Poreleaf Dogweed

Lebetina porophyllum (Cav.) Rydberg
Pteronia Porophyllum Cav. Ic. 3: 13. 1794.
Dyssodia porophvlla Cav. Anal. Cienc. Nat. 6: 334. 1803.
Boebera Porophyllum H. B. K. Nov. Gen. & Sp. 4: 198. 1820.
? Adenophyllum capillaceum DC. Prodr. 5: 638. 1836.
? Schlechtendalia capillacea Moc. & Sesse; DC. Prodr. 5: 638, as synonym. 1836.
Boebera alternifolia Moc. & Sesse; DC. Prodr. 5: 639, as synonym. 1836.
? Dyssodia alternifolia Regel & Korn. Ind. Sem. Hort. Petrop. 1857: 41. 1857.
Adenophyllum Porophyllum Hemsl. Biol. Centr. Am. Bot. 2: 218. 1881.
Lebetina' porophylla A. Nelson, Bot. Gaz. 47: 435. 1909.
A branched annual; stems 3-7 dm. high, glabrous, striate, with ascending branches above; leaves alternate, 2-5 cm. long, pinnately parted into oblong or obovate toothed divisions, some of the teeth with long bristle-points; glands large, marginal in the rounded sinuses and nearly terminal in the lobes; heads corymbose-paniculate, with more leafy peduncles; involucre turbinate, 10-12 mm. high and nearly as broad; accessory bracts 15-20, pectinately divided into 3-6 pairs of bristle-like divisions; principal bracts about 20, acuminate, the horn 1 mm. long; ligules wanting or small, ascending, oblong; disk-corollas 5 mm. long, the cylindric tube and the trumpet-shaped throat subequal, the lanceolate lobes somewhat shorter; achenes 5 mm. long, striate; squamellae 6-7 mm. long, all dissected into 7-10 bristles.
Type locality: "Nova Hispania" [Mexico].
Distribution: Vera Cruz to Jalisco and Guatemala.