Number of burns
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [41,63,73]).
Beetleweed is a perennial forb or subshrub that reaches 2 to 12 inches (6-30 cm) in height [41,73]. Its evergreen leaves are heart-shaped, thick, and glossy. They are singular, arising from a 1- to 10-inch (3-25 cm)- long petiole [52,63]. Leaf life span is 18 months [56]. Numerous small perfect flowers are 3 to 4 mm wide, and are arranged in a spike-shaped raceme on an 8- to 16-inch (20-40 cm) flower stem. Seeds are <1 mm long. They are contained in a small capsule. Each capsule contains "several to numerous" seeds. Beetleweed is rhizomatous. Roots are fibrous [52,63].
Beetleweed has 2 races, diploid and tetraploid, that are morphologically distinct [2,3,64]. Leaf morphology differs geographically and genetically among populations, with mountainous and southern populations (which are mostly tetraploid) having large leaves, and northern populations (mostly diploid) having small leaves [2,30]. Under best growing conditions (see Site Characteristics), leaves of diploid beetleweed are 4 inches (10 cm) across, while tetraploid beetleweed's leaves may reach 6 inches (20 cm) across. On poor sites, the 2 races may both have small leaves and be indistinguishable in the field [2].
Beetleweed occurs in the Appalachian Mountain, Piedmont, and Coastal Plain regions of the eastern United States. It is most common at the center of its distribution in the southern Appalachian Mountains. Its northernmost occurrence is in New York [30,41,51,63] and northeastern Massachusetts [47,51]. Beetleweed distribution apparently skirts Pennsylvania, where it had not been collected (as of 2005). Its distribution continues south from Ohio to northern Alabama and Georgia [41,51,63]. Beetleweed may be nonnative in New York, Massachusetts, Washington, DC., and Ohio (review by [51]). Plants database provides a state distributional map of beetleweed.
There are 2 races of beetleweed. Their distributions mostly overlap. See General Botanical Characteristics and Site Characteristics for details on morphologies and habitats, respectively, distinguishing beetleweed races.
Fire adaptations: As of this writing (2006), no literature specifically addressed beetleweed fire adaptations. It is likely that beetleweed's rhizomes survive fire, as beetleweed has been found on burned sites in the 1st postfire growing season [16].
Laboratory and field experiments suggest that extreme heat or cold shock during flowering can induce polyploidy [54,64]. Baldwin [2] suggested that repeated fire disturbances and/or glaciation may have played an evolutionary role in the development of beetleweed tetraploidy.
FIRE REGIMES: Fire was historically important in maintaining oak-pine and high-elevation, xeric pine forests where beetleweed occurs [46,58,71]. In the Appalachian Mountains, where beetleweed is most common, such communities experienced both stand-replacing and mixed-severity fires. In Great Smoky Mountain National Park, occurrence of both anthropogenic and natural fires increased with elevation, and lightning fires were most frequent on xeric, high-elevation sites [5,33] where beetleweed is common [13,58]. Whittaker [72] suggested that xeric, even-aged pine forests of the Great Smoky Mountains were mostly maintained by severe fire that replaced the existing stand; however, as the even-aged stand matured, pine mortality created small openings where gap succession occurred. He also stated the "fire alone does not produce these pine stands" [72]. Hurricanes, tornadoes, and less severe wind storms also maintained seral pine and oak-pine stands [46,65]. Time between stand-replacing fires varied between sites and among pine species.
Some pine and oak-pine communities dominated by serotinous pines have moderate to long fire-return intervals. Table Mountain pine historically experienced medium-return interval, stand-replacement fires [66]. Barden [3] documented a Table Mountain pine stand on Glass Mountain, North Carolina, that established after a fire 87 years previously. Fire may be very infrequent on some sites: Zobel [74] suggests that Table Mountain pine stands on rocky outcrops or shale slopes, where hardwood regeneration is poor, are self-sustaining, and rarely if ever experience fire. On sites where succession proceeds to understory hardwoods, understory burning probably helped keep the hardwoods in check [46].
In a 1935 survey of a shortleaf pine-chestnut oak community in the Cumberland Mountains of Kentucky, Braun [6] noted and 0.5- to 1-inch (cm) duff layer of pine, oak, and mountain-laurel leaves.
