Prionosciadium humile Rose

Prionosciadium humile Rose, Contr. U. S. Nat Herb. 12: 302. 1909.
Peucedanum(?) madrense S. Wats. Proc. Am. Acad. 25: 150. 1890. Not Prionosciadium madrense S. Wats. 1888.
Plants slender, 4—6 dm. high from a slender, short, branching horizontal rootstock bearing dead leaf-sheaths, glabrous and somewhat glaucous except for the scaberulous inflorescence; basal leaves ovate to deltoid in general outline, excluding the petioles 1-2 dm. long, 1-2-ternate or ternate-pinnate, the leaflets ovate, acute or obtuse at the apex, truncate or cuneate at the base, 4-6 cm. long, 3-4.5 cm. broad, distinct or the distal confluent, petiolulate, serrate, incised and often 3-lobed toward the base, green above, glaucous beneath, the rachis essentially unwinged; petioles slender, 7-12 cm. long, dilated and sheathing at the base, the sheaths elongate, oblong, scariouswinged; cauline leaves reduced upward and simply ternate; inflorescence of 1-several terminal and axillary, alternate peduncles; peduncles rather stout, 1-2 dm. long; involucre wanting; involucel of several linear-lanceolate bractlets 3-5 mm. long, shorter than the flowers and fruit; fertile rays 8-12, spreading-ascending, subequal, 2.5-4 cm. long; fertile pedicels 3-9, 5-8 mm. long; calyx-teeth obsolete; flowers greenish-yellow, red-veined; fruit oblong to oval, rounded at the apex, subcordate at the base, 12-14 mm. long, 6-8 mm. broad, glabrous and glaucous, the dorsal ribs prominent, the lateral broadly thin-winged, the wings broader than the body; oil-tubes solitary in the intervals but with some smaller accessory ones, 2-6 on the commissure; seed-face slightly concave.
Type locality: "In the Sierra Madre, near Monterrey," Pringle 2211. Distribution: Nuevo Le6n (Pringle 10,204).