averages 88 days [74]. A cool temperate climate prevails at Point Beach State Forests in Two Rivers, Wisconsin, where liverleaf wintergreen occurs. Based on a 24-year record, time between frosts averaged 62 days. An extreme low of -12 °F (-24 °C) occurred in January, and an extreme high of 88 °F (31 °C) was reached in June. Annual precipitation averaged 25 inches (635 mm), and most came in May, July, and November [85].

Elevation: Liverleaf wintergreen occupies higher elevations in the southern than in the northern part of its range.

Soils: Liverleaf wintergreen occurs on a variety of substrate types, but soils are typically moist, acidic, and have thick litter or humus layers. In Manitoba, liverleaf wintergreen grew in "fresh" to very moist, clayey, loamy, silty, and sandy soils [96]. In northwestern Quebec, liverleaf wintergreen occurred only on mesic clay soils when boreal forests on clay and till surface deposits were compared [50].

In white fir-mixed conifer forests in the Sierra Nevada of California, liverleaf wintergreen was common on soils covered with a "heavy carpet of litter" [66]. In forests along the Tanana River of interior Alaska, liverleaf wintergreen occurred in open balsam poplar (Populus balsamifera) woodlands with a forest floor thickness of 2 to 4 inches (5-10 cm) and 225 to 350 g/m² of leaf litter. Liverleaf wintergreen also grew in open black spruce (Picea mariana) forests with a floor thickness of 9.8 to 12 inches (25-30 cm), 30 to 100 g/m² of leaf litter, and a 12- to 20-inch (30-50 cm)-deep organic layer [86]. In the McKinley River Area, liverleaf wintergreen was described in birch-willow shrublands on glacial outwash deposits where humus layers were up to 14 inches (35 cm) thick, and pH was less than 5.7 [87].

Liverleaf wintergreen occupied dry to wet sites within boreal conifer-hardwood forests of the Great Lakes region. Dry and wet soils averaged 161% and 365% dry-weight moisture-retaining capacity, respectively. Soil pH ranged from 4.5 to 4.9 [53]. In coastal British Columbia, liverleaf wintergreen is indicative of moderately dry, fresh, and nitrogen-medium soils. Moderately dry soils experience water deficits more than 1.5 but less than 3.5 months/year. When water needs exceed supply and soil-stored water is used, soils are considered fresh. Nitrogen-medium soils are those with an average of 54 kg of mineralizable nitrogen/ha [38].

Shade tolerance: Liverleaf wintergreen tolerates both sun and shade conditions [38]. The degree of shade tolerated has been described as extreme [45]. Although sun and shade are tolerated, studies suggest that shady habitats may be preferred. Liverleaf wintergreen was significantly associated (P<0.001) with mesic, closed-canopy, mixed-conifer forests with thick litter layers and high soil moisture contents in the southern Sierra Nevada [60]. In northern Idaho, liverleaf wintergreen was significantly associated (P<0.05) with dense seral mixed-shrub stands with 40% to 80% canopy cover [55].

Floodplain/glacier outwash succession: Along floodplain chronosequences, liverleaf wintergreen is often present on early substrates with canopy vegetation and persists in dense climax forests. On the Tanana River floodplain in interior Alaska, liverleaf wintergreen appears approximately 25 to 30 years after silt bars form along the active river channel. This early seral community is characterized by open balsam poplar-dominated stands with a dense thinleaf alder (Alnus incana subsp. tenuifolia) understory. Liverleaf wintergreen remains in the understory in later, conifer-dominated stands [84,88]. Along a glacial outwash plain in Kenai Fjords National Park, Alaska, liverleaf wintergreen cover was greatest in late-seral forests dominated by Sitka spruce and mountain hemlock (Tsuga mertensiana). Liverleaf wintergreen was absent from early seral communities described as barren or with patchy vegetation dominated by balsam poplar and willow [27].

Grazing: While no study indicates that liverleaf wintergreen is consumed by herbivores, the following studies suggest that grazing in liverleaf wintergreen habitats may affect its abundance. Snowshoe hare and moose browsing were evaluated on enclosed and unprotected thinleaf alder-willow stands on the Tanana River floodplain. Liverleaf wintergreen abundance was lower on browsed than protected sites. Sites were protected for 7 years. Browsed plots had lower tree cover, soil moisture, and relative humidity and received more light and higher ground temperatures than unbrowsed plots [80]. In the Peace River region of British Columbia, liverleaf wintergreen cover was slightly greater in grazed quaking aspen stands. Liverleaf wintergreen cover was 1.5% on harvested and grazed plots, 1.2% on unharvested grazed plots, 0.5% on harvested ungrazed plots, and 1% on unharvested ungrazed plots. Harvesting occurred 12 years before vegetation sampling. Cattle grazed plots from early June to early July for 9 years and utilized about 75% of available forage. Grazing had not occurred for 3 years before vegetation sampling [40].

