Prionosciadium megacarpum Coult. & J. N. Rosc

Prionosciadium megacarpum Coult. & Rose, Contr U. S. Nat. Herb. 3: 308. 1895.
Plants stout, 2-5 m. high, the foliage and inflorescence hispidulous or villous; basal leaves ovate in general outline, excluding the petioles 9-12 dm. long, 3-ternate, the leaflets ovate to lanceolate, acute at the apex, cuneate at the base, 10-25 cm. long, 6-10 cm. broad, finely crenatedentate and often somewhat lobed toward the base, confluent by the broadly entire-winged rachis; cauline leaves opposite, 1-2-ternate, greatly reduced upward with smaller and narrower leaflets; inflorescence of successive verticils of peduncles; peduncles short, 6-13 cm. long, each whorl subtended by a pair of leaves; involucre of several scarious, villous, linear or filiform bracts 5-10 mm. long; involucel of several scarious, villous, filiform bractlets 5-10 mm. long, longer than the flowers but shorter than the fruit ; fertile rays 1 5-20, spreading-ascending, subequal, 2-5 cm. long, those of the lateral umbels often fewer and shorter; fertile pedicels 1-4, 5-8 mm. long; flowers white; fruit broadly oblong, retuse at apex and base, 15-20 mm. long, 10-12 mm. broad, occasionally shortened and nearly orbicular, up to 15 mm. broad, glabrous, the dorsal ribs narrowly winged, the lateral broadly thin-winged, the wings about twice as broad as the body; oil-tubes large, 3 in the intervals, the middle much the largest, about 6 on the commissure; seed sulcate under the intervals, the face strongly involute.
Type locality: Sierra de San Felipe, Oaxaca, 7.500 feet, Pringle 4688. Distribution: Oaxaca {Conzatli 4005, C. L. Smith 886).