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Corydalis sempervirens

Table of Contents

• 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 COMMON NAMES TAXONOMY SYNONYMS LIFE FORM
	Photo by Rob Routledge, Sault College, Bugwood.org

DISTRIBUTION AND OCCURRENCE

• GENERAL DISTRIBUTION
• SITE CHARACTERISTICS AND PLANT COMMUNITIES

Distribution of rock harlequin. Map courtesy of the Flora of North America Association, 7 December 2012.

Rock harlequin occurs throughout Canada, but it is rare in the western United States, occurring only in Alaska and Glacier National Park in northwestern Montana [23,45]. In the eastern United States, rock harlequin occurs in the Great Lakes region and New England, and it ranges south along the Blue Ridge Mountains into extreme northwestern Georgia [104].

States and provinces [92]:
United States: AK, CT, GA, IA, IL, IN, KY, MA, MD, ME, MI, MN, MT, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WI, WV
Canada: AB, BC, LB, MB, NB, NF, NS, NT, NU, ON, PE, QC, SK, YT

SITE CHARACTERISTICS AND PLANT COMMUNITIES:
Rock harlequin is characteristic of 2 habitats [14]: rocky sites on dry, well-drained, often acidic soils [10,68]; and recently disturbed sites, including burned areas (see Plant response to fire). It occurs in climates with cold winters and cool summers, having mean January temperatures of -15 to 18 °F (-26 to -8 °C) and mean July temperatures of 63 to 66 °F (17-19 °C) [1,35,64]. Rock harlequin occurs from near sea level in the northeastern United States [68] to over 5,200 feet (1,600 m) in the southern Appalachians [103].

Site characteristics: Sites with rock harlequin in the eastern United States are often described as dry mesic [8,55] to dry [8,55,56,57,84,106]. It occurred on fresh to moist sites in a jack pine stand in Saskatchewan that was regenerating following fire [16]. In the Kenai Mountains of Alaska, rock harlequin was negatively associated (r = -0.21) with site moisture [12].

Rock harlequin is a characteristic species of exposed [18,37,68], rocky areas [34,56,59,68,70,81,89,104], ledges [37,84,99], and cliffs [31,68,72], from the Carolinas [72] to Canada [81] and Alaska [34]. Soils supporting rock harlequin have been described as coarse [47,68,99], shallow [15,53,68,70,106], well to excessively drained [10,37,68,106], and acidic [10,47,68,70]. Rock harlequin is a component of vegetation associated with outcrops [10,14,18,31,42,53,68,72] and talus slopes [21,47,70]. It is listed as a species of exfoliating granitic domes and granitic gneiss in the Appalachians [102], including the Blue Ridge [5] and portions of North Carolina [60,79]. Wiser [103] classified rock harlequin as a rock outcrop obligate in the southern Appalachians. It also occurs in moss mats in southern Ontario granite barrens [15] and on Beaver Island in Lake Superior, Minnesota [39].

Rock harlequin is often found on recently disturbed sites including harvested forests [74], rights-of-way [57], roadsides [34,99], and areas cleared for cultivation [19,86]. Rock harlequin is most prominent in these areas within about 2 years of disturbance [14,19,99]. For information on occurrence of rock harlequin in burned areas see Plant response to fire.

Plant communities: Rock harlequin occurs during early postdisturbance years in a variety of coniferous and mixedwood boreal forest communities in Alaska [74,93,95] and Canada [35,65,83]. In the eastern United States it also occupies deciduous woodlands [5,8,47,60,68,70]. Many of the communities where rock harlequin occurs in the eastern United States are associated with rock outcrops or exposed bedrock. Rock harlequin is an indicator of the eastern redcedar (Juniperus virginiana)-rock harlequin cliff sparse vegetation community on the Pennsylvania and New Jersey border [68]. See Table 1 for a list of communities rock harlequin occurs in throughout its range. See the Fire Regime Table for a list of plant communities in which rock harlequin may occur and information on the fire regimes associated with those communities.