Mesic pine forests: Not all pine forests where beetleweed occurs have stand-replacement FIRE REGIMES. Longleaf and other nonserotinous pines historically experienced frequent surface fires [70]. Peet and Allard [50] state that longleaf pine-blackjack oak/mountain-laurel/beetleweed communities of North Carolina require "exceptionally high fire frequency." Occurring on mesic, north-facing slopes, these communities are successionally replaced relatively quickly when fire is excluded [50].
Heath balds where beetleweed is common to dominant in the understory were apparently maintained by stand-replacing fire, landslides, extreme weather conditions, and/or windthrow in presettlement times. Logging in the 20th Century stopped tree invasion onto the balds. Possibly due to highly acidic soils, some balds appear stable despite lack of disturbance such as fire [10,25,72]. On other and possibly most balds, however, repeated fires may have been the primary disturbance that maintained the shrubland [7,25]. Cain [10] found that all of the heath balds he sampled in the Great Smoky Mountains had burned multiple times. For heath bald types, fires in balds undergoing successional replacement by red spruce are probably most severe [25].
The following table provides fire return intervals for plant communities and ecosystems where beetleweed is important. 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".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) maple-beech-birch Acer-Fagus-Betula spp. >1,000 silver maple-American elm Acer saccharinum-Ulmus americana <5 to 200 sugar maple Acer saccharum >1,000 sugar maple-basswood Acer saccharum-Tilia americana >1,000 beech-sugar maple Fagus spp.-Acer saccharum >1,000 black ash Fraxinus nigra <35 to 200 yellow-poplar Liriodendron tulipifera <35 [70] northeastern spruce-fir Picea-Abies spp. 35-200 [18] southeastern spruce-fir Picea-Abies spp. 35 to >200 [70] red spruce* Picea rubens 35-200 [18] shortleaf pine Pinus echinata 2-15 shortleaf pine-oak Pinus echinata-Quercus spp. <10 longleaf pine-scrub oak Pinus palustris-Quercus spp. 6-10 Table Mountain pine Pinus pungens <35 to 200 [70] red-white-jack pine* Pinus resinosa-P. strobus-P. banksiana 10-300 [18,37] pitch pine Pinus rigida 6-25 [8,38] pocosin Pinus serotina 3-8 eastern white pine Pinus strobus 35-200 eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200 eastern white pine-northern red oak-red maple Pinus strobus-Quercus rubra-Acer rubrum 35-200 loblolly-shortleaf pine Pinus taeda-P. echinata 10 to <35 Virginia pine Pinus virginiana 10 to <35 Virginia pine-oak Pinus virginiana-Quercus spp. 10 to <35 sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana <35 to 200 [70] aspen-birch Populus tremuloides-Betula papyrifera 35-200 [18,70] black cherry-sugar maple Prunus serotina-Acer saccharum >1,000 oak-hickory Quercus-Carya spp. <35 [70] oak-juniper woodland (Southwest) Quercus-Juniperus spp. <35 to <200 [49] northeastern oak-pine Quercus-Pinus spp. 10 to <35 [70] southeastern oak-pine Quercus-Pinus spp. <10 white oak-black oak-northern red oak Quercus alba-Q. velutina-Q. rubra <35 northern pin oak Quercus ellipsoidalis <35 bear oak Quercus ilicifolia <35 chestnut oak Quercus prinus 3-8 northern red oak Quercus rubra 10 to <35 post oak-blackjack oak Quercus stellata-Q. marilandica <10 black oak Quercus velutina <35 eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis >200 [70] eastern hemlock-white pine Tsuga canadensis-Pinus strobus x = 47 [15] elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. <35 to 200 [18,70] *fire return interval varies widely; trends in variation are noted in the species reviewBeetleweed evolved under a wide variety of FIRE REGIMES, and information of its rate of postfire recovery is sparse for all plant communities in which it occurs (as of 2006). How quickly beetleweed recovers from fire will vary with fire regime, plant community, fuels, and fire season. Harvest history also undoubtedly affects beetleweed's ability to recover after fire. Because harvesting (see Other Management Considerations) reduces beetleweed's photosynthetic capacity and biomass, populations that have been heavily harvested probably have reduced rhizome carbohydrate reserve. Therefore, they have reduced ability to sprout and produce seed compared to unharvested populations. Data are need on 1) sustainable levels of beetleweed harvest and 2) interactive effects of harvesting and fire.
