54 Contributions from the Gray Herbarium 
Am. Bot. ii. 178 (1881). Tithonia pachycephala DC.! Prod. v. 585 
(1836). Gymnolomia megacephala Rob. & Greenm. var. simulans 
Rob. & Greenm.! Proc. Bost. Soc. Nat. Hist. xxix. 102 (1899). — 
Two varieties may be recognized. 
Var. genuina: achenio pubescente, cum pappo normali Viguierae 
praedito. — Tithonia pachycephala DC. 1.c. Viguiera pachycephala 
(DC.) Hemsl. lc. V. excelsa Gray in Wats. Proc. Am. Acad. xxii. 
426 (1887), not B. & H.— MEXICO: San Luis Porost: shady 
places near Morales, Sept. 1876, Schaffner 267 (G.); Jatisco: Rio 
Blanco, Sept. 1886, Palmer 532 (B. M., G., K., U. 8.); Guadalajara, 
Sept. 1886, Palmer 443 (B. M., G., K., Mo., U. 8.); barranca, 
Guadalajara, 10 Nov. 1888, Pringle 2175 (G.); hillsides near 
Guadalajara, 9 Oct. 1889, Pringle 2484 (B. M., G., K., Mo., U.S.); 
barranca near Guadalajara, 1370 m., 20 Oct. 1903, Pringle 11609 
(G., K., U. S.); Huejotitan, 1700 m., Oct. 1912, L. Diguet (Par.); 
road between Plateado and Colotlan, 5 Sept. 1897, Rose 3653 
(U. 8.); Chapala, 5 Oct. 1903, Rose & Painter 7633 .: S33 
Guanajuato: Guanajuato City, Mendez (rypE: Prod.).— Nearly 
all the above specimens, excepting the type, were distributed as 
V. excelsa. The two species are very intimately related, but the 
present plant seems consistently different in its greener leaves 
pubescent beneath almost entirely on the main nerves alone, and 
not between them. 
Var. simulans (Rob. & Greenm.), comb. nov.: achenio glabro, 
pappo nullo, capitulis paullo minoribus (3.5 em. latis). — Gymno- 
lomia megacephala Rob. & Greenm. var. simulans Rob. & Greenm. 
1. e.— MEXICO: Zacarecas: Sierra de los Morones, near 
Plateado, 2315 m., 1 Sept. 1897, Rose 2740 (typPE: G.). 
8. V. BUDDLEIAEFORMIs (DC.) B. & H. Herbaceous perennial, 
up to 2.6 m. high. Stem brown or purplish-tinged, densely tuber- 
culate-strigillose, rarely somewhat hispid-pilose in lines, panicu- 
lately branched above, bearing 8-90 heads in a panicle sometimes 
2.5 dm. wide. Leaves usually opposite to near the inflorescence- 
branches, narrow-oblong to oblong-ovate or lanceolate, the lowest 
ovate, acute, mucronate, cuneate to rounded at base, more or less 
distinctly serrulate to subentire, 3-nerved and reticulate-veined, 
above green, harshly tuberculate-hispidulous, beneath densely 
canescent-hispidulous, 6-15 em. long, 1.3-2.8 em. wide (the lower 
up to 6 cm. wide), on petioles 1-1.6 em. long. Heads cymosely 