Logging: Results are inconsistent with respect to liverleaf wintergreen in logged stands. Some studies report that liverleaf wintergreen disappears from clearcut sites while others report a tolerance of clearcut conditions.

Liverleaf wintergreen occurred only in young mixed Douglas-fir-lodgepole pine forests in south-central British Columbia. Young stands were clearcut 17 years before the study. Other forests evaluated as part of the study were seed-tree harvested stands with 106- to 149-year-old Douglas-fir trees and unharvested stands with 70- to 133-year-old trees [79]. In the northern McLeod River Basin, liverleaf wintergreen occurred in 6-, 7-, 9-, 10-, and 12-year-old clearcuts and in mature lodgepole pine forests [9].

In northeastern British Columbia, liverleaf wintergreen was much more abundant in unlogged than logged stands in nearly 100-year-old quaking aspen woodlands [20]. In western Oregon and Washington, liverleaf wintergreen was often absent from harvested Douglas-fir forests with 15% or 40% tree retention [21]. Liverleaf wintergreen was eliminated in logged and burned stands in the same area. Before logging, forests were dominated by 120- to over 430-year-old Douglas-fir trees. Understory species presence was evaluated before logging and periodically for up to 28 years after the disturbances [22]. For more on this study, see Fire Effects.

There was liverleaf wintergreen turnover when individual plots were observed in clearcut quaking aspen-lodgepole pine stands; however, overall occurrence was not different in 3- and 20-year old clearcuts. Liverleaf wintergreen occurrence was monitored on 88 plots near Grande Prairie, Alberta. Forests were dominated by 62- to 82-foot (19-25 m)-tall quaking aspen before harvesting. Forests were about 20% lodgepole pine. Three years following harvest, liverleaf wintergreen occurred on 28 of 88 plots. On 5-year-old clearcuts, liverleaf wintergreen disappeared from 8 plots where it was previously detected and appeared on 3 new plots where it was not detected earlier. Liverleaf wintergreen was present on a total of 33 of the 5-year-old clearcut plots. Nine years after harvest, liverleaf wintergreen occurred on 3 new plots and was not detected on 16 plots that it had earlier occupied. Liverleaf wintergreen occurred on a total of 20 of the 9-year-old clearcut plots. On 20-year-old clearcuts, liverleaf wintergreen disappeared from 3 plots, appeared on 20 new plots, and was present on a total of 30 plots. It is possible that there was considerable liverleaf wintergreen mortality and regeneration on this site, but it is also possible that liverleaf wintergreen remained dormant in some years. Sampling techniques may have also affected results [77]. See Fire Effects for additional information on liverleaf wintergreen in the early succession of sites following canopy removal.

Other disturbances: The following studies suggest that liverleaf wintergreen tolerates some level of soil disturbance. These studies, however, suggest that the degree of soil disturbance tolerated and recovery time may be site dependent. Liverleaf wintergreen occurred on grizzly bear digs in alpine tundra in Wrangell-St Elias National Park. Digs were made in the hunt for arctic ground squirrels and involved a deep excavation of sod and mineral soil. Dig area ranged from 10 to 200 feet² (1-20 m²) [10]. Liverleaf wintergreen occurred in borrow pits and vehicle tracks but not on undisturbed sites along the Canol Road east of Macmillan Pass in the Northwest Territories. Disturbed and undisturbed sites were within the bog birch/star reindeer lichen (Betula glandulosa/Cladonia alpestris)-moss tundra habitat type. Borrow pits and vehicle tracks were created during pipeline construction and were abandoned 48 years before this study. Undisturbed sites had higher cover and abundance of woody plants than disturbed sites [25]. Liverleaf wintergreen had a strong negative correlation (r = -0.50) with moderate and severe levels of mechanical site disturbances in boreal forests of central and northeastern British Columbia. Liverleaf wintergreen abundance was greatest on undisturbed and/or low-severity disturbed sites [19].

FIRE ECOLOGY

• FIRE ECOLOGY OR ADAPTATIONS
• POSTFIRE REGENERATION STRATEGY

Fire regimes: Fires are common in mixed-conifer, boreal, and subalpine forests that provide liverleaf wintergreen habitat. Average fire-return intervals reported for these forests range from 23 to 258 years.

Larsen [47] indicates that a mix of fire severities is possible in boreal forests. Early spring fires that typically burn when humus layers are wet are often low severity and kill few perennial plants. Severe fires require dry, deep fuels. Consumption of the humus layer by severe fires results in more plant death. Mixed-severity fires are common in mixed stands because the deep fuels that accumulate under spruce and are generally lacking under quaking aspen canopies.