Beetleweed leaves may help generate severe fires that provide important ecological benefits. Turrill and others [66] report that in Table Mountain/mountain-laurel/beetleweed communities on the Chattahoochee National Forest of Georgia, groundlayer beetleweed and blueberries (Vaccinium spp.) promote "hot" surface fires that remove even deep build-ups of litter and organic matter under dry conditions. In turn, tall mountain-laurel shrubs can become ladder fuels that carry beetleweed and blueberry-fueled surface fires up to the serotinous cones of Table Mountain pine, aiding in the pine's postfire regeneration [66].
Elliot and Clinton [21] provide allometric equations for predicting aboveground dry weight of beetleweed in the southern Appalachian Mountains.Beetleweed occurs in mesic and xeric forested sites in the Appalachian mountains, piedmont, and coastal plains [28,31,52,59,63]. Baldwin [2] described an ideal beetleweed site as "a shaded, mesic habitat in the mountains with a soil that is rich, acid, and humus-covered."
Elevation: Precise elevational data are sparse for beetleweed. However, beetleweed is reported on sites with a wide elevational range, from low-elevation coastal plains and highest-elevation mountain peaks. In Virginia, for example, it is reported on low-elevation coastal plains (~0-70 feet (20 m)) and at 1,940 feet (591 m) in a Carolina hemlock forest [2,57]. Beetleweed has been collected on the highest peaks of the Appalachian Mountains: 5,964 feet (1,818 m) on Grandfather Mountain in North Carolina and 5,200 feet (1,600 m) on Mt. LeConte in Tennessee [2].
Tetraploid populations of beetleweed occur throughout the distribution of diploid beetleweed. They also occur on the Virginia coastal plain, where diploid populations do not occur. Additionally, tetraploid beetleweed are more common at high elevations than diploid beetleweed [2].
Soils: Beetleweed commonly occurs on rocky or sandy acidic soils on slopes, ridges, and mountain hillsides [74]. Best growth occurs on moist, acidic soils, although beetleweed occurs on dry soils in chestnut oak and a few other habitats (review by [25]). In Kentucky, beetleweed has been noted on soils with a pH as low as 3.9 [6].
Climate: Considerable climatic diversity is found in beetleweed's range. Climate ranges from subtropical along the southeastern coastal plains to temperate further inland. In general, temperature, precipitation, and length of growing season increase to the south. However, a wide variety of local microclimatic conditions exist in the complex topography of the Appalachian mountain region. Seasonal weather patterns are driven by alternating cold/dry continental air masses from Canada and warm/moist air from the Gulf of Mexico. Precipitation is generally distributed uniformly throughout the year, mostly as rain. Snow and ice are common in the winter months in beetleweed's northern range and high-elevation mountainous terrain [14,29]. Mean annual precipitation ranges from 39 to 80 or more inches (990-2,000 mm) in the Great Smoky Mountains [9]. Depending on location, annual snow accumulations range from 8 to 48 inches (200-1,220 mm). Tropical cyclones are possible in summer and fall months. Seasonal variations in temperature increase away from the coast. Mean winter temperatures vary from -18 °F (-28 °C) on high-elevation sites and in the north [9] to 64 °F (18 °C) in beetleweed's southern range. Mean summer temperatures are less variable, ranging from 70 to 72 °F (21-22 °C) [14,29].
Beetleweed occurs in the understory of a variety of plant
communities in the northeastern, Mid-Atlantic, and southern United States. It is most common in oak-pine (Quercus-Pinus
spp.) forests that support an understory of mountain-laurel (Kalmia
latifolia) and/or rosebay (Rhododendron maximum). Both
mountain-laurel and rosebay are strongly associated
with beetleweed throughout beetleweed's distribution [2,43,45,68]. Beetleweed also occurs in oak-pine, hardwood, mixed
conifer-hardwood,
conifer, and shrubland communities.
Beetleweed is a common understory species of oak-hickory
forests in the east-central and southern United States. It most commonly
associates with chestnut oak and scarlet oak (Q. coccinea), respectively [1,59].
