Zebras, Spiders, and an Interesting Vine

August 7, 2015.  We had two-and-a-half inches of badly-needed rain yesterday afternoon at my house in Columbia, but it’s obvious not a drop fell here at the park, only fifteen miles away. It reaffirms that summer rainfall in South Carolina is local.

Since my last visit five days ago, I see that the squirrels have begun feeding on green pine cones, as indicated by the leavings scattered over the handrails and decking of the high boardwalk. I’m  impressed with any animal that can take on and dismember the hard, spiny cones.

Five-lobed cucumber vine, Cayaponia quinqueloba.

I find an interesting vine growing on the trail near Wise Lake. The bright red, oblong fruits, about three-fourths of an inch long, stand out like beacons against the green foliage and grab my attention first. They are doing their job as color attractants in order to get birds to eat them and disperse the seeds (John Nelson, curator of the A.C. Moore Herbarium at the University of South Carolina, reports that they have a very bitter taste). The red color and bitter taste may be an indicator of a high quality food for migratory birds which will soon be passing through the Congaree in large numbers. High quality bird fruits typically have a bitter or sour taste and are high in fats, rather than sugars, and enable migratory birds to undertake their arduous fall migrations that take them thousands of miles away from their breeding grounds in North America. Some other high quality bird fruits now ripening in the swamp include spicebush, Virginia creeper, and swamp tupelo.

The vine is five-lobed cucumber, Cayaponia quinqueloba, a tropical species with close relatives in South America. It is a member of the famous Cucurbitaceae family which includes such notable representatives as squash, cucumber, gourds, pumpkins, cantaloupe, and watermelon. All of these are vine plants, and botanically speaking, the melons, gourds, cucumbers and squashes themselves are called a pepo, one of my favorite botanical terms. A pepo is defined as a soft fruit, without internal partitions or septa (as found in citrus fruits), surrounded by a hardened rind. Like all family members, five-lobe cucumber is pollinated by bees, although some botanists think in their original tropical haunts they were pollinated by bats.

My interesting vine is one of the thirty plus species of vines found at Congaree, more than any other national park.

After crossing the bridge over a very dry Hammond Gut, I walk for the first half mile on a southwest bearing that takes me through a series of ridges and swales, the latter being old river channels from thousands of years old, the former, old river banks. This is a nice section of old-growth forest dominated by large sweetgums, green ash, and sugarberries. The ground cover, unfortunately, is dominated by lush clumps of exotic Japanese stilt grass, Microstegium vimineum.

Stilt grass, Microstegium, has unfortunately become widespread as a ground cover at Congaree.

I get a whiff of bananas and see the source, a ripe fallen pawpaw, partially chewed by squirrels or rodents. It’s the first fruit I’ve seen this morning, despite walking by hundreds of pawpaw trees.

As I get closer to the river, the ridge and swale topography merges into flat terrain dominated by even-aged, medium-size sweetgums with a few scattered cherrybark oaks. A forest stand dominated by even-aged sweetgum like these suggests the possibility of an antebellum clearing of some sort, possibly an agricultural field or other such opening.

I come out at Pearson’s Pond, probably named for Philip Pearson, one of the early surveyors in Richland County who surveyed some of the first Congaree land grants before and after the Revolution. The pond has not had any water in it for four or five months, and the bottom has been thoroughly chewed up by rooting pigs. The trees are mostly small to medium-sized water tupelo and red maple. I see no large rotten stumps of virgin cypress that are characteristic of many other ponds and sloughs in the park.

The next pond to the west of Pearson’s is Duck Pond, named by Harry Hampton. It has a number of large old stumps that appear to be water tupelo, all of which were cut at ground level rather than above the buttress as most cypress were. I don’t think water tupelo had much commercial value a hundred years ago when the virgin cypress stands were being cut and don’t understand  why they would be cut at ground level as it made for extra work with little economic return. The insides of the old stumps are recessed a foot or more below ground and filled with sediment that has settled in over the years.  This could explain why the old stumps are now at ground level: a hundred years ago the stumps may have been two feet above ground level.

The north loop of the ten-mile River Trail runs along the western edge of Duck Pond. It is one of the most unused trail sections in the park, since most hikers prefer to stay on the south section and get to the river quicker.

A hard to see spiny-backed spider in the middle of this photo by John Grego.

I have been walking for much of the morning and early afternoon through numerous spider webs, always at face height. Many of these webs belong to Verrucosa arenata, the triangulate orbweaver or “arrowhead spider,” in reference to the white triangular patch on its abdomen. Other webs belong to spiny-backed spiders in the genus Micrathena. I see not a single golden silk spider today.

As I attempt to unwrap one particularly irksome web that has ensnared me, accompanied by low curses, I see a zebra swallowtail butterfly, with notably long tail streamers, flitting through a clump of sunlit pawpaws. I have to ask myself, why don’t butterflies get caught in spider webs? I know some do on occasion, but still, you’d think there would be a lot more trapped in webs out there.

I watch the zebra as it flits from one pawpaw to another, pausing briefly on the leaves as if wanting to lay eggs. It comes closer and lights on the edge on one leaf and bends its abdomen underneath the leaf, then quickly flies off. I walk over, look under the leaf, and sure enough, find the round, light green egg she just laid, about the size of a pin head. Despite the abundance of both pawpaws and zebra swallowtails at Congaree, I have yet to see my first zebra caterpillar.

It is early afternoon, clouding up a bit, and I hear a distant rumble of thunder.  On the way back I walk the last twenty minutes in a light rain but barely get wet since a lot of it is intercepted by the dense canopy overhead.