Monographs Details: Tetragonotheca
Authority: Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Description:Genus Description - Heads radiate, the rays pistillate and fertile, light yellow; invol of 4(5) relatively large and leafy bracts, united at base; receptacle conic, especially in fr, its bracts subtending rays as well as disk-fls, thin, partly clasping the achenes; disk-fls perfect and fertile, the cor-tube expanded at base and covering the top of the achene; style-branches flattened, with rather long, hairy appendage; achenes quadrangular or subterete, scarcely compressed; pappus of several short scales, or none; coarse, taprooted perennial herbs with clustered stems, opposite, ± toothed, often clasping lvs and few or solitary heads. 4, U.S., Mex.