There are many Asclepias, or milkweed, species. Milkweeds have a history of medicinal uses and are also eaten. Depending on the species, milkweeds also contain varying amounts of alkaloids that are toxic to humans and livestock. In general, the narrower-leafed milkweeds are the most toxic. Mexican whorled milkweed, with its very narrow leaves, is considered one of the most toxic species in the genus. This is one milkweed that should not be ingested.
Native to Western America Asclepias fascicularis is still found predominantly in the West. Mexican whorled milkweed was thought to have been first known in Mexico, thus the common name. Another folk name is narrowleaf milkweed.
An erect perennial that grows two to four feet in height, Mexican whorled milkweed spreads by creeping underground roots. An aggressive spreader, in some areas it is considered a noxious weed. The linear to lance-shaped leaves have a short petiole (stalk) and form whorls of three to six leaves around the stem. The leaves fold upward along the midrib. The fruit is an erect, smooth, narrow, sharply pointed follicle two to four inches in length. The seeds are about 1/4 inch long and have tufts which aid in air dispersal. The plant has a sticky, milky white sap. Next spring when they are in bloom, I will share pictures of Mexican whorled milkweed flowers. The flowers are umbels (types of flower clusters) and are white to greenish or even tinged with purple.
These mature Mexican whorled milkweed plants were growing near Eagle Lake (Lassen County CA).