Habitat
Natural habitats occupied by D. exaltatum include rich woods (and edges of woods), rocky slopes, semi-open woodlands, glades and prairie openings. The species is tolerant of a limited amount of disturbance and is also periodically found along disturbed road cuts, roadside ditches, old fields, powerline corridors and wooded fence rows. The substrate of occupied habitat is typically dry and rocky, consisting of limestone or other calcareous rock. The species occurs on a variety of slope exposures (south-, southwest-, west-, north-and northwest-facing). Exposures may be steep, receiving full sun or partial shade (Nelson pers. comm. 1993, Pennsylvania Natural Diversity Inventory-West 1993, Wiegman pers. comm. 1993, Cusick pers. comm. 1992, Kunsman pers. comm. 1992, Ludwig 1992, Ludwig 1993, Maryland Natural Heritage Program 1992, Ohio Natural Heritage Program 1992, Rock pers. comm. 1992, Tennessee Department of Environment and Conservation 1992, Tennessee Valley Authority Regional Heritage Program 1992, Isaac 1991a, Roedner et al. 1978, Holt et al. 1974, Steyermark 1963, Small 1933).
The habitat in Maryland consists of xeric, calcareous, semi-open deciduous woodlands and steep, dry limestone woods (Maryland Natural Heritage Program 1992). Populations have been located at elevations ranging from 129-390 m. Associated species include Eupatorium sessilifolium, Lithospermum spp., Ptelea spp., Rhus typhina and Silphium trifoliatum (Maryland Natural Heritage Program 1992b).
Habitat in Missouri consists of rich, steep, north- or west-facing slopes; dry, wooded slopes with small glade openings; dry woods with open canopy; wooded slopes over limestone or cherty limestone; oak woods with gasconade dolomite rock outcrop; rocky soil; limestone outcrops with chert; eroded slopes; dolomite bluffs; canopied forest of young trees with saplings and thickets; the bases of talus slopes at a stream's edge and low woods along creeks. Populations are located at elevations ranging from 210-324 m. Associated species include Cypripedium calceolus var. parviflorum, Juniperus virginiana, Quercus spp. and Waldsteinia fragarioides (Missouri Natural Heritage Inventory 1992, Smith 1992, Ladd 1993, Roedner et al. 1978, Holt et al. 1974, Steyermark 1963). Associated plant species reported from a west-facing slope included Agrimonia rostellata, Liatris squarosa, Polygala senega var. latifolia and Silphium gatesii. Associates at a north-facing slope included Asclepias quadrifolia, Dirca palustris, Gerardia flava var. macrantha, Panicum boscii, Solidago arguta, Trillium recurvatum, Veronicastrum virginicum f. villosum and Viburnum rafinesquianum var. affine (Steyermark 1963). Annual monitoring in Missouri by the National Park Service shows a positive response to prescribed burning. Populations are actively monitored in three prescribed burn units at Ozark National Scenic Riverways, Missouri. Eight plots are monitored in the prescribed burn units, and one control plot outside of the burn units is monitored. Data collected since 2010 show a 270% increase from pre-burn data in the managed plots, and a 41% decrease in the control plot (2022) (M. Briggler, pers. comm., 2023, Ozark National Scenic Riverways, Fire Ecology Program n.d.).
Four extant occurrences of D. exaltatum occur in North Carolina (North Carolina Natural Heritage Program 1993, Weakley pers. comm. 1993). Two occurrences are located in the Blue Ridge Mountains. One occupies a grassy bald over amphibolite rock at about 1500 m in elevation. Associated plant species at this site include Agrostis perennans, Dactylis glomerata, Danthonia compressa, Houstonia serpyllifolia, Lilium philadelphicum, Lysimachia ciliaris, Phleum pratense, Poa sp., Potentilla canadensis, P. tridentata, Prunella vulgaris, Senecio schwienitzianus, Solidago sp. and Trifolium spp.. The second occurrence in the Blue Ridge is found along a maintained roadside at about 1050 m. It occurs over amphibolite rock with the following associates: Arisaema sp., Aster chlorolepis, Betula lenta, Euphorbia purpurea, Isotria medeoloides, Panax quinquefolium, Quercus rubra, Robinia pseudoacacia and Tovara sp.. The remaining two sites occur in the Piedmont along powerline and sewerline right-of-ways at elevations of about 90-150 m. These sites are found over diabase rock, in formerly fire-maintained communities. Associated plant species include Cercis canadensis, Cirsium virginianum, Echinacea laevigata, Rhus aromatica and Viburnum rafinesquianum. Elevations of both extant and historic populations range from 90 to 1928 m (North Carolina Natural Heritage Program 1993, Weakley pers. comm. 1993).
In Ohio, this species is found on limestone or calcareous soil and on slopes (southwest-, east-, north-facing) which are often steep and above streams. Populations are found on open sites or in partial shade. Plants have been found in a variety of habitats, including woods (under mesic secondary growth hardwood and northern white cedar), woodland edges (including oak-juniper), old fields, powerline corridors, prairie openings and their edges, road cuts (often disturbed), roadside ditches, thickets and wooded fence rows. Associated plant species include Amelanchier spp., Andropogon spp., Cornus spp., Juniperus virginiana, Quercus sp., Thuja occidentalis, various prairie species and a number of disturbance-loving herbaceous species (Cusick 1992, Ohio Natural Heritage Program 1992).
The habitat in Pennsylvania consists of dry, well-drained, rocky limestone or calcareous slopes on south to southwest-facing slopes, usually in full sun or partial light (Pennsylvania Natural Diversity Inventory - West 1993, Wiegman pers. comm. 1993, Kunsman pers. comm. 1992, Isaac 1991a). Associated plant species at one location on a steep, southwest-facing landslide scar and associated ridge thicket include Calystegia spithamea, Hybanthus concolor, Staphylea trifolia, Taenidia integerrima and Triosteum angustifolium (Pennsylvania Natural Diversity Inventory - West 1993).
In Tennessee, habitat consists primarily of Ridge and Valley cedar barrens on thin cherty loam over limestone (dolomite). Other occupied sites include oak-cedar woods, mixed pine-cedar woodlands and disturbed areas (e.g., roadsides and pastures), mimicking barrens habitat. The elevation range of known locations is from 207-300 m. Associated plant species include Solidago ptarmicoides, Liatris cylindracea and Tomanthera auriculata. Other associates include Andropogon spp., Lespedeza cuneata, Aster laevis, A. pilosus, Helianthus hirsutus, H. occidentalis, Kuhnia eupatorioides, Solidago rigida, Penstemon laevigatus, Scutellaria incana, Isanthus brachiatus, Lithospermum canescens, Silphium terebinthinaceum, Echinacea purpurea, Hexalectris spicata, Pinus spp., Quercus spp. and Schizachyrium scoparium (Pyne pers. comm. 1994, Pyne 1992, Tennessee Department of Environment and Conservation 1992, Tennessee Valley Authority Regional Heritage Program 1992). Juniperus virginiana is an active invader of this community type.
In Virginia, D. exaltatum occurs almost exclusively on dry calcareous (dolomite or limestone) soils, particularly around openings or in thin woodlands and open glades (Ludwig pers. comm. 1993, Ludwig 1992). It is also infrequently found on greenstone (a basalt with a pH of 6-7) within the state (Ludwig pers. comm. 1993). Kral (1976) found the species sporadically occurring in mixed-mesophytic forested ravines that cut into shales and limestone.