John Nelson is the curator of the A. C. Moore Herbarium at the University of South Carolina, in the Department of Biological Sciences, Columbia SC 29208. As a public service, the Herbarium offers free plant identifications. For more information, visit www.herbarium.org or call 803-777-8196, or email email@example.com.
[Answer: “Lopsided Indian-grass,” Sorghastrum secundum
I hope you will remember from your introductory Economic Botany class that the grasses, as a family (called the Poaceae), surely represent the most important plants in the world, as far as human economy goes. Practically every human culture has developed around the growing and consumption of at least one grass species. Beyond human economy, the grasses are of paramount importance in many ecological systems. It’s an enormous family, with many thousands of species. Some grasses have something of a dark side, and can be aggressive invaders; unfortunately we have plenty of them here in the Southeast. For the beginning botanist, identifying grasses to species level can really be a bewildering experience, and it takes considerable practice to become familiar with the various groups within the family. We’ll save the discussion of detailed characteristics for another time, but remember that grass stems are usually round (and hollow) and their flowers are crowded into what we call spikelets. And, the fruit of a grass is what we call a grain, which always contains a single seed.
There is a popular grass species that is commonly cultivated here in the Southeast, and everybody has seen it. It’s called “Pampas-grass,” and it’s native to South America. It forms large, spreading clumps, and usually stays where it is supposed to. Other introduced species of large, plume-forming grasses are much more aggressive, including the dreadful common reed (Phragmites australis), giant cane (Arundo donax), and zebra grass (Miscanthus sinensis), all of which now represent serious problems on our landscapes as invasive species. (There are also a number of other “fuzzy-topped” grass species, both native and introduced: perhaps you’ve heard of “Cogon grass”, which is one of our most serious invaders.)
We also have a number of native grasses which form prominent plume-like inflorescences. Most of these are perennials, and form clumps. Of our native plume-forming grasses, some of the showiest species reside in the group that we call the “Indian grasses,” and one of these species is featured as this week’s mystery plant.
A couple of Indian grass species are quite common throughout the Southeast, and they are rather easy to see in a variety of habitats. Our mystery plant, however, is a true lover of the Deep South, found only on the coastal plain, from the low-country of South Carolina to Florida and over to Louisiana. It occurs on dry ground, and may be found in some abundance in ecosystems which experience periodic fire. It forms thin clumps, with the stalks rising sometimes as high as six feet, then with a prominent plume of bright, shiny brown and gold, hairy spikelets. In this species, the spikelets are somewhat clustered together on one side of each branchlet. While in bloom (which is now), the tiny, yellow anthers may be seen dangling from each spikelet on a thread-like stalk. This species is attractive enough that it is now accessible in the gardening trade. It can be grown in most sandy soils, and tolerates drought well. (Photo by Linda Lee.)