On Saturday morning, September 3, 2016, as Hurricane Hermine pounded Virginia’s coast, 25 FODMers studied the plants of Dyke Marsh on a windy, “rainless,” three-hour walk. “At least there’ll be fewer mosquitoes,” quipped walk leader Dr. Elizabeth Wells, Associate Professor Emerita of Botany at the George Washington University. Her commentary was engaging and wide ranging, covering plant taxonomy, reproduction, structure, pollination, predation, host plants and more.
Swamp dogwood Dr. Wells first pointed out the giant ragweed (Ambrosia trifida) with yellow, male, candelabra-like flowers along the Marina Road, noting that its wind-dispersed pollen is a major trigger of hay fever. “The purpose of a flower is sex,” she explained.
There were clear signs of fall. Swamp dogwood (probably Cornus amomum) leaves were becoming burgundy red. Pokeweed (Phytolacca americana) berries were transitioning from green to deep purple. These are favored fruits of many birds, though they are toxic to humans.
Wild rice Wild rice (Zizania aquatic) was billowing in the wind. The 10-foot-tall wild lettuce (Lactuca canadensis) by the Haul Road (pictured top left with Dr. Wells) was in its flower stage. Dr. Wells told the group that the plant oozes sap if you crunch the leaf. It did.
Smooth sumac Smooth sumac (Rhus glabra) leaves were turning yellow-orange and red. This plant has pinnate, compound leaves and Dr. Wells cautioned people to not confuse the smooth sumac with the non-native tree of heaven (Ailanthus altissima). The conical clusters of dark red fruit of the smooth sumac are distinctive and punctuate the woodland and wetland’s edge along the Haul Road.
Cardinal flower
Sycamore tree with scaly bark Dyke Marsh’s sycamore trees (Platanus occidentalis), trees that thrive near water, were displaying their scaly bark. On the subject of trees, Dr. Wells said, “The green ash (Fraxinus pennsylvanica) is popular to chew on if you are a beaver.” There was evidence of chewing.
The dark purple flowers of New York ironweed (Vernonia noveboracensis) bobbed in the wind. Cardinal flowers (Lobelia cardinalis) sprang out of the wetland, sporting their bright red hues. “They are humming bird pollinated,” Dr. Wells commented. A few spatterdock or yellow pond lily plants (Nuphar luteum; N. sagittifolia) still had their yellow, golf-ball-shaped flowers.
The tall, large-leaved, yellow leafcup impressed the walkers. On the subject of yellow, the group spotted the vine dodder (Cuscuta gronoviii) clumped along the shoreline like a wad of orange spaghetti.
Swamp marsh mallow 
Honey locust thorns Along the boardwalk, the crimson-eyed rose mallow or swamp marsh mallow (Hibiscus moscheutos) was in fruit, its flowers gone for the season. The swamp milkweed (Asclepias incarnata), a host plant for monarch butterfly caterpillars, sported soft pink flowers. Many sensitive ferns (Onoclea sensibilis) lined the boardwalk. Dr. Wells commented that their common name comes from the fact that they are among the first to die as the frost comes.
Especially imposing was the honey locust tree (Glendistica triancanthos), with four-to-five-inch sharp thorns poking out of the trunk. “This tree may have evolved with the big herbivores,” Dr. Wells said. “The thorns protected the tree so that the predators could not eat the fruit,” she theorized. Even the honey locust seedlings springing up nearby sported inch-long spines.
More than Plants
Hornet's nest 
Ed Eder and Margot Poole observe the nests of the fall webworm. FODMers spotted two monarch butterflies (Danaus plexippus), probably migrating south, and a big gray hornet’s nest high up in the trees. Bald eagles (Haliaeetus leucocephalus) and ospreys (Pandion haliaetus) soared overhead.
As the walk ended where the Haul Road trail meets Marina Road, FODMers studied the nests of the fall webworm (Hyphantria cunea), a native moth that weaves webbed nests on tree limbs in late summer and fall. “It is not harmful to trees,” Dr. Wells noted.
There is much to learn in the Dyke Marsh Wildlife Preserve.
Photos courtesy of Glenda Booth.
