Tuesday, September 11, 2012

Velvetleaf Ticktrefoil (Desmodium viridiflorum)?

August 25th, 2012. Another visit to the Piedmont National Wildlife Refuge. As we were driving down Starr Road from GA-83 through the Oconee National Forest in Jasper County, we saw a leafless stem covered with flowers. The flowers were still in good shape so we stopped to take a closer look. It was a Desmodium species but which one? There are so many. I came to the conclusion that this is Desmodium viridiflorum (Velvetleaf Ticktrefoil) but welcome any correction.
This was a very robust plant. The stem reached about 4 feet from the vegetative part of the plant which stood about 2 feet high.

The tip of the stem which was quite thick and strong.

The leaves were about 1-1/2 inches long and roughly ‘velvety’

Flowers of the Desmodium species have ‘clear’ pink petals, in contrast to the opaque, ‘streaky’ pink and white flowers of the Lespedeza species and  have two ‘eye spots’ at the base of the banner petal.

This view gives a better view of the ‘eye spots’ and shows the fused stamens. A free stamen is also visible

An even better view of the fused and free stamens and the calyx.

Seed pods of a Desmodium species (not D. viridiflorum) showing the typical branch or chain that gives the genus its name. The seed pods have hooks that act like Velcro and stick to the fur of passing animals or clothing on humans

A sock to which desmodium seed pods have attached showing how effective this method of seed dispersal is. It takes quite a while to pick these off.

Desmodium viridiflorum (Velvetleaf Ticktrefoil, Velvety Tick-clover) is native to the United States, where it’s found in states southeast of a line from Connecticut-Pennsylvania west to Missouri and southwest to Oklahoma and Texas. In Georgia, it’s been documented in several counties throughout the state.
Click on an image to view a larger image

Identification resources:
- Name that Plant: Native and Naturalized Plants of the Carolinas and Georgia: Desmodium viridiflorum (Velvety Tick-clover)
- Missouri Plants: Desmodium viridiflorum
- Virginia Tech Weed Identification Guide: Desmodium viridiflorum

- United States Department of Agriculture Plants Database: Desmodium viridiflorum (Velvetleaf Ticktrefoil)
- University of North Carolina Herbarium: Desmodium viridiflorum

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