A review of fire ecology studies in northern Idaho forests provides the range of average fire-return intervals in forests where liverleaf wintergreen occurs. Moist, subalpine habitats at 5,000 to 6,500 feet (1,500-2,000 m) dominated by subalpine fir, western hemlock, and mountain hemlock burn in low- to moderate-severity fires on average every 150 years. Stand-replacing fires are less frequent than mixed-severity fires. In moderately moist to moist grand fir-dominated forests, the mixed-severity fire-return interval averages range from 29 to over 116 years. Stand-replacing fire-return intervals average 138 to 203 years. The range of averages is a result of means reported from different areas and different studies. In moderately moist to moist western hemlock and western redcedar forests, average stand-replacing fire-return intervals range from 138 to over 258 years, and mixed-severity fires occur on average every 29 to 48 years [69].

In Canada's boreal and subarctic regions, summers are warm and dry, periods of sunlight are long, and the high cover of lichens and mosses dries readily. These factors produce readily burned surface fuels. In the Fort Simpson study area in the Northwest Territories where liverleaf wintergreen occurs, researchers sampled 21 stands, dated 43 fires, and found that the interval between fires was 6 to 100 years. The average fire-return interval was 23 years ± 10 (SD). Sites were dominated by mixed woodlands and pine (Pinus spp.) forests. Lightning was the major fire cause [65].

Mixed-conifer forests of the Teakettle Experimental Forest in the southern Sierra Nevada averaged 12 to 17 years between fires before 1865; since 1865, however, only 2 small fires have burned (references cited in [60]).

The following table provides fire-return intervals for plant communities where liverleaf wintergreen occurs. This list may not be inclusive for all plant communities in which liverleaf wintergreen occurs. 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".

FIRE EFFECTS

• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

Liverleaf wintergreen survival is likely dependent on depth of burn and soil temperatures produced. Liverleaf wintergreen's small size and infrequency in most habitats suggests that general plot or site descriptions of fire severity may not capture microsite differences that are likely important to liverleaf wintergreen survival.

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
It is nearly impossible to describe a typical liverleaf wintergreen response to fire. Sometimes liverleaf wintergreen is absent from burned sites; sometimes abundance is lower on burned than unburned sites; sometimes abundance is greater on burned than unburned sites. Some studies suggest that high-severity fires kill liverleaf wintergreen [71,91,92], and other studies report the highest cover of liverleaf wintergreen on sites burned in high-severity fires [49]. As suggested earlier, liverleaf wintergreen rarely occurs with high cover or frequency in any habitat, and likely sampling effects, microsite burn conditions, and the postfire growing environment affect liverleaf wintergreen's postfire response.

Researchers classified liverleaf wintergreen as a "survivor" after observing the first 15 years of postfire regeneration following 3 wildfires in northern Idaho. All fires were stand replacing and reduced organic soil to mineral ash [51]. Liverleaf wintergreen was classified as a "nonsurvivor" after monitoring the early postfire succession after the Sundance Fire in the Rocky Mountains of northern Idaho and northwestern Montana. The Sundance Fire was "high intensity" and burned with "firestorm conditions" in the western redcedar-western hemlock forest type [76].

Heating effects on seed bank: The following study suggests that liverleaf wintergreen seed can survive temperatures as high as 210 °F (100 °C) for at least 1 hour. Soil samples were collected from burned and unburned tufted hairgrass-sedge meadow sites in the Greater Yellowstone Ecosystem of Montana and Wyoming. No seedlings emerged from burned sites. Burned soil was collected in areas with complete overstory removal but not in areas of smoldering described as "deep ash ghosts of burned downfall". The density of liverleaf wintergreen seedlings that emerged from seed in unburned tufted hairgrass meadows was 53 seedlings/m². Soil samples had been cleaned of vegetative propagules. Seedlings also emerged from heat-treated unburned soils. Unburned soil samples treated for 1 hour of oven heating at 120 °F (50 °C), 210 °F (100 °C), and 300 °F (150 °C) had 106 seedlings/m², 27 seedlings/m², and 0 seedlings/m² emerge, respectively [4].

Absence from burned sites: Several studies report no liverleaf wintergreen on burned sites, not all of which burned in severe fires. Liverleaf wintergreen was absent from 1-year-old moderately and severely burned sites and 43-year-old burned sites along Jackson Lake in Grand Teton National Park, Wyoming. The frequency of liverleaf wintergreen in unburned Engelmann spruce (Picea engelmannii)-subalpine fir forest sites was 13% [2]. Liverleaf wintergreen was eliminated from logged and burned Douglas-fir forests in western Oregon and Washington. Before logging, forests were dominated by 120- to over 430-year-old trees. Understory species presence was evaluated before logging and periodically for up to 28 years after disturbances [22]. There may have been delayed mortality of liverleaf wintergreen on logged and slash burned Douglas-fir forests in Oregon's western Cascade Range. Before logging, liverleaf wintergreen cover was 0.1%, and frequency was 1.8% in old-growth (300-500 years old) stands. In the first postlogging year, liverleaf wintergreen cover was less than 0.05%, and frequency was 0.4%. In the 1st, 2nd, 3rd, and 4th years following slash burning, liverleaf wintergreen occurred only in trace amounts. In the 5th year after logging and slash burning, liverleaf wintergreen was not present on burned sites [11].

