Thaspium trifoliatum (Linnaeus) A. Gray var. aureum (Linnaeus) Britton. Phen: Apr-May; Jul-Aug. Hab: Moist forests. Dist: NY west to MN, south to SC, AL, AR, and se. KS.
Origin/Endemic status: Native
Taxonomy Comments: Various workers have differed on the characters used to separate two varieties in T. trifoliatum. RAB and C separate the two strictly on petal color; F, however, allows var. aureum to sometimes have purple petals, seeming to regard the critical differences to be var. aureum's generally more robust size and larger fruits (4.5 mm long vs. 3-4 mm long). It is presently not clear how two varieties should be separated, or, indeed, if varieties are warranted. Though the ranges overlap, var. aureum is generally more northern and western, var. trifoliatum more southern and eastern.
Synonymy: = Ar, K1, K3, K4, S, Coulter & Rose (1900); = Thaspium trifoliatum (L.) A.Gray var. flavum Blake – C, F, GrPl, Il, MC, Mo2, Pa, RAB, Tn, W, WV, Cooperrider (1985); < Thaspium trifoliatum (L.) A.Gray – G, Mi, Ok, Va, Floden (2019)