Credit: John Nelson
You could call this the "spiny, green, ping-pong ball plant" if you wanted, and why not?
It’s actually a very common perennial aquatic species found throughout most of eastern North America (though absent in southern Florida), often forming stands along pond and stream edges and spring runs. Clumps, which may be thick, emerge from slender rhizomes. Its leaves are typically long and bright green. When growing in deep water or during times of heavy stream flows, the leaves become slender and ribbon-like, swaying gracefully in the current.
The plant blooms in the spring and summer, when a flowering stalk emerges from the clump. These stalks, somewhat zigzagged, may reach 2 to 3 feet tall at maturity. The flowers are quite small and essentially inconspicuous, but they are arranged in compact heads, or globes, or "balls," at different points along the stalk. Female flowers form the lowest heads, sometimes up to five or six in sequence. Several dozen flowers crowd each head. Each flower is dark green and bears a number of small, curious bracts—not exactly petals—at its apex. An elongated pistil emerges from each flower’s ovary, and as the ovaries mature, the pistil bases harden and become spine-like. The overall effect is a dense, round head that appears somewhat prickly. The male flowers, even smaller than the female flowers, are also compacted into heads, which are smaller than the female heads. These are strung out on the stalk above the female heads below. (If you use your imagination, you might find a bit of similarity between this species and the common cattail. In fact, botanists place both in the same plant family.)
In early autumn, the female heads ripen and eventually shatter during the winter, releasing mature, one-seeded fruits (still with the spine-like attachment). Waterfowl enjoy eating these fruits, and humans have also used them as a type of wild grain and even as a coffee substitute. The plants are quite charming and make great additions to a pool or bog garden.
However, there’s a little problem.
In the Southeast, this mystery plant is a true native species and would be great for home gardening. But recently, a very similar species—exotic and weedy—has been sold on the market. If you’re interested in buying these plants at a gardening center, make sure you’re not purchasing the species called Sparganium erectum (oops, I’m giving away part of the answer now!). It’s hard to tell these two species apart, so you might want to consult with the friendly botanists at your local herbarium. In any case, never discard aquatic plants you’ve been growing into a nearby creek or pond—the potential for spreading invasive species is too high.
John Nelson is the retired curator of the Herbarium at the University of South Carolina. As a public service, the Herbarium offers free plant identifications. For more information, call 803-777-8175 or email johnbnelson@sc.rr.com.
[Answer: "American bur-reed," Sparganium americanum]
