乳草

馬利筋屬
	Asclepias syriaca
科學分類
界：	植物界 Plantae
演化支：	維管束植物 Tracheophyta
演化支：	被子植物 Angiosperms
演化支：	真雙子葉植物 Eudicots
演化支：	菊類植物 Asterids
目：	龍膽目 Gentianales
科：	夾竹桃科 Apocynaceae
屬：	馬利筋屬 Asclepias
種：	馬利筋屬 Asclepias
二名法
	Asclepias; Linn.

馬利筋屬下的植物通稱乳草，又稱乳仔草、紅乳草、細本乳仔草、千根草、乳汁草-嶺南、痢疾草-廣東、細葉飛揚草-廣州、萹蓄草-台灣，是多年生草本植物的一屬，屬於夾竹桃科植物，涵括超過140種植物。例子有馬利筋。

馬利筋物種已經演化出精巧的抵禦策略以對抗吃它們葉子的毛蟲。這些包括葉子上的毛、其組織中稱為心臟干擾素的心臟毒以及來自於植物管狀器官的乳白色有毒乳汁，故馬利筋又稱乳草。

部分種編輯

	Asclepias albicans	Whitestem milkweed, native to the Mojave and Sonoran deserts
	Asclepias amplexicaulis	Blunt-leaved milkweed, native to central and eastern United States
	Asclepias asperula	Antelope horns, native to American southwest and northern Mexico
	Asclepias californica	California milkweed, native to central and southern California
	Asclepias cordifolia	Heart-leaf milkweed, native to the Sierra Nevada and Cascade Range up to 2000 m.
	Asclepias cryptoceras	Pallid milkweed, native to the western United States.
	Asclepias curassavica	Scarlet milkweed, tropical milkweed, bloodflower, bastard ipecacuanha, native to the American tropics, introduced to other continents
	Asclepias curtissii	Curtiss's milkweed, endemic to sandy areas of Florida
	Asclepias eriocarpa	Woollypod milkweed, native to California, Baja California, and Nevada
	Asclepias erosa	Desert milkweed, native to California, Arizona, and Baja California
	Asclepias exaltata	Poke milkweed, native to eastern North America
	Asclepias fascicularis	Narrow-leaf milkweed, native to Western United States
	Asclepias hirtella	Tall green milkweed
	Asclepias humistrata	Sandhill milkweed, native to southeastern United States
	Asclepias incarnata	Swamp milkweed, native to wetlands of North America
	Asclepias involucrata
	Asclepias lanceolata	Lanceolate milkweed (Cedar Hill milkweed), native to coastal plain of eastern United States from Texas to New Jersey
	Asclepias linaria	Pine needle milkweed, native to Mojave and Sonoran deserts
	Asclepias linearis	Slim milkweed
	Asclepias meadii	Mead's milkweed, native to midwestern United States
	Asclepias nivea
	Asclepias nyctaginifolia	Mojave milkweed, native to the American southwest
	Asclepias obovata	Pineland milkweed
	Asclepias purpurascens	Purple milkweed, native to eastern, southern, and midwestern United States
	Asclepias quadrifolia	Four-leaved milkweed, native to eastern United States and Canada
	Asclepias rubra	Red milkweed
	Asclepias solanoana	Serpentine milkweed, native to northern California
	Asclepias speciosa	Showy milkweed, native to western United States and Canada
	Asclepias subulata	Rush milkweed, leafless milkweed, native to southwestern North America
	Asclepias subverticillata	Horsetail milkweed^[1]
	Asclepias sullivantii	Sullivant's milkweed
	Asclepias syriaca	Common milkweed
	Asclepias texana	Texas milkweed
	Asclepias tuberosa	Butterfly weed, pleurisy root
	Asclepias uncialis	Wheel milkweed
	Asclepias variegata	White milkweed
	Asclepias verticillata	Whorled milkweed
	Asclepias vestita	Woolly milkweed
	Asclepias viridiflora	Green milkweed
	Asclepias viridis	Green antelopehorn, spider milkweed
	Asclepias welshii	Welsh's milkweed