Porophyllum ruderale var. macrocephalum (DC.) Cronq.

Porophyllum macrocephalum DC. Prodr. 5: 648. 1836
KUinia glandulosa Moc. & Scsi^-; DC Prodr. 5: 648, as synonym. 1836.
An erect annual; stem 5-10 dm. high, glabrous, branched above; leaves alternate; petioles slender, 1-2 cm. long; blades broadly oval or obovate, rcpand, 1-3 cm. long, thin and pale; glands oblong, conspicuous, along the margins, one in each sinus; heads solitary at the ends of the branches; peduncles clavate, 2-7 cm. long; involucre at first cylindric, 20-22 mm. high, 5-6 mm. broad, in age turbinate and broader; bracts mostly 5, linear, acute or obtuse, with 2 rows of linear glands; corollas about 12 mm. long; tube pale, many times longer than and gradually passing into the purple funnelform throat; lobes lanceolate; achenes 12-13 mm. long, hispidulous; pappus sordid-brown, fully 1 cm. long; bristles minutely scabrous.
Typb loc.lity: Near Villalpando, Mexico.
Distribution: Arizona, and throughout Mexico to Panama; also in Ecuador.