It’s not an easy plant to spot. Maximum height is around one foot and the compound leaves easily blend with the surrounding vegetation. The tiny yellow flowers usually hang down from the stem and are hardly noticeable as you walk by.
The leaves of this plant fold up when disturbed, just as with the Sensitive Plant commonly kept as a house plant. The wild plant takes a little more abuse before closing up. The leaf in the lower right of the photo has closed as a result of my touch. I’ve always been fascinated by Sensitive Plants. When I was six, my mother took me along when she visited a friend who had many Sensitive Plants around her house. I got into trouble for going around the house and closing the leaves on all of her plants.
The Wild Sensitive Plant grows in the typical dry open prairie environment and is said to survive in a variety of conditions. At Blue Jay Barrens, these plants are only found in the low pH soils formed over shale bedrock.
Between the base of the leaf and the first set of leaflets is a large, dark colored gland, roughly shaped like a mushroom. The gland secretes a sweet liquid that is highly attractive to insects.
Of course, the insect most likely to exploit such a source is the ant. As they do with other food sources, the ants provide an added level of protection to the plant.
The flat pods of the Wild Sensitive Plant produce about seven to nine seeds. The plant is an annual, so a good crop of seeds is important to its continued survival. Not all seeds germinate their first year. Many remain in the soil and may not germinate for several years. This provides some insurance against a disastrous growing year.