Pea Family (Fabaceae). Prairie acacia is a native, perennial, warm-season, hardy, deep taproot legume. A smooth and small rounded shrub, forming colonies by means of woody rhizomes with aerial stems that are thornless and rarely over three feet tall. The plant has an attractive and delicate fern-like foliage which closes at night and when touched. Stems are thin, usually unbranched, glabrate, and ridged. Leaves are alternate, the blade divided into usually 3-12 pairs of segments, these again divided into 6-20 pairs of tiny leaflets. Flowers are small and white to creamy yellow. It has 5 petals and stamens numerous, long, and protruding. Flowers numerous, congested in rounded terminal clusters on long stalks arising from upper leaf axils. Fruit is brownish flat seed pod 4-7 cm (1.6-2.8 in) long and 6-8 mm (0.25-0.3) wide. Plant is similar in appearance to Illinois bundleflower, Desmanthus illinoensis, but the fruit and leaf structures are different.