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LOMENT OF THE MOMENT:
ANOTHER PEA IN THE PATCH

A couple of weeks ago, we wrote about finding at Hilton Pond Center an especially interesting plant--the Littleleaf Sensitive Brier, whose leaves fold up if touched. We mentioned that this sprawling vine was in a large plant group, the Fabaceae--once called the Leguminosae--and also known as the Pea or Bean Family. These are the legumes--plants whose roots contain bacteria that absorb atmospheric nitrogen and enrich the soil. Most legumes are herbaceous and relatively small, but some get big and woody--as in the case with Mimosa trees imported from Asia. Among the more familiar native wild peas are Partridge Pea and all the clovers and vetches, plus trees such as the Redbud and Honeylocust.

We have several native legumes here at the Center and were reminded of one in particular this week when we came back to the old farmhouse after strolling the trails at dusk. We didn't actually see the pea plant itself--light was waning by the time we finished our walk--but the evidence we found was very conclusive; chances are you, too, know what plant we encountered even if you haven't ever noticed its flower. Rather than revealing the name of our particular pea plant, however, we thought we'd offer some clues to see if you can guess what was growing near Hilton Pond that we could identify without seeing the actual plant. (No fair peeking at the end of this essay!)

All text & photos © Hilton Pond Center

CLUE #1: The first clue is the photo above, which portrays a delicate lavender-pink flower configured like a typical pea: two fused petals that resemble ears, and two petals below that are rolled into an open tube that contains the fifth unpaired petal. Within the tube are the plant's reproductive parts. What isn't indicated by the photo is the actual size of the blossom; it's a mere three-eighths of an inch tall by a quarter-inch wide--which is why you may have overlooked it.

CLUE #2: The next clue is the plant's leaf (above). Like many peas, the leaf of our mystery plant is compound--in this case there are three oval, slightly pointed leaflets reminiscent of clover. The leaf petiole is slightly fuzzy, and the midribs and side veins of the leaflets are a paler green than their blades. This clue may not be all that useful because so many different kinds of plants have tripartite compound leaves. Nonetheless, the leaflets do provide an alternate common name for our plant in question--Trefoil--although that's probably not what most people call it.

CLUE #3: Our third clue is a photo of the plant itself (left). From its topmost blossom to the ground, the plant is about three feet tall with numerous side branches. We know from many years of observation at Hilton Pond Center that this plant is a perennial, even though it isn't at all woody and dies back to the substrate each year. (We haven't dug one up, but we suspect the root of this plant is tough and fibrous.) As indicated in the photo, our mystery plant grows best in open, sunny places; it's sometimes found in old fields and along country roadsides. The photo also shows that the leaves have rather short petioles and grow close to the stems, and that the tiny pinkish-lavender flowers are more or less clustered on leafless stalks.

CLUE #4: A closer look at the photo above shows another typical characteristic of members of the Pea Family; to belabor the obvious, they produce pea pods. In our mystery plant, the pods are not cylindrical as in string beans or snap peas, but are long and flattened with the peas separated into "loments"--segments that contain one seed each. The photo below provides a better look.

One fertilized flower on our mystery plant will produce 3-5 loments that start out being pale green and transected by darker green veins that bring nutrients to the peas as they develop. A second photo (below) uses backlighting to reveal the immature peas, i.e., the seeds of the plant that show as dark shadows at the center of each loment. As the peas mature, the skin of the loments becomes dark green and leathery, and the constricted area between them turns brown and becomes brittle.

CLUE #5: There is one characteristic of the loments obvious in the two photos above: They are edged with what appear to be tiny white hairs. In the photo below we provide a closer view of these hairs--which actually cover the entire loment. You can also see that the connection between the center loment and the one to its left has broken, which means the left loment is free to drop off the plant. But guess what? It almost never just falls to the ground.

CLUE #6: The much-enlarged photo (below right) is the left margin of the loment in the photo above. What looked at lower magnification to be little white hairs are actually tiny transparent hooks--devices that allow the loment to attach to fur or pantleg (or dark brown sock, above) when an animal barely brushes against our mystery plant. The little hooks grab hold with amazing stick-to-itiveness and passing animals do the plant a favor by transporting its ripened seeds to a new habitat some distance from the parent.

No matter what you call it, the plant produces seeds that are true hitchhikers, and almost anyone who has walked an old field has met our mystery plant--one whose identity you may have guessed by now. It goes by a variety of very descriptive names: Beggar-Ticks, Tick-Trefoil, Tick-Clover, Stick-tights, and--our preferred appellation--Beggar-Lice. All these common names refer to the seed pods latching into the passerby like some little arthropod parasite--a tick or a louse.

Worldwide (except Europe) there are nearly 300 species of Beggar-Lice, all in the genus Desmodium. They are differentiated--often with considerable difficulty--by the structure of their flowers and shapes of their leaves and loments. One of nearly two dozen Carolina species is Naked-flowered Tick-Trefoil, D. nudiflorum, whose root was chewed by Cherokees to relieve tooth and gum problems. (Based on the complex key in Radford's Manual of the Vascular Flora of the Carolinas, we weren't able to come to a conclusive identification of the specimen on this page and welcome any suggestions as to which species it might be.) Incidentally, Desmodium comes from a Greek word meaning "chain," which some say refers to the flower's jointed stamens; we always thought it more appropriately describes the chain-like arrangement of the seed-pod loments.

When we returned from our sunset walk around Hilton Pond this week, we looked down at our trousers and immediately knew we'd had an encounter with Beggar-Lice. Our pantlegs were plastered with dozens and dozens--probably hundreds--of little loments that we had to remove one at a time. Normally our trails are clear of such vegetation, but heavy rains spawned by recent hurricanes made the flower stalks grow so tall and lush they fell across the path--right where each little pea in the patch could hitch a free ride courtesy of the human who dislodged its "loment of the moment."

All text & photos © Hilton Pond Center

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* = New species for 2004

WEEKLY BANDING TOTAL
5 species
11 individuals

YEARLY BANDING TOTAL
(2004)
52 species
1,730 individuals

BANDING GRAND TOTAL
(since 28 June 1982)
123 species
45,035 individuals