458 PROCEEDINGS OF THE AMERICAN ACADEMY. 



hairs : leaves lanceolate from a narrowed auriculate base, undulate to 

 sparingly and irregularly scabrous-pubescent upon both surfaces, 3 to 

 5 cm. long, 8 to 11 mm. broad: peduncles slender, pubescent, 3 to 7 cm, 

 long; heads often nodding, 1.2 cm. in diameter (including narrow yellow 

 entire or bidentate ligules) ; involucre shallow, saucer-shaped, the 5 divi- 

 sions united nearly to the middle, broad, scarious and ciliate at the 

 margin : fruit finely striate, punctate and slightly tuberculate, bearing 

 a well-developed hood surmounted by a slender recurved hispidulous 

 appendage not flanked by lateral teeth at the base. — Collected by F. H. 

 Lamb in sandy soil on Isla Piedra, Mazatlan, Sinaloa, 31 December, 

 1894, no. 361a. Mr. Lamb's no. 380 also from Mazatlan differs in hav- 

 ing no tubei'cles upon the fruit and in the obsolescent appendage, yet it 

 is probably of the same species. Type in herb. Gray. 



c. Pubescence copious, soft, long, villous : leaves ovate-lanceolate to ovate : ap- 

 pendage of the hood short : involucre gamophyllous only near the base. 



6. M. LONGiPiLUM, llobinson. Involucre externally villous, its 

 divisions acutish. — Proc. Am. Acad, xxvii. 173 (1892). — San Luis 

 Potosi, Prinyle, nos. 3639, 4537. 



= = Stems tending toward lignescence : roots at least in part perennial : species 

 of northern Mexico and southern United States. 



a. Heads rather small, (including the rays) about 1 to 1.2 cm. in diameter: 

 leaves conspicuously sinuate or pinnatifid : rays thin, short. 



7. M. ciNEREUM, DC. 1. c. (1836). Hood muticous. — Laredo, Texas, 

 Berlandier, who appears to have confused this with the variety ratnosissi- 

 mum, so that his numbers cannot be depended upon. 



Var. RAMOSissiMUM, Gray. Hood mucronate, — Syn. Fl. i. pt. 2, 

 239 (1884), in part. 3£ ramosissimum, DC. Prodr. v. 518 (1836). — 

 Near Laredo, Berlandier, S. W. Texas and adjacent Coahuila, Palmer, 

 nos. 556, 557, 558 (colh of 1880). 



Var. ARGOPHTLLU^r, Gray. Hood rauticous : leaves small, tomentose 

 upon both surfaces, canescent above, snowy white beneath. — Gray in 

 Wats. Proc. Am. Acad, xviii. 104 (1883 without description). — 

 Coahuila and Nuevo Leon, Palmer, no. 2068 (coll. of 1880). 



8. M. LEUCANTHUM, Torr. & Gray, FL ii. 271 (1842). — The com- 

 monest form of our southwestern States. Kansas, Hamilton County, 

 Hitchcock, no. 250 ; W. Texas, Lindheimer, no. 636, Peverchon, no. 

 1380*, Thurber, no. 128, Heller, no. 1632, Pope, Bigelow, Wislizenus ; 

 New Mexico, Thurber, no. 1105, Wooton, no. 117; Arizona, RothrocJc, 

 no. 327, Palmer, no. 608, Pringle, coll. of 1884; Chihuahua, Privgle. 

 This plant has of late been generally regarded as a mere form of 



