Vitaceae Seedlings; A Mystery No More

Sampling plants in quadrats is a challenging endeavor. It requires a taste for botany in its most raw and primitive state. Plants encountered in quadrats are almost always sterile and range from newborn seedlings to the withered remains of plants that may have senesced earlier in the year; and everything green in between. The field botanist spends countless hours in a growing season on his knees, head buried in vegetation, straining to use a hand lens at ground level in order to examine such subtleties as the red calluses on the teeth of Ceanothus americanus seedlings or the length of the ligule that separates Andropogon virginicus from Andropogon scoparius (Schizachyrium lacks taxonomic credibility when applied to Little Bluestem).
All this with the discomfort and sometimes fear that ticks, chiggers, horseflies, deerflies, yellow jackets, mosquitoes, gnats, spiders, snakes, falling limbs, storms, poison-ivy, heat and meth-heads illicit all around you. You know you have reached the pinnacle of a seasoned field botanist when you choose to examine a deftly teased Scleria achene between your fingers before you tend to the thousands of seed ticks that have just colonized your hand, or to wipe the searing sweat from your burning eye sockets.

In spite of this, the forests, woodlands, glades and prairies are our laboratories, where we test and untangle the differences in taxa by their simplest organs; their leaves and stems. Hard won are the tricks of our trade and they evoke an excitement that can be shared with few and appreciated by even fewer. After 12 years in the field, I am still a student of the flora and each day I am humbled by the myriad challenges of the trade.

I write this as a prerequisite for the information below in the hope that it will put the breadth of these findings into perspective. For each season a few new mysteries are solved; the knowledge that the Vaccinium can be distinguished by their venation patterns, that Impatiens can be discerned by the number of teeth on the leaf margins, that species in the genus Aristida actually have solid vegetative characters. This is the gold you can never mine from “the literature”. Sadly, it has no outlet.

One of the great unsolved mysteries in vegetative sampling has always been how to distinguish the cotyledons of Parthenocissus quinquefolia (Virginia Creeper) from Vitis aestivalis (Summer Grape). Both are members of Vitaceae (the grape family), both are commonly encountered and both germinate and persist throughout the summer. In the past, when these little groaners were encountered, they were entered onto the datasheet as “Vitaceae”; a moniker that lacks ecological significance and provides no information other than simple occurrence. This has all changed.

Earlier this summer I was innocently sampling a plot when what should appear within the boundaries of my quadrat but a bushel of Vitaceae seedlings. The first one I glanced at had three leaflets on the first true leaf emerging from between the cotyledons thus instantly giving it away as Parthenocissus. The next had one distinct leaf of a Vitis aestivalis. As I surveyed the quadrat and surrounding area I realized I was in an ocean of both species all with cotyledons intact and with one corresponding true leaf. Perhaps the tree above, lacking vines of either species, had been a turkey roost or an opossum hangout. Regardless, the area was strewn with an incredible density of both species in seedling form. I told myself that this was an opportunity not to be missed.

After a half hour of examining everything from stem thickness to overall color, I could find nothing consistent to differentiate these two beast and I had all but decided that my little observational study was as it had been, inconclusive. Then I noticed the broadly truncate-ovate bases of the Parthenocissus cotyledons and how the cotyledons were about as long as broad and thus rather deltoid in outline.

Comparing a Vitis seedling, I found the cotyledons of Vitis to be more rounded at the base and cleanly ovate in outline (longer than broad but broadest below the middle).

Twenty or thirty seedlings later, I was consistently and accurately using these characters to distinguish the two. I collected and pressed several examples and went about my merry way. For the remainder of the summer, as I have hiked to plots or walked between quadrats all over the Ozarks, I have kept an eye out for more seedlings and have found these characters to hold with 100 percent consistency. In fact, I don’t even pause anymore. They are so distinct that now I can’t imagine how this difference has gone undetected for so long.

Though this may seem insignificant in the grand scheme of nature and its study and though these findings will never grace the pages of Science, I smile every time I think of the simple hidden beauty that eluded field botanists for so long. Discoveries like this fuel my hope that some day field characters for such notorious complexes as Zizia aurea/Thaspium trifoliatum and Liatris aspera/scariosa/squarrulosa will seem as obvious as the vegetative differences between Impatiens capensis and I. pallida. The more we learn, the cleaner the data we collect. The cleaner the data, the better the management decisions based on these data will be. To me, this is science at its best; ever learning, ever revising and always hashing out the details regardless of the annoying gnat in your eye, the itch of poison ivy or the hundreds of chiggers slowly digesting the flesh from around your ankles. Afterall, science is stone.