Broad-leafed Milkweed, Common Milkweed

Asclepias latifolia


Description

More than 30 species of milkweeds have been recorded in Texas. Broad-leafed milkweed is noted for its robust nature and leaf size. A perennial, this plant has stout simple stems and four or more pairs of large thick leaves no more than twice as long as they are wide.

The flowers are greenish to white, giving rise to two to four smooth pods about 2 to 3 inches long from July to October.


Habitat

Broad-leafed milkweed is most common along trails and roadsides, less so in pastures. As with many weeds of low palatability, this species increases in heavily grazed pastures. It is frequent to abundant over much of the Trans-Pecos, the Plains and the central and western Edwards Plateau of Texas. It is found from Nebraska to Utah and west to Arizona.


Toxic Agent

This plant poisons cattle and goats, but more often sheep. The toxic agents are cardiac glycosides.

To be poisoned, cattle can eat as little as 1.0 percent of their body weight in broad-leafed milkweed; amounts as low as 0.15 percent have poisoned sheep and goats. Broad-leafed milkweed is toxic in all growth stages, but is most toxic when immature. Cattle can generally graze frost-killed plants and not be poisoned.


Signs of Livestock Ingestion

The signs produced by most species of Asclepias differ only in degree.

They include: First, profound depression, weakness and staggering; Collapse, followed by frequent, intermittent muscular tremors; Labored respiration, elevated temperature and pupil dilation; Death, after a comatose period of variable duration.

Signs appear within a few hours of ingestion of a toxic dose, and death follows within a few days in most fatal cases.


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