The Lady Slipper newsletter, and now blog, of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. We occasionally feature an article from a past issue. In this article from 2011, KNPS Board Member David Taylor, discusses one of Kentucky’s most widespread milkweed, common milkweed (Asclepias syriaca). This article ran in Vol. 26, No. 3. If you would like to see these and other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, February 1986 to Vol. 39, 2024, can be found.

Kentucky’s Common Milkweed (Asclepias syriaca L.)

By David Taylor, US Forest Service

Common milkweed is a perennial forb that spreads by means of rhizomes and seed. It is one of about 115 species that occur in the Americas. Most species are tropical or arid land species. Plants may occur as a few individuals, but once established, form small to large colonies. Individual plants range from 1 to 2 m (~ 3 to 6 ft) tall. Leaves are elliptic to ovate to oblong and somewhat thick. Mature leaves are 15-20 cm (6-8 in) long and 5 to 9 cm (~ 2 to 3.6 in) wide, with a prominent midvein. The underside of the leaf is frequently finely pubescent. The stem is stout, usually simple, and green to black (see below) in color. When broken, the leaves, as well as stem and fruit, exude milky latex. Flowers are purplish to rosy pink to mostly white or even greenish and about 2 cm (0.75 in) long and 1 cm (0.4 in) wide. They occur in semi-spherical umbels (umbrella-like clusters) in the upper leaf axils. Flowers are somewhat complex in their structure, with structures not found in the average flower (see Cut Flower Exports of Africa – Asclepias). The flowers are strongly and sweetly scented. The fruits (pods), known as follicles, are formed from the union of multiple flowers. They are green, covered in soft spiky projections and are finely pubescent. When the seeds are mature, the follicle splits exposing the seeds. Each seed is equipped with a coma, a soft group of hairs. As the newly exposed seeds dry, the hairs of the coma expand allowing the seed to catch a ride on the wind. When broken, the leaves, as well as stem and fruit, exude milky latex.

The Lady Slipper newsletter, and now blog, of the Kentucky Native Plant Society has been published since the Society’s founding in 1986. We occasionally feature an article from a past issue. In this article from 2004, Alan Weakley, looks at the taxonomic changes in the 1990s that moved American asters out of the Eurasian genus Aster into several American genera . This article ran in Vol. 19, No. 3. If you would like to see these and other past issues, visit the Lady Slipper Archives, where all issues from Vol. 1, February 1986 to Vol. 39, 2024, can be found.

The Curious Case of the Disappearing Asters . . .

by Alan Weakley

Reprinted with permission of the author from the North Carolina Botanical Garden Newsletter 32(2). March-April 2004.

Would an aster by any other name look as showy?

One dark and stormy night in 1994 I was awakened from a deep sleep by a loud thump. Creeping carefully down the stairs, I discovered to my astonishment that a large bouquet of Aster on the dining table had disappeared! In its place was a cornucopia of composites, including Symphyotrichum, lonactis, Eurybia, Sericocarpus, Doellingeria, Ampelaster, and Oclemena! Once again, a plant taxonomist had struck in dark of night, taken a simple two- syllable genus with the same English common name, and replaced it with a handful of four- and five-syllable Latin tongue-twisters. Whatever can we do about such things?

The classification of living things is based on the principle that each taxonomic unit (for instance the Composite or Aster Family, the genus Aster, or a species) groups together things that are most closely related to one another, and that the group should not also contain things which are disparate, unrelated, or more closely related to another group.

The concept of the genus Aster has had a long history of controversy and confusion. Asa Gray, the most influential nineteenth-century North American botanist, struggled with Aster at all levels, from its circumscription (what to include in it), to the taxonomy of the component species. Late in his life, he wrote:

“I am half dead with Aster. I got on very fairly until I got to the thick of the genus, around what I call the Dumosi and Salicifolia. Here I work and work, but make no headway at all. I can’t tell what are species and [sic] how to define any of them …. I was never so boggled …If you hear of my breaking down utterly, and being sent to an asylum, you may lay it to Aster, which is a slow and fatal poison.”