MYSTERY PLANT: Spectacular autumn color found in grass
In the other gardens
And all up the vale,
From the autumn bonfires
See the smoke trail!
—Robert Louis Stevenson,
A cloud, a haze, a rolling blanket of misty pink, softening the ditches, the ruts, the flatwoods: you’ll see it quieting a craggy landscape, forming a dreamy, filmy fog with the autumn-blooming asters, gerardias, and goldenrods. And all those other wonderful fall wildflowers, too.
Here is a native grass that surprises us with its sudden and spectacular burst of impressive color in the early autumn. The bottoms of the plants, leafy and green, have been waiting for this show all summer, as if we viewers have forgotten the spectacle from last year. Suddenly the plant “goes to seed”, each individual plant producing a massive panicle over a very few days. (The panicle, of course, is a kind of inflorescence, just an architectural arrangement of the flowers. In a panicle, the flowers are on a much branched stalk…something of a “panic”…you might think of it that way.) The branches of the panicle are what give the wonderful color, as the branches, some as thin and delicate as a strand of hair, are red or pink. The effect, of course, when the panicle is fully expanded, is one of a pink shroud hovering over the ground. As autumn becomes winter, the colorful panicles will fade, but will still retain a kind of late-season, transparent beauty.
The flowers of grasses, of course, are always sequestered within small little packages called “spikelets”. Depending on the grass species, each spikelet will contain one or more very tiny flowers. There are no petals at all. It is really amazing to study the ways in which grasses have developed such a myriad of patterns of inflorescences and spikelets. Our mystery plant has spikelets that are quite small and slender, scarcely more than a third of an inch long, and featuring a short little bristle. There will only be one flower inside the spikelet, and this flower will eventually produce a very tiny little grain, loosely held in the bracts of the spikelet until it falls away.
Our mysterious grass is actually rather common. It grows in a variety of habitats, mostly on the dry side, throughout all the Southeastern states. The plants seen in this image came from a patch growing at the edge of a pine savanna here in South Carolina, in the Francis Marion National Forest. Some very popular garden varieties have been developed, too, which to me is a very good idea. (I’d love to have some.)
(It’s interesting that the rather uncommon “sweet grass”, which is used by the Gullah people to fashion their baskets, is a very closely related species, one that is also native, but restricted to sandy places right along the Atlantic coast, and on barrier islands, and down to northern Florida. For more on these two grass species, consider Bruce Sorrie’s excellent “Wildflowers of the Sandhills Region”, published 2011, by the UNC Press.)
John Nelson is the curator of the A.C. Moore Herbarium in the Department of Biological Sciences at USC. As a public service, the herbarium offers free plant identifications. For more information, visit www.herbarium.org or call (803) 777-8196.