Rayless Chamomile
Matricaria matricarioides (Less.) Porter

Collected on the Weippe Prairie in Clearwater Co., Idaho, on 12 Jun 1806. Sheet PH-LC 142 (Moulton 110b), long considered a Lewis and Clark specimen, appears to be garden material and was probably raised from seed gathered by Thomas Nuttall in 1811. Synonymy: Santolina suaveolens Pursh. (Source)