S. latifolium: stems glabrous, stout, erect, angular, 2-4 feet high; leaves pinnate, the lower very long, with 6-10 pairs of large ovate-lanceolate toothed segments; the upper shorter, with fewer and smaller segments; umbels large, of 15-20 rays, all terminal, general and partial involucres of several lanceolate often toothed bracts. - Ditches and edges of streams. Fl. July, August.
S. angustifolium: stems erect, branched, leafy, round, striated 1-3 feet high; leaves pinnate, with 8-10 pairs of un-equally-lobed ovate segments, deeply and sharply toothed; umbels numerous, mostly lateral, with 8-15, rarely more, rays; involucral bracts lanceolate, often toothed. - Ditches and shallow streams. Fl. August.