Present on burned sites: Liverleaf wintergreen abundance was not different on burned and unburned subalpine sites visited 10 years after fire in Alberta. There were no significant (P<0.05) differences in liverleaf wintergreen cover on 10-year-old burned and adjacent unburned subalpine white spruce-lodgepole pine forests on 2 burned sites. The fire near Banff National Park burned in late August and early September, spread at a daily average speed of 3.4 to 6.7 m/min. The fire near Jasper National Park burned in October, had a maximum spread rate of 26.8 m/min, and an average spread rate of 3.4 m/min [3]. In boreal mixed woods of southeastern Manitoba, sites burned 10 to 13 years earlier in a crown fire had 0.2% cover and 10% frequency of liverleaf wintergreen. Sites logged 10 to 14 years earlier had 0.4% cover and 11% frequency of liverleaf wintergreen [36].

Liverleaf wintergreen frequency decreased but cover increased 7 years after a June prescribed fire in spruce beetle-damaged white spruce forests in Alaska's Chugach National Forest. Prior to the fire, liverleaf wintergreen frequency was 24% and cover 5%. Seven years after the fire, which exposed the mineral soil in some areas, liverleaf wintergreen frequency was 6% and cover was 13%. Increased cover and decreased frequency could be explained by fewer large-sized plants after the fire [32].

Severely burned sites: Some studies report no liverleaf wintergreen on severely burned sites, but others report liverleaf wintergreen persistence on severely burned sites. Liverleaf wintergreen did not occur on unburned plots or plots burned in a "hot" prescribed fire in western larch (Larix occidentalis)-Douglas-fir forests in Montana's Lubrecht Experimental Forest. Spring and fall prescribed fires were evaluated 3 years later and described as "light", "medium", and "hot" burns [71,72]. Liverleaf wintergreen was absent from plots unburned for 70 years and from plots burned in "hot" fires that consumed litter, exposed mineral soil, and produced surface temperatures above 570 °F (300 °C). Liverleaf wintergreen averaged 1% cover 3 years after "medium" fires that consumed 50% of litter and duff and produced surface temperatures of 390 to 570 °F (200-300 °C). Cover averaged 0.5% on "light" burns where surface temperatures were less than 360 °F (180 °C) at the time of the fire, and less than 50% of litter was consumed [71].

In southeastern Manitoba, liverleaf wintergreen was present on scorched, "lightly" burned, 10-year-old burned, and mature unburned boreal mixed woods but was absent from severely burned sites. The Black River wildfire burned in early May 1999, and postfire vegetation was sampled for up to 4 years after fire. Fire severity was determined by assessing depth of burn. Scorching fires did not burn or just partially burned the litter layer. Light fires burned the litter layer but consumed little or no duff. Severe fires consumed the forest floor completely. Liverleaf wintergreen averaged 0.1% and 6% cover and frequency, respectively, on scorched sites. Cover and frequency averaged <0.1% and 3%, respectively, on lightly burned sites [91,92].

Liverleaf wintergreen cover was greatest on severely burned sites when unburned, "lightly" burned, and severely burned sites were compared 2 years following a spring fire in quaking aspen stands in northeastern Alberta. Liverleaf wintergreen cover averaged 1% on severely burned, 0.5% on "lightly" burned, and 0.3% on unburned sites. Unburned stands were over 120 years old. The researcher visually assessed fire severity. Severely burned sites had all aboveground vegetation consumed, and the top 2 to 4 inches (6-10 cm) of the organic layer oxidized. Light fires partially oxidized the top 0 to 0.8 inch (2 cm) of the organic layer of primarily mosses and litter. Liverleaf wintergreen did not emerge from vegetative propagules or seed in soil samples collected on burned or unburned sites [49]. Liverleaf wintergreen was present on 11-year-old burned stands but absent from unburned sites in a mixed-conifer forest in northwestern Oregon. The fire was described as severe, and unburned stands were an estimated 300 years old [58].

Repeatedly burned sites: Frequency of liverleaf wintergreen on unburned sites and sites burned more than once was much lower than once burned, once logged, and once logged and burned sites in seral shrub communities within the western redcedar-western hemlock forest type of northern Idaho. Sampled stands were 2 to 60 years old. A variety of sites was sampled, making it difficult to determine which affected liverleaf wintergreen frequency most: site conditions, disturbance type, or time since disturbance. A description of the sites where liverleaf wintergreen was most frequent is available in Site Characteristics. The table below summarizes study results [55].

