Showy Milkweed

Asclepidaceae speciosa

Butterfly on Milkweed

Showy milkweed is a member of the milkweed family (Asclepidaceae). The name "milkweed" refers to the milky, white sap that is present in most members of this family, and the habit of growing in poor or "weedy" soil. Many milkweeds grow in the pantropical areas, especially South America, with only nine genera growing in the temperate regions of the northern and southern hemispheres.

The genus name Asclepias is for Askelpios, a physician in ancient Greece who professed that he could bring the dead back to life (some myths call him the god of medicine). The Olympic god Hades, fearing a loss of employment, had his brother Zeus zap Askelpios with a thunderbolt after Askelpios brought the great hunter Orion back from the dead.

MilkweedLater Askelpios was placed into the sky as a constellation, the Serpent Holder, for all the good work he had done. (The same honor was accorded Orion.) Askelpios used a symbol of one or two serpents entwined about a staff for his profession; he holds a serpent in his hands in the constellation. That symbol, the caduceus, is still the symbol for the medical profession today. Milkweed was used medicinally in the past.

Speciosa means "species," which refers to this plant being the typical or common species of the genus Asclepias.

Milkweeds have unusually shaped flowers. The flowers are arranged in a 5-pointed star pattern and are symmetrical in shape (you can divide them into equal halves). The sepals are either distinct or joined at the base. From the center of the flower arises a stout column that contains the female portions of the flower -- the style and stigma.

Arising from the base of this column are horn or sac-shaped hoods, called the corona hoods, that house the male portion of the flower -- the anthers. From each anther, pollen grains are produced in small sacs, called pollinium, that are united in pairs and resemble a set of saddlebags.

The stems and undersides of the leaves may be covered in dense white hairs.


When pollinators visit the flowers, their legs slip off of the stout column and fall into slits where the pollen sacs are located. The hairs or projections on the insects' legs catch these pollen sacs, and as the insect pulls its leg free of the slit, the pollen sacs are removed. As the pollinator visits another plant of the same species, the pollen sacs break off on the column, and the pollen grains grow down the style and fertilize the flower's ovary. If the insect cannot pull its leg free, due to the added weight of the pollen sacs, it may become trapped and perish on the flower.



Showy milkweeds are found from Manitoba to Minnesota, south to Texas and westward to British Columbia and California.


Found in weedy locations along roadsides, cultivated fields and irrigation ditches, as well as riparian and wetland sites up to about 7,000 feet.


Showy milkweeds have a stout stem and grow 3 to ­6 feet tall. The stem and undersides of the leaves may be covered with dense white hairs. Leaves are opposite and oval in shape, 1-6" across and 2-8" long.

Flowers are borne in rounded clusters that hang from short, stout stalks. The flowers are over 1" wide and have 5 rose-purple petals and 5 pinkish cream, needlelike, pouch-shaped hoods. The seed pods are 3-5" long and are either spiny or smooth. The pods ripen in the summer and the flat seeds have long silky hairs attached to one end.


Monarch butterflies lay their eggs on the undersides of showy milkweed and some other milkweed plants. The larvae consume the foliage, which is toxic, to make themselves and the adult butterfly stage less palatable to predators. Viceroy butterflies have a very similar appearance to the monarch butterfly. The viceroy relies upon this mimicry to protect itself from predators that mistake these butterflies for the unpleasant-tasting monarchs.

Though some species of milkweed are very toxic (spider milkweed or whorled milkweed), others were used for medical purposes. Butterfly-weed or pleurisy-root (Asclepias tuberosa) was, and still is used today, in teas to treat lung ailments. The sap of showy milkweed was used to treat skin ailments, such as warts, ringworms and poison ivy.

During World War II, the silky down attached to the seeds of milkweeds was used to stuff pillows, life jackets and flight suits. The down is 5 to 6 times more buoyant than cork.

-- Text and Photos by Damian Fagan

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