''Asclepias quadrifolia'', commonly called four-leaved milkweed or fourleaf milkweed, is a species of milkweed in the Apocynaceae (dogbane) family. It is sometimes referred to as whorled milkweed, but it should not be confused with '' Asclepias verticillata''. ''A. quadrifolia'' occurs in the eastern United States and Canada.

Description

Fourleaf milkweed is a perennial herb with an upright stem growing from a fleshy

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

. The stem has a milky sap. The plant is small and slender compared to other milkweeds at only tall. Leaves are usually elliptic to ovate and long and wide. Leaves are opposite and appear in 3 to 4 sets on the stem, with one of the higher sets having 4 leaves arranged in a whorl (giving the plant its common name) and the other sets consisting of only 2 leaves. Fourleaf Milkweed Old Pods

Pale pink to white flowers are borne in 1 to 3 rounded, usually pendulous clusters, or umbels from the leaf axils and terminus. The fruit is a follicle or pod that is very slender, long and thick, lacking tubercles, minutely hairy to glabrous. The seeds are broadly oval with a length up to . They are tufted with white to tan hairs at their tips.

Distribution and habitat

''A. quadrifolia'' is native in the United States from Kansas and Oklahoma in the west, to Mississippi and Alabama in the south, and New Hampshire in the north and east. It is an endangered species in Ontario. Unlike more commonly known species such as

common milkweed ''Asclepias syriaca'', commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is native to southern Canada and much of the United States east of the Rocky Moun ...

or butterflyweed, fourleaf milkweed is a woodland denizen. It usually occurs in dry, rocky open forest. It is frequently found on upland slopes.

Ecology

Flowers bloom from May to July. Insects that take

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...

from the plant include bumblebees and other

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s, wasps, ants, flies, and

butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...

. The

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...

s of the

monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. It ...

feed on the foliage.

Conservation

''A. quadrifolia'' was listed as an endangered species in Ontario in 2010. Only 2 populations are known to remain in the province, both in Prince Edward County. The plant is also listed as endangered in New Hampshire and threatened in Rhode Island.

Toxicity

Most ''Asclepias'' are toxic if consumed in large quantities due to cardiac glycoside and

resinoid Resinoids are extracts of resinous plant exudates (balsams, oleo gum resins, and natural oleoresins). Production Resinous plant exudates (balsams, oleo gum resins, and natural oleoresins) and animal secretions (ambergris, castoreum, musk, and civ ...

content.

Cultivation

Fourleaf milkweed is rare in cultivation.

References

External links

University of Texas
{{Taxonbar, from=Q4803913 quadrifolia Flora of North America Flora of Ontario Butterfly food plants