MANAGEMENT CONSIDERATIONS

• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES
• OTHER MANAGEMENT CONSIDERATIONS

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

Cover value: Liverleaf wintergreen is a small plant that likely provides cover for only arthropods.

REFERENCES:

1. Anderson, J. P. 1959. Flora of Alaska and adjacent parts of Canada. Ames, IA: Iowa State University Press. 543 p. [9928]

2. Barmore, William J., Jr.; Taylor, Dale; Hayden, Peter. 1976. Ecological effects and biotic succession following the 1974 Waterfalls Canyon Fire in Grand Teton National Park. Research Progress Report 1974-1975. Unpublished report on file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 99 p. [16109]

3. Bentz, Jerry A. 1981. Effects of fire on the subalpine range of Rocky Mountain bighorn sheep in Alberta. Edmonton, AB: University of Alberta. 192 p. Thesis. [54956]

4. Clark, David Lee. 1991. The effect of fire on Yellowstone ecosystem seed banks. Bozeman, MT: Montana State University. 115 p. Thesis. [36504]

5. Cockerell, T. D. A. 1906. The Alpine Flora of Colorado. The American Midland Naturalist. 40(480): 861-873. [63653]

6. Cooper, W. S. 1916. Plant succession in the Mount Robson region, British Columbia. Journal of Ecology. 4(3/4): 196-198. [65678]

7. Cooper, William S. 1930. The seed-plants and ferns of the Glacier Bay National Monument, Alaska. Bulletin of the Torrey Botanical Club. 57(5): 327-338. [65666]

8. Cooper, William Skinner. 1923. The recent ecological history of Glacier Bay, Alaska: the present vegetation cycle. Ecology. 4(3): 223-246. [65668]

9. Corns, Ian G.; La Roi, George H. 1976. A comparison of mature with recently clear-cut and scarified lodgepole pine forests in the Lower Foothills of Alberta. Canadian Journal of Forest Research. 6(1): 20-32. [34970]

10. Doak, Daniel F.; Loso, Michael G. 2003. Effects of grizzly bear digging on alpine plant community structure. Arctic, Antarctic, and Alpine Research. 35(4): 421-428. [47428]

11. Dyrness, C. T. 1973. Early stages of plant succession following logging and burning in the western Cascades of Oregon. Ecology. 54(1): 57-69. [7345]

12. Gates, Frank C. 1942. The bogs of northern Lower Michigan. Ecological Monographs. 12(3): 213-254. [10728]

13. 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]

14. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]

15. Habeck, James R. 1968. Forest succession in the Glacier Park cedar-hemlock forests. Ecology. 49(5): 872-880. [6479]

16. Habeck, James; Stickney, Peter; Pfister, Robert; Noste, Nonan. 1980. Fire response classification of Montana forest species. The University of Montana, Missoula, MT. 15 p. [6993]

17. Haber, Erich. 1983. Morphological variability and flavonol chemistry of the Pyrola asarifolia complex (Ericaceae) in North America. Systematic Botany. 8(3): 277-298. [65657]

18. Haber, Erich. 1984. A comparative study of Pyrola minor x Pyrola asarifolia (Ericaceae) and its parental species in North America. Canadian Journal of Botany. 62(5): 1054-1061. [65653]

19. Haeussler, Sybille; Bedford, Lorne; Boateng, Jacob O.; MacKinnon, Andy. 1999. Plant community responses to mechanical site preparation in northern interior British Columbia. Canadian Journal of Forest Research. 29(7): 1084-1100. [38978]

20. Haeussler, Sybille; Kabzems, Richard. 2005. Aspen plant community response to organic matter removal and soil compaction. Canadian Journal of Forest Research. 35: 2030-2044. [61573]

21. Halpern, Charles B.; McKenzie, Donald; Evans, Shelley A.; Maguire, Douglas A. 2005. Initial responses of forest understories to varying levels and patterns of green-tree retention. Ecological Applications. 15(1): 175-195. [61472]

22. Halpern, Charles B.; Spies, Thomas A. 1995. Plant species diversity in natural and managed forests of the Pacific Northwest. Ecological Applications. 5(4): 913-934. [62677]

23. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005. Interagency fire regime condition class guidebook. Version 1.2, [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). Variously paginated [+ appendices]. Available: http://www.frcc.gov/docs/1.2.2.2/Complete_Guidebook_V1.2.pdf [2007, May 23]. [66734]

24. Harmon, Janice M.; Franklin, Jerry F. 1995. Seed rain and seed bank of third- and fifth-order streams on the western slope of the Cascade Range. Res. Pap. PNW-RP-480. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 27 p. [25915]

