poison milkweed(n = noun.plant) asclepias subverticillata, horsetail milkweed - milkweed of southwestern United States and Mexico; poisonous to livestock;
is a kind of milkweed, silkweed

bushman's poison, eastern poison oak, fly poison, horsetail milkweed, marsh milkweed, mead's milkweed, milkweed, milkweed butterfly, milkweed family, orange milkweed, poison, poison arrow plant, poison ash, poison bush, poison camas, poison cup, poison dogwood, poison gas, poison hemlock, poison ivy, poison mercury, poison oak, poison parsley, poison pea, poison pill, poison sumac, poke milkweed, showy milkweed, south american poison toad, swamp milkweed, western poison oak, white milkweed, whorled milkweed