BLAKE—REVISION OF TITHONIA. 429 
cm. high, 2 to 2.4 cm. thick; involucre 3-seriate, strongly graduated, 12 to 16 mm. 
high, the phyllaries obovate to cuneate-obovate, bluntly rounded or barely acutish, 
tuberculate-hispidulous chiefly on the exposed portions and gland-dotted, sometimes 
sparsely hispid, strongly indurate, pale, and vittate to middle, with broader herbaceous 
apex, the inmost submembranaceous-herbaceous above and 6 to 8 mm. wide; rays 
apparently about 8, yellow, oblong-oval, 2 cm. long, 6 mm. wide; disk corollas 
glandular-hispidulous below, 6 mm. long (tube 0.6 to 0.8 mm.); pales subglabrous, 
abruptly cuspidate-acuminate, with a tooth on each side below the cusp, 8 to 10 mm. 
long; achenes subquadrangular, blackish or mottled, glabrous or sparsely appressed, 
pilose, 5 to 6 mm. long; pappus none, or in achenes of the same head of about 6 basally 
united dentate squamellae 0.6 to 0.8 mm. long. 
Type LocaLiry: Las Palmas, San Luis Potosf. 
SPECIMENS EXAMINED: 
San Luis Porosi: Las Palmas, October 15, 1890, Pringle 3675 (type; G). 
Limestone hills, Las Palmas, 1894, Pringle 6143 (K, N). 
Tithonia brachypappa is easily recognized by its auriculate-decurrent petiole bases. 
This species is remarkable in showing in the same heads calvous glabrous achenes and 
others which are pubescent, and have a pappus of several basally united squamellae 
without awns. 
4. Tithonia thurberi A. Gray, Proc. Amer. Acad. 8: 655. 1878. 
Tithonia palmeri Rose, Contr. U. 8S. Nat. Herb. 1: 104. 1891. 
Urbanisol thurberi Kuntze, Rev. Gen. Pl. 1: 371. 1891. 
Rather slender branching annual, 0.5 to 2 meters high; stem whitish, striate, sparsely 
or rather densely tuberculate-hispid-pilose with spreading hairs and finely hispidulous, 
glabrate; leaves opposite below, alternate above, the blades 5 to 28 cm. long, 3 to 27 
cm. wide, ovate to broadly triangular-ovate, unlobed, short-pointed to acuminate, 
cuneately decurrent into the petiole from a cuneate to broadly cordate base, thin, 
triplinerved, crenate-dentate with low, broadly triangular, mucronulate teeth, above 
deep green, tuberculate-hispidulous with incurved hairs and especially along the 
veins tuberculate-hispid-pilose, beneath paler green, rather sparsely granular or 
hispidulous and along the veins hispid-pilose; petioles margined to the slightly 
ampliate, not decurrent base, 2 to 10 cm. long, the margin irregularly toothed in the 
larger leaves; peduncles striate, fistulose, spreading-hispid-pilose and finely hispid- 
lous, 30 cm. long or less; heads 2.5 cm. wide or more; disk 1.5 to 2 cm. high, 1 to 2.4 
em. thick; involucre 3-seriate, graduated or obgraduated, 1 to 2 cm. high, the two 
outer series of phyllaries lanceolate, oblong-ovate, or obovate, acute to acuminate, 
tuberculate-hispid-pilose and hispidulous, with indurate vittate base, usually con- 
tracted above, and shorter to longer, ovate to triangular-ovate, loose, herbaceous tip, 
the innermost broadest, with short, triangular-ovate, submembranceous-herbaceous, 
merely granular or strigillose, obtuse or mucronulate tip; rays about 8, orange- 
yellow, oval-oblong, about 7 to 10 mm. long; disk corollas glandular-pilosulous 
especially below, hispidulous on teeth, 6.2 mm. long (tube 1 mm.); pales nearly 
smooth, striate-ribbed, with a tooth on each side below the abruptly cuspidate- 
acuminate tip, 1 to 1.5 cm. long; achenes oblong-obovate, thickened, appressed- 
pilose, 8.5 mm. long; awn solitary (on outer angle of achene), linear-subulate, 5.8 
to 8 mm. long; squamellae about 4 to 8, lanceolate, very unequal (the central shortest), 
4 mm. long or less. 
Type LocaLiry: Magdalena, Sonora. 
SPECIMENS EXAMINED: 
Sonora: Magdalena, October, 1851, Thurber 910 (type collection; G, K). Along 
watercourses and in canyons, Alamos, September, 1890, Palmer 721 (type 
collection of 7. palmeri; G, K, N). 
This species may be recognized by its usually sparsely hispid-pilose stem, charac: 
teristic involucre, and pappose achenes. 