25. Harper, Karen A.; Kershaw, G. Peter. 1996. Natural revegetation on borrow pits and vehicle tracks in shrub tundra, 48 years following construction of the CANOL No. 1 Pipeline, N.W.T., Canada. Arctic and Alpine Research. 28(2): 163-171. [62701]

26. Harrington, H. D. 1964. Manual of the plants of Colorado. 2nd ed. Chicago, IL: The Swallow Press. 666 p. [6851]

27. Helm, D. J.; Allen, E. B. 1995. Vegetation chronosequence near Exit Glacier, Kenai Fjords National Park, Alaska, U.S.A. Arctic and Alpine Research. 27(3): 246-257. [26686]

28. Hickman, James C., ed. 1993. The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press. 1400 p. [21992]

29. Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific Northwest. Seattle, WA: University of Washington Press. 730 p. [1168]

30. Hitchcock, C. Leo; Cronquist, Arthur; Ownbey, Marion. 1959. Vascular plants of the Pacific Northwest. Part 4: Ericaceae through Campanulaceae. Seattle, WA: University of Washington Press. 510 p. [1170]

31. Holmgren, Noel H.; Holmgren, Patricia K.; Cronquist, Arthur. 2005. Intermountain flora: Vascular plants of the Intermountain West, U.S.A. Vol. 2, Part B: Subclass Dilleniidae. New York: The New York Botanical Garden. 488 p. [63251]

32. Holsten, Edward H.; Werner, Richard A.; Develice, Robert L. 1995. Effects of a spruce beetle (Coleoptera: Scolytidae) outbreak and fire on Lutz spruce in Alaska. Environmental Entomology. 24(6): 1539-1547. [26580]

33. Hulten, Eric. 1968. Flora of Alaska and neighboring territories. Stanford, CA: Stanford University Press. 1008 p. [13403]

34. 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]

35. Kartesz, John Thomas. 1988. A flora of Nevada. Reno, NV: University of Nevada. 1729 p. Dissertation. [In 2 volumes]. [42426]

36. Kemball, Kevin J.; Wang, G. Geoff; Dang, Qing-Lai. 2005. Response of understory plant community of boreal mixedwood stands to fire, logging, and spruce budworm outbreak. Canadian Journal of Botany. 83(12): 1550-1560. [63193]

37. Klinka, K.; Green, R. N.; Courtin, P. J.; Nuszdorfer, F. C. 1984. Site diagnosis, tree species selection, and slashburning guidelines for the Vancouver Forest Region, British Columbia. Land Management Report No. 25. Victoria, BC: Ministry of Forests, Information Services Branch. 180 p. [15448]

38. Klinka, K.; Krajina, V. J.; Ceska, A.; Scagel, A. M. 1989. Indicator plants of coastal British Columbia. Vancouver, BC: University of British Columbia Press. 288 p. [10703]

39. Klinka, Karel; Qian, Hong; Pojar, Jim; Meidinger, Del V. 1996. Classification of natural forest communities of coastal British Columbia, Canada. Vegetatio. 125(2): 149-168. [28530]

40. Krzic, M.; Newman, R. F.; Broersma, K. 2003. Plant species diversity and soil quality in harvested and grazed boreal aspen stands of northeastern British Columbia. Forest Ecology and Management. 182: 315-325. [51139]

41. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 166 p. [1384]

42. Lackschewitz, Klaus. 1991. Vascular plants of west-central Montana--identification guidebook. Gen. Tech. Rep. INT-227. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 648 p. [13798]

43. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1). Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior. 72 p. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. [66741]

44. LANDFIRE Rapid Assessment. 2007. Rapid Assessment potential natural vegetation groups (PNVGs): Associated vegetation descriptions and geographic distributions. Washington, DC: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; Arlington, VA: The Nature Conservancy. 84 p. [66533]

45. Larsen, J. A. 1929. Fires and forest succession in the Bitterroot Mountains of northern Idaho. Ecology. 10(1): 67-76. [6990]

46. Larsen, J. A. 1940. Site factor variations and responses in temporary forest types in northern Idaho. Ecological Monographs. 10(1): 1-54. [12933]

47. Larsen, James A. 1980. Boreal communities and ecosystems: local variation. In: Larsen, James A., ed. The boreal ecosystem. New York: Academic Press: 281-350. [64914]

48. Larsen, James A. 1980. Boreal communities and ecosystems: the broad view. In: Larsen, James A., ed. The boreal ecosystem. New York: Academic Press: 128-236. [64915]

49. Lee, Philip. 2004. The impact of burn intensity from wildfires on seed and vegetative banks, and emergent understory in aspen-dominated boreal forests. Canadian Journal of Botany. 82(10): 1468-1480. [51462]

50. Legare, Sonia; Bergeron, Yves; Leduc, Alain; Pare, David. 2001. Comparison of the understory vegetation in boreal forest types of southwest Quebec. Canadian Journal of Botany. 79(9): 1019-1027. [38854]

51. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings, Tall Timbers fire ecology conference and Intermountain Fire Research Council fire and land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496]

52. Martin, William C.; Hutchins, Charles R. 1981. A flora of New Mexico. Volume 2. Germany: J. Cramer. 2589 p. [37176]

53. Maycock, P. F.; Curtis, J. T. 1960. The phytosociology of boreal conifer-hardwood forests of the Great Lakes region. Ecological Monographs. 30(1): 1-36. [62820]

54. Moss, E. H. 1955. The vegetation of Alberta. Botanical Review. 21(9): 493-567. [6878]

55. Mueggler, Walter F. 1965. Ecology of seral shrub communities in the cedar-hemlock zone of northern Idaho. Ecological Monographs. 35(2): 165-185. [4016]

56. Munz, Philip A. 1974. A flora of southern California. Berkeley, CA: University of California Press. 1086 p. [4924]

57. Munz, Philip A.; Keck, David D. 1973. A California flora and supplement. Berkeley, CA: University of California Press. 1905 p. [6155]

58. Neiland, Bonita J. 1958. Forest and adjacent burn in the Tillamook Burn area of northwestern Oregon. Ecology. 39(4): 660-671. [8879]

59. Nelson, David L.; Krebill, Richard G. 1982. Occurrence and effect of Chrysomyxa pirolata cone rust on Picea pungens in Utah. The Great Basin Naturalist. 42(2): 262-272. [15938]

60. North, Malcolm; Oakley, Brian; Fiegener, Rob; Gray, Andrew; Barbour, Michael. 2005. Influence of light and soil moisture on Sierran mixed-conifer understory communities. Plant Ecology. 177: 13-24. [64836]

61. Pojar, Jim; MacKinnon, Andy, eds. 1994. Plants of the Pacific Northwest coast: Washington, Oregon, British Columbia and Alaska. Redmond, WA: Lone Pine Publishing. 526 p. [25159]

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

63. Roach, A. W. 1952. Phytosociology of the Nash Crater lava flows, Linn County, Oregon. Ecological Monographs. 22(3): 169-193. [8759]

64. Roland, A. E.; Smith, E. C. 1969. The flora of Nova Scotia. Halifax, NS: Nova Scotia Museum. 746 p. [13158]

65. Rowe, J. S.; Bergsteinsson, J. L.; Padbury, G. A.; Hermesh, R. 1974. Fire studies in the Mackenzie Valley. ALUR 73-74-61. Ottawa, ON: Canadian Department of Indian and Northern Development. 123 p. [50174]

66. Rundel, Philip W.; Parsons, David J.; Gordon, Donald T. 1977. Montane and subalpine vegetation of the Sierra Nevada and Cascade Ranges. In: Barbour, Michael G.; Major, Jack, eds. Terrestrial vegetation of California. New York: John Wiley & Sons: 559-599. [4235]

67. Rydberg, Per Axel. 1906. Flora of Colorado. Bulletin 100. Fort Collins, CO: Colorado Agricultural College, Agricultural Experiment Station. 448 p. [63874]

68. Seymour, Frank Conkling. 1982. The flora of New England. 2nd ed. Phytologia Memoirs 5. Plainfield, NJ: Harold N. Moldenke and Alma L. Moldenke. 611 p. [7604]

69. Smith, Jane Kapler; Fischer, William C. 1997. Fire ecology of the forest habitat types of northern Idaho. Gen. Tech. Rep. INT-GTR-363. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 142 p. [27992]

70. St. John, Harold; Warren, Fred A. 1937. The plants of Mount Rainier National Park, Washington. The American Midland Naturalist. 18(6): 952-985. [62707]

71. Stark, N.; Steele, R. 1977. Nutrient content of forest shrubs following burning. American Journal of Botany. 64(10): 1218-1224. [2224]

72. Steele, Robert. 1976. Smoke considerations associated with understory burning in larch/ Douglas-fir. Proceedings, Montana Tall Timbers fire ecology conference and Intermountain Fire Research Council fire & land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 597-607. [19033]

73. Steen, O. A.; Roberts, A. L. 1988. Guide to wetland ecosystems of the Very Dry Montane Interior Douglas-fir Subzone, Eastern Fraser Plateau Variant (IDFb2) in the Cariboo Forest Region, British Columbia. Williams Lake, BC: British Columbia Ministry of Forests and Lands. 101 p. [53384]

74. Stickney, Peter F. 1986. First decade plant succession following the Sundance forest fire, northern Idaho. Gen. Tech. Rep. INT-197. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 26 p. [2255]

75. 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, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 10 p. [20090]

76. Stickney, Peter F.; Campbell, Robert B., Jr. 2000. Data base for early postfire succession in Northern Rocky Mountain forests. Gen. Tech. Rep. RMRS-GTR-61-CD, [CD-ROM]. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. On file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. [43743]

