pierre laszlo

Asclepias californica, aka milweed

Its healing virtues made Linnaeus name it Asclepias, after the Greek God of medi-cine. The genus Asclepias, part of the family of Apocynaceae, to which the periwinkle also belongs, comprises 140 species.

An herbaceous, dicotyledoneous perennial, it is found in meadows, fields, open woods, waste areas, roadsides. Many features are remarkable. The thick, white, woolly stems which bend or run along the ground, can grow up to 2 or 3 ft. The thick, broad-oblong, reddish-veined, light green leaves are up to 8 in-long. The abundant, rounded, hanging flowers, pink, mauve, white, with reflexed corollas and starlike arrays of bulbous anthers bloom from late spring well into summer. The seeds encased in large follicles and arranged in overlapping rows, carry white silky filament-like hairs, reminiscent of those on dandelion seeds and known as trichomes. The follicles dry and split open and the seeds, each hoisted by several delicate filaments, scatter in the wind.

True to their name, Asclepias plants amount to medicine chests. Cut or bruised stems and leaves exude a milky latex. As a folk remedy, it was used to remove warts. It was un-successfully studied as a source of natural rubber by both Germany and the United States during World War II. It served as candy to Kawaiisu native Californians, the latex within the leaves is sweet-flavored (sucrose) and chewy upon cooking. The raw plant though is very toxic, due to chemicals known as cardiac glycosides, also known as cardenolides which interfere with the proper balance of sodium and potassium  within animal cells. Ac-cordingly, South American and African tribes used arrows laced with these glycosides to fight and hunt more effectively. Cardenolides may cause death when herbivores consume 10% of their body weight in any part of Asclepias. Ecologists at Cornell have reported an evolutionary decline in the three most potent resistance traits against herbivores (cardeno-lides, latex, and trichomes) and an escalation in regrowth ability.

Notesworthy is the habitat Asclepias californica provides to caterpillars of the Monarch butterfly. They encocoon on the underside of the leaves, which they feed on: the bitter and toxic akaloids they ingest from the plant are retained in the adult butterfly, making it un-palatable to predators. In other words, butterflies are smarter than cows, which one may have suspected already.