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

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

Botanical description Raunkiaer life form
	Photo by Arthur Haines, New England Wild Flower Society

Botanical description: This description includes characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [32,33,34,59,72,81,84,99]). Rock harlequin is a native, biennial [14,15,31,34,72,81] or annual [14,15,34] forb that grows 8 to 51 inches (20-130 cm) tall [31,32,72,99]. Flowers have united petals with a single spur [31,59,72,81]. The leaves have 3 to 5 primary segments that are 7 to 20 mm long and 3 to 6 mm wide [31,72]. The fruit is an erect [31,34,72,84], elongated [59], dry, dehiscent [33] capsule from 0.8 to 2 inches (2-5 cm) long [31,72,81,84]. Each fruit contains about 25 seeds [33], about 1 to 1.5 mm wide [31,84,99]. The average weight of 1,000 rock harlequin seeds from a single plant in Minnesota was 0.460 grams [87].

Raunkiaer [73] life form:
Hemicryptophyte
Therophyte

SEASONAL DEVELOPMENT:
Rock harlequin flowers from April [104] through September [37]. Flowering occurs earliest in the Appalachians [31,72,104] and latest in New England [84] and New York [37]. In Montana, rock harlequin flowers in July [45]. It fruits from August to September in the Adirondack Mountains [37]. In southern Ontario [15] and Michigan [99] reappearance of rock harlequin in autumn suggests that seeds from early blooming plants may germinate and mature in the same growing season. Rock harlequin may also overwinter as a rosette and flower in its second year [14].

REGENERATION PROCESSES:
Rock harlequin reproduces from seeds. Although the germination requirements of rock harlequin have not been documented [98] and germination without heat treatment has been observed [14], the occurrence of rock harlequin following fire (see Plant response to fire) suggests germination may be enhanced by heat exposure.

Pollination and breeding system: Rock harlequin may outcross but has perfect flowers [31,33,34,59,72,99] and is fully self-compatible. The fittest plants in greenhouse and field experiments were those that were outcrossed [14]. The flowers of rock harlequin are pollinated by wind, ants [35], and possibly other insects [14]. The flowers produce nectar and are visited by numerous insects including bumblebees and skipper butterflies [14].

Seed production: Rock harlequin flowers in either the 1st or 2nd year [14]. Capsules typically produce about 20 [14] to 25 [33] seeds each.

Seed dispersal: Gravity [2], wind, and ants [35] have been reported as the dispersal mechanisms of rock harlequin seed.

Seed banking: Rock harlequin was categorized as a species with an aboveground seed bank [44] and long-lived propagules [4]. It apparently banks its seed in the forest floor for decades or even centuries, until germination is triggered by disturbance, exposure, and/or soil warming [51]. The thick, hard seed coat may contribute to this potentially long period of viability [97].

Viable rock harlequin seeds have been found in soil from forests that have not burned in decades [3,27]. Although mature rock harlequin was absent from an 80-year-old mixed white spruce-jack pine stand in central Alberta, 22 rock harlequin germinants/m² emerged from organic soil samples taken from the site [27]. At the Boundary Waters Canoe Area in Minnesota, rock harlequin seed in soil samples from a jack pine-red pine stand that had not burned in 30 years had a germination rate of 35% [3].

Rock harlequin seeds have been found in the soil of mature and old-growth forests. A maximum density of 200 rock harlequin seeds/m² was found in samples from 4 old-growth deciduous forest sites in southwestern Quebec [43]. Rock harlequin seeds were found in soil samples taken from open lichen woodlands comprised of 42- to 180-year-old black spruce, white spruce, and/or jack pine stands in Northwest Territories [35], and in the organic layer of a soil sample from an approximately 50-year-old boreal mixedwood stand in northwestern Ontario [71].

Germination: As of this writing the germination requirements of rock harlequin seeds have not been documented [98]; however, circumstantial evidence suggests that germination is enhanced by heat [1,67] (see Fire adaptations).

Average germination rates of rock harlequin seed in greenhouse and field experiments were 36.8% for seed produced by selfing and 43.3% for outcrossed seed. These rates were observed without heat treatments [14].