77. Strong, W. L. 2004. Secondary vegetation and floristic succession with a boreal aspen (Populus tremuloides Michx.) clearcut. Canadian Journal of Botany. 82(11): 1576-1585. [52068]

78. Strong, W. L.; LaRoi, G. H. 1986. A strategy for concurrently monitoring the plant water potentials of spatially separate forest ecosystems. Canadian Journal of Forest Research. 16(2): 346-351. [10805]

79. Sullivan, Thomas P.; Sullivan, Druscilla S.; Lindgren, Pontus M. F. 2000. Small mammals and stand structure in young pine, seed-tree, and old-growth forest, Southwest Canada. Ecological Applications. 10(5): 1376-1383. [65673]

80. Suominen, Otso; Danell, Kjell; Bryant, John P. 1999. Indirect effects of mammalian browsers on vegetation and ground-dwelling insects in an Alaskan floodplain. Ecoscience. 6(4): 505-510. [65654]

81. Taylor, R. F. 1932. The successional trend and its relation to second-growth forests in southeastern Alaska. Ecology. 13(4): 381-391. [10007]

82. Topik, Christopher; Hemstrom, Miles A., comps. 1982. Guide to common forest-zone plants: Willamette, Mt. Hood, and Siuslaw National Forests. R6-Ecol 101-1982. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 95 p. [3234]

83. USDA Natural Resources Conservation Service. 2017. PLANTS Database, [Online]. U.S. Department of Agriculture, Natural Resources Conservation Service (Producer). Available: https://plants.usda.gov/. [34262]

84. Van Cleve, K.; Viereck, L. A.; Dyrness, C. T. 1996. State factor control of soils and forest succession along the Tanana River in interior Alaska, U.S.A. Arctic and Alpine Research. 28(3): 388-400. [65672]

85. van Denack, Julia Marie. 1961. An ecological analysis of the sand dune complex in Point Beach State Forest, Two Rivers, Wisconsin. Botanical Gazette. 122(3): 155-174. [49642]

86. Viereck, L. A.; Dyrness, C. T.; Foote, M. J. 1993. An overview of the vegetation and soils of the floodplain ecosystems of the Tanana River, interior Alaska. Canadian Journal of Forest Research. 23(5): 889-898. [21887]

87. Viereck, Leslie A. 1966. Plant succession and soil development on gravel outwash of the Muldrow Glacier, Alaska. Ecological Monographs. 36(3): 181-199. [12484]

88. Viereck, Leslie A. 1989. Flood-plain succession and vegetation classification in interior Alaska. In: Ferguson, Dennis E.; Morgan, Penelope; Johnson, Frederic D., comps. Proceedings--land classifications based on vegetation: applications for resource management; 1987 November 17-19; Moscow, ID. Gen. Tech. Rep. INT-257. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 197-203. [6959]

89. Voss, Edward G. 1996. Michigan flora. Part III: Dicots (Pyrolaceae--Compositae). Bulletin 61. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 622 p. [30401]

90. Walford, Gillian M. 1993. Spatial variation in riparian vegetation along the Animas River, Colorado. Laramie, WY: University of Wyoming. 99 p. Thesis. [53679]

91. Wang, G. Geoff; Kemball, Kevin J. 2003. The effect of fire severity on early development of understory vegetation following a stand replacing wildfire--3B.2, [Online]. In: Proceedings, 2nd international wildland fire ecology and fire management congress held concurrently with the 5th symposium on fire and forest meteorology; 2003 November 16-20; Orlando, FL. Boston, MA: American Meteorology Society (Producer): Available: http://ams.confex.com/ams/FIRE2003/techprogram/paper_65430.htm [2006, October 27]. [64194]

92. Wang, G. Geoff; Kemball, Kevin J. 2005. Effects of fire severity on early development of understory vegetation. Canadian Journal of Forest Research. 35(2): 254-262. [60329]

93. Weber, William A. 1987. Colorado flora: western slope. Boulder, CO: Colorado Associated University Press. 530 p. [7706]

94. Weber, William A.; Wittmann, Ronald C. 1996. Colorado flora: Eastern slope. 2nd ed. Niwot, CO: University Press of Colorado. 524 p. [27572]

95. Welsh, Stanley L.; Atwood, N. Duane; Goodrich, Sherel; Higgins, Larry C., eds. 1987. A Utah flora. The Great Basin Naturalist Memoir No. 9. Provo, UT: Brigham Young University. 894 p. [2944]

96. Zoladeski, C. A.; Delorme, R. J.; Wickware, G. M.; Corns, I. G. W.; Allan, D. T. 1998. Forest ecosystem toposequences in Manitoba. Special Report 12. Edmonton, AB: Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre. 63 p. [35768]