Chestnut oak (Quercus prinus) is beetleweed's most frequent overstory dominant
across beetleweed's distribution [1]. In a mixed-oak
forest on the Jefferson National Forest of Virginia, overstory dominants of
beetleweed are chestnut oak, scarlet oak, and red maple (Acer rubrum). Ericaceous shrubs including
black huckleberry (G. baccata) and Blue Ridge blueberry (Vaccinium
pallidum) dominate the shrub layer. American
alumroot (Heuchera americana) is a common forb (review by [59]).
Beetleweed is an important component of the chestnut oak/mountain-laurel community in South
Carolina's Jocassee Gorges. Bear huckleberry (Gaylussacia ursina),
Piedmont rhododendron (Rhododendron
minus), and fairywand (Chamaelirium luteum) are other important species [1].
Besides chestnut and scarlet oak, other oak-hickory forest dominants
sometimes associated with beetleweed include blackjack oak (Quercus marilandica), post oak
(Q. stellata), northern red
oak (Quercus rubra), white oak (Q. alba), black oak (Q. velutina), scarlet oak, southern red oak
(Q. falcata), turkey oak (Q. laevis),
pignut hickory (C. glabra), black hickory (C. texana), and mockernut hickory (C. tomentosa).
Understory tree and shrub associates include flowering dogwood (Cornus florida), blueberries
(Vaccinium spp.),
huckleberries (Gaylussacia spp.), and sumacs (Rhus spp.).
Herbaceous plant associates include bluestems (Andropogon spp.), little bluestem
(Schizachyrium scoparium), and sedges (Carex spp.)
[21,29,31,72].
Beetleweed was important in preblight American chestnut (Castanea dentata) stands. In a stump survey
reconstructing early 20th century American chestnut riparian forests of the Blue
Ridge Mountains, rosebay dominated former American chestnut stands disturbed by
blight and harvest of infected American chestnuts in the 1920s and 1930s. Beetleweed and partridgeberry (Mitchella
repens) were abundant in the rosebay thickets, and other herbaceous species were nearly absent
[68]. Postblight American chestnut forests have mostly succeeded to rosebay
thickets, mountain-laurel thickets, or oak-hickory forest [19,45,68].
Beetleweed is a common herbaceous associate of xeric oak-pine forest. Percent cover of beetleweed ranges from 5% to 20% in this forest type.
Oak-pine forests are common on south-facing
slopes in the central and southern Appalachian, Piedmont,
and Coastal Plain regions. A 1935 publication noted that beetleweed was common in a
shortleaf pine (Pinus echinata)-chestnut oak community on Pine Mountain, Kentucky. Understory
shrubs included black huckleberry, Blue Ridge blueberry, and mountain-laurel. Narrowleaf silkgrass (Pityopsis
graminifolia), downy danthonia (Danthonia sericea), and
partridgeberry (Mitchella repens) were common herbaceous associates [6].
Within oak-pine forests, chestnut oak is the most common overstory associate of
beetleweed; scarlet oak is 2nd. Dominant pines include pitch pine (P. rigida),
Table Mountain pine (P. pungens), and/or Virginia
pine (P. virginiana). In a review, Murphy and Nowacki [46]
noted beetleweed as important in high-elevation, old-growth Table Mountain pine communities
in the Great Smoky Mountains. Pitch pine, scarlet oak, chestnut oak, and
black tupelo (Nyssa sylvatica) were common overstory associates; mountain-laurel and blueberries dominated the understory. With 5% to 20% coverage, beetleweed, trailing arbutus (Epigaea
repens), and eastern teaberry (Gaultheria procumbens)
dominated groundlayer vegetation [46].
Beetleweed is a common understory component of northern hardwood forests.
These forests are generally found at mid- to high elevations in the central and
northern Appalachian Mountains, often transitioning to spruce-fir or mixed
hardwood forest at higher and lower elevations, respectively [45].
