phyllaries about 6. oblong-obovate, apiculate, blunt, inner series fewer, shorter 

 and narrower; receptacle slightly convex, chaffy throughout, the linear pales 

 bristlelike; ray flowers numerous, pistillate, fertile, the linear rays minute and white; 

 disk flowers numerous, perfect, fertile, the corollas minute and whitish; achenes 

 laterally compressed, rhombic in transection, narrowed to the base, each side with 

 an elongate medial patch of verrucose projections; pappus absent or represented 

 merely by slight points above the corners of the achene. 



In mud at the edges of fresh water bodies, nearly throughout our area though 

 rare in the Trans-Pecos and the higher parts of the Plains Country of Tex., 

 summer-fall; warmer parts of the world. 



Some authors claim that the species is indigenous to the Old World and intro- 

 duced in the New World. 



25. Tithonia J. F. Gmel. 



About 10 species in southwestern United States, Mexico, Central America and 

 the West Indies. 



1. Tithonia Thurberi Gray. 



Slender moderately branched annual to about 2 m. tall; stems whitish, striate, 

 sparsely to densely hispid-pilose with spreading tuberculate-based rather coarse 

 hairs interspersed with finer ones, eventually glabrate; lower leaves opposite, 

 the upper ones alternate; petioles 2-10 cm. long, the margin irregularly dentate 

 on large leaves; blades ovate to broadly triangular-ovate, acute to acuminate, 

 to 27 cm. long and wide, cuneately decurrent along petiole from a cuneate to 

 broadly cordate base, crenate-dentate with mucronulate teeth, deep-green and his- 

 pidulous with incurved hairs above, pale-green and sparsely granular or hispidulous 

 and hispid-pilose on veins beneath; peduncles striate, 1-3 dm. long, spreading 

 hispid-pilose and finely hispidulous; heads 2.5-3.5 cm. wide; involucres of gradu- 

 ated bracts in 3 series, 1-2 cm. high; outer bracts lanceolate to obovate, acute to 

 acuminate, pilose, indurated below, herbaceous at tip; innermost bracts broadest, 

 submembranaceous, obtuse to submucronulate at tip, only granular or strigose; 

 rays 5 to 10, orange-yellow, oval-oblong, 7-12 mm. long, 4-6 mm. wide; disk 

 corollas about 6 mm. long, hispidulous on lobes, the tube about 1 mm. long, the 

 throat cylindrical; receptacular bracts 1-1.5 cm. long, oblong, abruptly acuminate 

 with a small tooth on each side near tip, striate-ribbed, smooth; achenes oblong- 

 obovate, about 9 mm. long; pappus awn solitary on outer angle of achene, linear- 

 subulate, 5.5-8 mm. long; squamellae 4 to 8, unequal, lanceolate, 4 mm. long or 

 less. 



In rich moist or wettish soil near and along streams and ditches, and in muddy 

 soil on margin of lakes and reservoirs, usually in shade, in Ariz. (Pima and Santa 

 Cruz COS.), Aug.-Sept.; s. to cen. Son. 



26. Spilanthes Jacq. 



A world-wide genus of about 60 species. 



1. Spilanthes americana (Mutis) Hieron. var. repens (Walt.) A. H. Moore. Creep- 

 ing SPOT-FLOWER. Fig. 761. 

 Perennial herb extensively creeping and rooting at many nodes, also rhizoma- 

 tous, only the flowering branches ascending: leaves opposite; blades narrowly 

 rhombic-ovate or deltoid-ovate, 2-4 cm. long, serrate; petiole 1-2 cm. long; heads 

 solitary, about 1 cm. high, on naked axillary peduncles 5-15 cm. long; involucre 

 about 5 mm. high, of 2 series of subequal linear phyllaries; receptacle very high- 

 conic, chaffy throughout, the pales enfolding the flowers and about equaling them; 

 ray flowers few, pistillate but infertile; rays only a few mm. long, yellow, irregu- 



. 1649 



