Asclepias quadrifolia is a species of milkweed commonly called fourleaf milkweed or whorled milkweed. The plant occurs in the eastern United States and Canada.
Fourleaf milkweed is a perennial herb from a fleshy rhizome. The plant is small and slender compared to other milkweeds at only 45 cm tall. Leaves usually elliptic to ovate, opposite in arrangement but clustered to form a false whorl, 2.5-12.0 cm long, 1–6 cm wide. Pale pink to white flowers are borne in rounded, usually pendulous clusters from the leaf axils and terminus. The fruit is a follicle or pod which is very slender, 3.2 to 5.6 inches long, 1/4 to 1/3 thick, lacking tubercles, minutely-hairy to glabrous; seeds broadly oval, to 1/3 inch long, tufted with white to tan hairs at tips.
Unlike more commonly-known species such as common milkweed or butterflyweed, fourleaf milkweed is a woodland denizen. It usually occurs in dry, rocky open forest. It is frequently found on upland slopes.
Fourleaf milkweed is rare in cultivation.
- http://www.missouriplants.com/Pinkopp/Asclepias_quadrifolia_page.html Missouri Plants
- http://www.monarchwatch.org/milkweed/guide/quad.htm Monarch Watch Milkweed photo guide
- http://www.kswildflower.org/flower_details.php?flowerID=367 [Kansas Wildflowers]
- http://mdc.mo.gov/discover-nature/field-guide/whorled-milkweed-fourleaf-milkweed [Missouri Department of Conservation]
- http://www.wildflower.org/plants/result.php?id_plant=ASQU Lady Bird Johnson Wildflower Center
- http://davesgarden.com/guides/pf/go/73613/#b Dave's Garden Listing