Seedling establishment and plant growth: Little information was available (as of 2012) regarding seedling establishment and growth of rock harlequin. In boreal forest ecosystems of Canada, rock harlequin is categorized as a species that invades disturbed sites and grows rapidly [82].

Vegetative regeneration: There is no evidence that rock harlequin regenerates vegetatively.

SUCCESSIONAL STATUS:
Rock harlequin is a pioneer species in secondary succession, particularly after fires. It is most abundant for a few years immediately after disturbances such as wildfire [51]. It develops best in full light and is characterized by rapid establishment and growth [82]. It is considered an early successional species of eastern white pine communities in northern Minnesota [86], white spruce upland boreal forests of interior Alaska [74,93], and paper birch-black spruce in northern Saskatchewan [83]. Rock harlequin is generally present for 3 to 6 years following fire [1,24,36]. See Plant response to fire for more detail regarding its postfire occurrence.

Although rock harlequin is commonly associated with openings and grows best in full sunlight [77], it does occur in partially shaded and shaded communities. It is associated with openings in the Blue Ridge [104], New England [84], and throughout Canada [81]; and it is considered shade intolerant in the Adirondack Mountains [37]. It occurs in several open woodland communities including red oak woodlands in North Carolina [60] and pitch pine mixed hardwood communities or hickory-eastern redcedar woodlands in Pennsylvania [68]. Rock harlequin has been reported to develop best in full sunlight in boreal ecosystems of Canada [82]. In Queens County Nova Scotia, rock harlequin grew taller in open quadrats within the boundary of a severe summer fire than in quadrats that were covered [54]. Rock harlequin sometimes occurs in shaded communities, such as partially shady and shady sites within dry to dry mesic oak savannas [8] and cedar glades in Wisconsin [22], shaded rock outcrops in Georgia [101], and chestnut oak forests with closed to partially open canopies in Pennsylvania [68].

FIRE EFFECTS AND MANAGEMENT

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

FIRE EFFECTS:
Immediate fire effect on plant: Fire generally kills rock harlequin plants, but not its seed (see Fire adaptations). On a pine-oak forest on the George Washington National Forest in West Virginia, rock harlequin was rare on upper slopes of northeastern aspects of the Dunkle knob site before fire and was absent after fire [53].

Postfire regeneration strategy [88]:
Ground residual colonizer (on site, initial community)
Secondary colonizer (on- or off-site seed sources)

Fire adaptations and plant response to fire:

• Fire adaptations
• Plant response to fire

Fire adaptations: Rock harlequin establishes from soil-stored seed after fire. Rock harlequin germinated from buried seed after a spring wildfire in white spruce stands of interior Alaska [94]. It established from seed following fires in the subboreal spruce zone of east-central British Columbia [28], a black spruce-jack pine stand in northeastern Minnesota [36], and on sites in the Superior National Forest in Minnesota [2]. Rock harlequin germinated from buried seed after slash burning in east-central British Columbia [29]. It occurred in both uncovered and covered quadrats that were established immediately following a severe summer fire in red spruce-hardwood community in Queen's County, Nova Scotia [54]. Although germination and establishment during early postfire years is well documented (see Plant response to fire), greenhouse and field trials suggest a heat treatment is not required for germination [14]. Little else is known about germination requirements of rock harlequin seed [98]. See Seed banking for more detail on soil-stored rock harlequin seed.

Plant response to fire: Rock harlequin is characteristic of recently burned areas and is most abundant for a few years immediately after wildfire [51]. It occurred within a few months of a spring wildfire in white spruce stands of interior Alaska [94] and germinated within a few weeks of fire on another site in Alaska [97]. It was positively associated (r=0.23) with areas that were burned under prescription in the Kenai Mountains of Alaska [12]. Rock harlequin' occurrence on burned sites and absence from unburned sites was noted in the Superior National Forest in northeastern Minnesota [2], the subboreal spruce zone of east-central British Columbia [28], white spruce-aspen and white spruce-balsam fir stands in north-central Alberta [48], black spruce stands in interior Alaska [11,50], and aspen stands near Fairbanks, Alaska [95,96]. It has been categorized as a fire evader [4,25,76] and a rapid-growth pioneer [4].

