This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Erect perennial glabrous branching herbs, with pinnately decompound leaves, and compound umbels of white flowers. Involucre none, or of a few short bracts. Involucels of several narrowly linear bracts. Calyx-teeth obsolete. Petals with an infolded tip. Stylopodium depressed-conic. Fruit oval or oblong, dorsally flattened. Carpels with prominent approximate dorsal and intermediate ribs, the lateral ones broadly winged and conspicuous. Oil-tubes mostly 2-3 in the intervals, and 4-8 on the commissural side. Seed-face slightly concave, its back strongly convex. [Greek, hemlock-parsley.]
About 10 species of the north temperate zone. Besides the following, some 3 others occur in western North America. Type species: Conioselinum tataricum Hoffm.
Athamanta chinensis L. Sp. Pl. 245. 1753.
Selinum canadense Michx. Fl. Bor. Am. 1: 165. 1803.
C, ( ?) canadense T. & G. Fl. N. A. 1: 619. 1840.
Conioselinum chinense B.S.P. Prel. Cat. N. Y. 22. 1888.
Stem terete, striate, 2°-5° high. Lower leaves long-petioled, the upper nearly sessile, all decompound into linear-oblong acutish segments; petioles sheathing; umbels terminal and axillary, 2 - 3' broad, 9-16-rayed; rays rather slender, 1 1/2-2 1/2 long; pedicels very slender, 2"-3" long; fruit prominently ribbed, broadly oval, about 2" long.