A milkweed of open areas on serpentine, calcareous, sandstone, or diabase bedrock, or sometimes in open sandy soil. These areas include recently burned slopes on serpentine rock, serpentine grasslands, mowed golf course rough atop serpentine bedrock, open maritime grassland habitats on sandy soil, open limestone slopes within cedar glades, open rocky summit grasslands on diabase rock formations, open calcareous rocky summits, alkaline sandstone ridges within open cedar glades, old pastures with alkaline soils, open cedar glades with exposed sandstone, and dry shaley slopes (New York Natural Heritage Program 2004). Dry fields and dry rocky slopes, including serpentine and limestone (Rhoads and Block 2000). Dunes and other dry sandy sites including prairies, borders of oak woods, road cuts, and railroads (Voss 1996). Dry upland woods, prairies, and barrens, especially in sandy soil (Gleason and Cronquist 1991). Dry woods and openings (Fernald 1970).

Calcareous red cedar barrens A small-patch calcareous rocky summit community occurring on dry, south-facing to southwest-facing slopes and low summits. These sites are characterized by stunted, sparse woodlands with small grassland openings. Hempstead Plains grassland* A tall grassland community that occurs on rolling outwash plains in west-central Long Island. This community occurs inland, beyond the influence of offshore winds and salt spray. * probable association but not confirmed Maritime grassland* A grassland community that occurs on rolling outwash plains of the glaciated portion of the Atlantic coastal plain, near the ocean and within the influence of offshore winds and salt spray. * probable association but not confirmed Red cedar rocky summit* A community that occurs on warm, dry, rocky ridgetops and summits where the bedrock is calcareous (such as limestone or dolomite, but also marble, amphibolite, and calcsilicate rock), and the soils are more or less calcareous. The vegetation may be sparse or patchy, with numerous lichen covered rock outcrops. * probable association but not confirmed

Rocky summit grassland A grassland community that occurs on rocky summits and exposed rocky slopes of hills. Woody plants are sparse and may be scattered near the margin of the community. Small trees and shrubs may be present at low percent cover. Serpentine barrens A grass-savanna community that occurs on shallow soils over outcrops of serpentine bedrock. In New York this community is known only from Staten Island, where the remnants are relatively disturbed. Successional old field* A meadow dominated by forbs and grasses that occurs on sites that have been cleared and plowed (for farming or development), and then abandoned or only occasionally mowed. * probable association but not confirmed

Broom-sedge (Andropogon virginicus) Sweet Vernal Grass (Anthoxanthum odoratum) Purple Needlegrass (Aristida purpurascens) Butterfly Milkweed (Asclepias tuberosa) Side-oats Grama (Bouteloua curtipendula) Fescue Sedge (Carex brevior) Carolina Whitlow-grass (Draba reptans) Red Cedar (Juniperus virginiana) (Liatris borealis)

Grooved Yellow Flax (Linum sulcatum) Switchgrass (Panicum virgatum) Wild Black Cherry (Prunus serotina) Winged Sumac (Rhus copallinum) Little Bluestem (Schizachyrium scoparium) Field Goldenrod (Solidago nemoralis) Yellow Indiangrass (Sorghastrum nutans) Eastern Poison Ivy (Toxicodendron radicans)