Common overstory tree species include sugar maple (Acer saccharum),
basswood (Tilia americana), yellow birch (B. alleghaniensis),
black cherry (Prunus serotina), red spruce (Picea rubens), white spruce (P. glauca),
American beech (Fagus grandifolia), eastern white pine (Pinus strobus),
eastern hemlock (Tsuga canadensis), northern red oak, white oak, and yellow-poplar (Liriodendron
tulipifera). Understory associates include beaked hazel (Corylus
cornuta), eastern leatherwood (Dirca palustris), red elderberry (Sambucus
racemosa var. racemosa), alternate-leaf dogwood (Cornus alternifolia), bush-honeysuckle (Diervilla
lonicera), Canada yew (Taxus canadensis), red raspberry (Rubus idaeus),
and blackberries. Herbaceous species include Carolina springbeauty (Claytonia caroliniana),
snow trillium (Trillium grandiflorum), anemones (Anemone spp.), marsh
blue violet (Viola cucullata), downy yellow violet (V. pubescens),
hairy Solomon's seal (Polygonatum pubescens), starry Solomon's-seal (Maianthemum
stellatum), hairy sweet-cicely
(Osmorhiza claytonii), adderstongues (Ophioglossum spp.), Jack-in-the pulpit (Arisaema
triphyllum), bigleaf aster (Eurybia macrophylla), and
clubmosses (Lycopodiaceae) [45,58,72].
Beetleweed is a groundlayer species in mixed hardwood forests.
These forests often support a high level of plant diversity [29]. Overstory
hardwood and conifer associates of beetleweed are numerous within the type. They include northern red
oak, white oak, black oak, scarlet oak, southern red oak, post oak,
yellow-poplar, eastern white pine, American beech, sugar maple, red maple, black cherry, American basswood, sweetgum (Liquidambar styraciflua),
white ash (Fraxinus americana), green ash (F. pennsylvanica),
quaking aspen (Populus tremuloides), hickories, black tupelo, black walnut (Juglans nigra), jack pine (Pinus
banksiana), eastern hemlock, and elms (Ulmus spp.). Common
mid-canopy tree associates include flowering dogwood,
hollies (Ilex spp.), eastern hophornbeam (Ostrya virginiana),
sassafras (Sassafras albidum), American bladdernut (Staphylea trifolia),
eastern redbud (Cercis canadensis), common persimmon (Diospyros virginiana),
and serviceberries (Amelanchier spp.). Common understory shrubs and vines include greenbriers
(Smilax spp.), blueberries, rosebay,
eastern leatherwood, witch-hazel (Hamamelis virginiana), beaked hazel, spicebush (Lindera benzoin),
poison-ivy (Toxicodendron radicans), and grapes (Vitis spp.) [9,45,58,72].
Beetleweed frequents openings or open stands of spruce-fir (Picea-Abies
spp.) forest in the central and southern Appalachian arboreal
highlands, mountain tops, and "balds"
[9,58]. Southern spruce-fir forests are dominated by red spruce, which mixes
with hardwoods on mid-elevation slopes. Common overstory associates
include Fraser fir (A. fraseri), yellow buckeye (Aesculus flava),
sweet birch (Betula lenta), and black cherry.
Rhododendrons (Rhododendron spp.),
American mountain-ash (Sorbus americana), and possumhaw (Viburnum
nudum var. cassinoides) are common understory dominants. Other
shrub associates include highbush cranberry (V.
edule), mountain holly (I. montana),
speckled alder (Alnus rugosa), pin cherry (Prunus pensylvanica),
serviceberries, raspberries (Rubus spp.), blueberries, and
huckleberries [58].
Beetleweed occurs in the groundlayer of Carolina hemlock (Tsuga caroliniana)
forest. Overstory associates include red maple, chestnut oak, and
sweet birch. Understory vegetation is not diverse in the type [57].
Mountain-laurel and rosebay are common shrubs. Groundlayer vegetation includes
vines such as Virginia creeper (Parthenocissus quinquefolia) and partridgeberry, and forbs including beetleweed,
Virginia heartleaf (Hexastylis virginica),
and Carolina silverbell (Halesia
carolina) [57,58,72].
Beetleweed is occasional on upland and mesic sites within
longleaf pine (P. palustris) forests and savannas in and along the
Atlantic and Gulf coastal plains and lower Piedmont regions of Georgia
and Alabama. Associated species on mesic coastal plains include southern
red oak, blackjack oak, water oak, flowering dogwood, black tupelo, sweetgum,
common persimmon, and sassafras. Associated
species on xeric sandhill sites include turkey oak, bluejack oak (Q. incana), and live
oak (Q. virginiana). Associated shrubs include inkberry (I. glabra), yaupon
(I. vomitoria), large gallberry (I. coriacea), wax-myrtle (Myrica
cerifera), blueberries, huckleberries, blackberries, saw-palmetto (Serenoa
repens), sweetbay (Magnolia virginiana), cyrilla (Cyrilla racemiflora),
and buckwheat tree (Cliftonia monophylla). Pineland threeawn (Aristida stricta) is the primary
groundcover on longleaf pine sites within beetleweed's distribution [14,50,58,72].
