It grows wild near Lake Thurmond ( a little west of the trail) but it looks similar to some of the plants on your chart. Lots of our wild plants are on your chart.
I have no idea what you mean by my chart. I have no chart available.
I cannot be certain what this plant is without seeing pictures of the whole plant and of the leaves. My best guess right now is Tephrosia spicata, spiked hoarypea. It is certainly a legume with terminal flowers but that includes many others. Sorry I cannot be of more help. If you have any leaf pictures, resubmit.
Dr. Steven Hill, Botanist, SCNPS