Rock harlequin often occurs on burned sites despite being absent before the fire. For instance, rock harlequin occurred in a right-of-way 3 years after fire in the subarctic upland black spruce region in central Northwest Territories, although it was absent before the fire [62]. It was also absent before and present after prescribed burning in black oak sand savannas at Hoosier Prairie Nature Preserve [6,7]. Rock harlequin was present on recently burned jack pine sites in northern lower Michigan, but did not occur on sites that were clearcut and not burned [1].

Rock harlequin's postfire establishment is not related to fire severity or season. It occurred after low [11,80,100], moderate [11,80], and high-severity [44,90] fires and after spring [64], summer [64,66,85], and autumn [90] fires.

Rock harlequin is most common in the first 4 postfire years [30,36,44,50,58,78,91,100], with abundance typically peaking in the first [17,63] or second [65,94] postfire year. This trend has been observed in the boreal forest of northwestern Ontario [20], in the subboreal spruce zone of east-central British Columbia [28,29] (see Table 2 below), in boreal forests near the border of north-central British Columbia and south-central Yukon [65], on white spruce slopes of interior Alaska [94,105], in aspen stands near Fairbanks, Alaska [96], and in jack pine stands in Saskatchewan [17] and northern lower Michigan [1]. Rock harlequin was common in aspen-dominated boreal forest 2 years after wildfire, but absent from similar stands 34 years after wildfire [38].

Rock harlequin was a significant indicator of burned-unsalvaged forest (Kurulock 2004 cited by [49]), and postfire salvage logging may reduce its abundance in some cases. In aspen-dominated, boreal mixedwood forest in east-central Alberta, rock harlequin cover was significantly (P<0.01) greater 2 years after wildfire in unlogged stands (0.52%) than in salvage-logged stands (0.03%) [38]. In contrast, 2 years following a 250,000-ha, mixed-severity, May wildfire in northeastern Alberta, rock harlequin occurred in both patch-retention and single-tree retention salvage logging treatments in boreal mixedwood forest, but not in unsalvaged controls. However, it did occur in burned, unsalvaged jack pine and jack pine-black spruce forest types within the burned area [49].

FUELS AND FIRE REGIMES:
Rock harlequin contributes little to fuel loads and is a component of communities with varied fire regimes.

Fire regimes: Because rock harlequin occurs in a variety of communities, it is subject to many different fire regimes ranging from surface fires with 4-year return intervals in Great Lakes pine barrens, to infrequent, stand-replacement fires in communities such as southern Appalachian high-elevation forest or northern hardwood-spruce. For information on fire regimes of communities were rock harlequin occurs, see the Fire Regime Table and FEIS reviews of dominant species such as black spruce, white spruce, jack pine, eastern redcedar, and red oak. Find further 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 MANAGEMENT CONSIDERATIONS:
Throughout much of its range, rock harlequin occurs only on recently burned sites [6,62]. Since its abundance declines 3 to 6 years after fire [1] (see Plant response to fire), it is unlikely to occur in areas where fires are excluded. Rock harlequin is likely to establish after fire in areas where it formerly occurred, if viable seed is still present in the soil. Recently burned areas can be monitored to determine whether the potential for viable populations remains.

MANAGEMENT CONSIDERATIONS

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

Palatability and nutritional value: Rock harlequin was 1 of 4 species with high nutrient content due to rapid uptake of soil nutrients after a spring wildfire in white spruce stands of interior Alaska [94].

Cover value: No information is available on this topic.

VALUE FOR REHABILITATION OF DISTURBED SITES:
Rock harlequin has potential for use in rehabilitation of disturbed sites. It grows well on disturbed sites and provides erosion protection, yet it is not competitive, thus allowing natural succession to proceed. Germination characteristics and requirements have not been tested in this species [75].

OTHER USES:
No information is available on this topic.

OTHER MANAGEMENT CONSIDERATIONS:
Several articles discuss the resistance of rock harlequin to glyphosate (e.g., [69]).

APPENDIX: FIRE REGIME TABLE

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