Shrub balds
often occupy the highest (>4,000 feet (1,200
m)) mountain peaks in the central and southern Appalachian Mountains. Dense
thickets of usually ericaceous shrubs dominate. Bald dominants and
associates across beetleweed's range include mountain-laurel,
Catawba rosebay (Rhododendron catawbiense),
highbush blueberry (Vaccinium
corymbosum), black chokeberry (Photinia melanocarpa), mountain
sweetpepperbush (Clethra acuminata), mountain holly, possumhaw, blackberries, and American mountain-ash [9,58,72].
In South Carolina, beetleweed is common to codominant on high-elevation
mountain-laurel balds [1]. In North Carolina, it forms a shrub/forb community
with silvery nailwort (Paronychia argyrocoma) on the summit of
King's Pinnacle, just above bear oak-dominated shrubland [4].
The following vegetation typings describe plant communities where beetleweed is a dominant
or important component of the ground layer.
Beetleweed is harvested for use in the floral industry. Its durable, shiny evergreen leaves, which are brightly colored in fall, are highly prized as background foliage in floral arrangements. It is also used for landscaping [51].
Native Americans traditionally used beetleweed for treatment of kidney ailments [41].
Beetleweed establishes after fire [9,23], although documentation of the method (rhizome sprouts and/or seedling establishment) is lacking as of this writing (2006). It is likely that if plants are healthy before fire and there is sufficient rainfall afterwards, top-killed beetleweed rhizomes sprout readily after fire. However, beetleweed's postfire recovery rate varies, and current research (as of 2006) does not explain the variation. Research is needed on beetleweed's fire ecology.
Several studies note beetleweed presence on burns [9,16,22,23]. For example, beetleweed occurred with 1% to 2% frequency and 32% cover in an "old" and a "recent" burn in the Great Smoky Mountains of North Carolina and Tennessee. Time-since-fire was not determined for the old burn; the recent burn occurred "several years" before the 1929 survey [9].
Beetleweed can be slow to establish after fire relative to associated species. To increase the pine component and overall diversity of a mixed pitch pine-scarlet oak-chestnut oak/mountain-laurel forest, broadcast prescribed burning and white pine plantings were done following clearcutting on the Nantahala National Forest of North Carolina. Clearcutting occurred in 1990 and was finished by late July; prescribed burning was conducted about 2 months later on 18 and 19 September 1990. The fire consumed the forest litter and fine woody material. Large woody debris in the burn's interior was "consumed or reduced." Beetleweed's postfire frequency and height were low compared to 27 and 31 other herbs present on 2 study plots. Beetleweed mean biomass, height, and density on 2 study sites are given below. Plots were 0.05 ha (n=5); plots on the 2 sites were measured in successive years [23]:
FrequencyBeetleweed reproduces sexually and asexually. Information pertaining to the reproductive biology of beetleweed is sparse, and the degree to which beetleweed relies on reproduction from seed vs. cloning is unknown.
Breeding system: Beetleweed is monoecious [41]. In a 1992 to 1999 survey, Greller and Clemants [30] noted beetleweed establishment and population expansion by seed spread on Long Island, New York, where beetleweed was previously uncollected and is probably not native.
Polyploidy may give beetleweed greater ecological amplitude than a simple diploid state [9,47]. Although geographic distributions of the 2 races overlap, they apparently do not cross-breed [47].
Seed dispersal: Beetleweed's small, light seed is "easily transported" [9]. Mechanisms for transport are not described in current (2006) literature.
Seed bank: The degree to which beetleweed relies on a seed bank is unknown. In seed bank study conducted in a chestnut oak-scarlet oak forest on the Jefferson National Forest, beetleweed seed was neither visually apparent in soil samples, nor did it germinate from soil samples in the greenhouse. However, beetleweed was a dominant forb in the study area [59]. Methodologies can affect seed bank trials [61], and absence of beetleweed emergence in seed bank studies does not mean that beetleweed does not form a seed bank. Further studies are needed on seed ecology of beetleweed.
