T. nodosa: annual; stems procumbent or spreading, scarcely a foot long; leaves twice pinnate, with small, narrow, pointed segments; umbels forming little heads, closely sessile, opposite to the leaves, composed of 2-3 exceedingly short, scarcely distinct rays, sometimes of a simple cluster; fruits covered with short, straight or hooked bristles. - Roadsides and waste places. Fl. May, June.
T. Anthriscus: annual; stem erect, 2-3 feet high, with slender, wiry branches; leaves once or twice pinnate, the segments lanceolate, pinnatifid, or coarsely toothed; umbels on long slender peduncles, of 3-8 rays; involucres, both general and partial, of small subulate bracts, one close under each ray; fruit a small burr. - Hedge Parsley. - Hedges,roadsides, and waste places. Fl. July, August.
T. infesta: annual; smaller and more spreading than the last; general involucre entirely wanting or reduced to a single bract, often lanceolate; bristles of the fruit less curved, with a minute hook at the top. - Cultivated and waste places. Fl. July, August.