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: “Water-shield”, Brasenia schreberi]
Frequently the leaves and stems of a plant will prove to be just as fascinating as its flowers. This is a plant like that, and it is a native, aquatic species.
Except for its leaves, the entire plant grows below the surface of water, most often in quiet lakes and millponds, or sometimes creeks or beaver ponds. In the Southeast, it is most commonly seen in ponds on the coastal plain and in the sandhills, but it also grows in the mountain lakes. It’s often easy to see in the various impoundments in a number of state parks, and of course, it is unmistakable for anything else. This species is actually quite common in many places around the world now. You generally need to do some wading to get up-close and personal with it, unless you have a canoe or kayak.
The leaf blades, dark green or sometimes purplish, are shaped like little footballs with rounded ends. Each blade is attached to a very long leaf stalk at its center, rather than at its edge, and botanists say that the leaf is thus “peltate”, in architecture something like an umbrella with its handle. What is more interesting is that the lower surfaces of the leaves, and for that matter, all the submersed parts of the plant, are thickly coated with a crystal-clear, mucilaginous jelly. Because of this, it is something of a challenge to handle the plants: they are really quite slippery. This mucilage on the stems and leaves may serve some purpose, but we don’t exactly understand what it might be. Seems like a good research project for an imaginative botany student. (It’s also hard to make a decent herbarium specimen of this plant, as the mucilage tends to adhere tightly to the paper in which it is being pressed. But botanists love a challenge.)
The flowers are not much more than the size of a quarter, deep red or maroon, and barely emerging from the water’s surface. The flowers appear in the middle of the summer. To many people, this plant looks to be some sort of water-lily, and in fact they are somewhat related, although water lilies (the genus Nymphaea) have much showier flowers, and the leaves are not peltate. Now, in our Mystery Plant, each flower is “perfect”…in having both female and male parts (that is, pistils and stamens). But the flowers behave as though they “imperfect”, or unisexual. How? It turns out that a given individual flower will open up and have its pistils fertilized, without giving off any pollen…thus functioning as a “female” flower. That same day (or evening), the plant will pull the flower under the water. The next day, the SAME flower reemerges from the surface, only this time, sheds pollen from its stamens (now, functioning as a “male” flower). At the end of the second day, the flower disappears underwater, never to be seen again, allowing its seeds to develop, eventually released.
What a strange and wonderful pair of botanical stories!
(Photo by Linda Lee.)