Illinois bundleflower
Desmanthus illinoensis                                      

Identifying Characteristics:

Seed: oblong or slightly triangular, brown, flattened

Seedling:  typical legume; cotyledons large; first leaf once-compound

Mature Plant: fibrous roots form thickened overwintering rootstock; erect or spreading stem, strongly angled, glabrous to hirsute; alternate leaves evenly bipinnate, saucer-shaped gland between lowermost pinnae; inflorescences form dense head on tips of upper branches, greenish white and globular

Method of Propagation: seed

Life Cycle: perennial herb

References: 
Bryson, Charles T. & Michael S DeFelice. "Weeds of the Midwestern United States & Central Canada."