Asexual regeneration: Beetleweed reproduces asexually [48] from rhizome sprouts [51,52,55,63].
As of 2006, published literature describing pollination, seed dispersal, seed production, seed banking, germination, seedling establishment, or growth for beetleweed was lacking. Further research is needed on beetleweed's life history.
Beetleweed occurs in early [1,19,36], mid- [20], and late-successional forests [1,13,19,35]. It is shade tolerant [68]. Partial shade provides best light conditions for beetleweed (review by [51]).
Early succession: A study of forest succession in mixed conifer-hardwood riparian forests of the southern Appalachians noted beetleweed's rarely documented importance in early succession. With 69% frequency, beetleweed was the herbaceous dominant in early seral yellow-poplar-red maple-mountain magnolia (Magnolia fraseri) stands on the Thompson River corridor of North Carolina. It was also present but less frequent on 2 other North Carolina sites in late succession: an eastern white pine-white oak forest and an eastern hemlock-white oak forest (22% and 12% frequency, respectively) [1].
Beetleweed occurred relatively soon after extreme disturbances in the Nantahala Mountains of southwestern North Carolina pushed a forest into early succession. On the Wine Spring Creek Watershed of what is now the Coweeta Hydrologic Laboratory, a former American chestnut forest was "heavily" logged from 1912 to 1923. The forest succeeded to mixed oak after chestnut blight infestations in the early 1920s. Further logging and a type conversion followed decades later. A riparian corridor was partially logged in 1941; after that, treatments involved the entire watershed. The watershed was clearcut and pile burned in 1958; planted to sixweeks grass (Vulpia octoflora, a native annual) in 1959; repeatedly treated with 2,4-D from 1960 to 1965 to suppress woody shrubs including beetleweed; fertilized in 1965; treated with atrazine (to kill grass) and paraquat and 2,4-D (to kill shrubs) in 1967; then left undisturbed. Plots (0.02-ha) were sampled in 1995 to determine understory recovery, using adjacent undisturbed plots (70 years since last harvest) as controls. Forbs dominated the disturbed understory in 1995; red maple and shrubs, including beetleweed, dominated the undisturbed understory. Although method of postdisturbance establishment was not part of the study, beetleweed establishment after 1967 was probably from seed because several successive herbicide treatments in the 1960s would have killed most mature plants. Beetleweed distribution on undisturbed and disturbed plots was [19]:
Frequency (%) Density (plants/m²) Relative density Undisturbed 38 0.8 5.1 Disturbed 3 0.1 <0.1Mid-succession: In another Coweeta Hydrologic Laboratory study, Elliott and others [20] found beetleweed recovered gradually after a chestnut oak-scarlet oak-pitch pine stand was clearcut in 1952. Beetleweed was the 2nd most common herbaceous species in the study area before clearcutting, representing 19% of total understory species composition. Forty-one years later, beetleweed showed 3rd greatest percent relative biomass compared to other understory species. Pre- and postharvest measurements were in different units. Beetleweed's relative biomass was [20]:
Postharvest year 25 27 32 41 Relative biomass (%) 0.0 2.2 6.5 14.8In vegetation surveys of reclaimed surface coal mines of southwestern Virginia, beetleweed occurred only on the oldest (>35 years) reclamation sites. The sites were planted with nonnative grasses ands legumes, native black locust (Robinia pseudoacacia), and eastern white pine, which is native to the general region but not to the reclamation sites [39]. Nonnative plantings probably altered the successional trajectory. Without comparative studies, it is difficult to access beetleweed's successional position on coal mine sites.
Some heath balds where beetleweed is common to dominant in the understory are successional to chestnut oak, conifer, or oak-pine forest without fire or other disturbance. Depending upon time-since-fire or other disturbance, the heathlands vary from open to very dense (review by [25]), so degree of beetleweed exposure on balds could vary greatly. Beetleweed's successional role in heath balds is not described in current (2006) literature.
Late succession: Beetleweed presence has been noted in heavily shaded, old-growth mixed- and northern hardwood forests [45,58,72].
