GREENMAN. — NEW ANGIOSPERMS FROM MEXICO. 115 



BiDENS TERETiCArLis, DC, var. sordida. Leaves mostly simple 

 and undivided, rarely deeply 3-parted, sordid-pubescent upon both sur- 

 faces more densely so beneath : outer scales of the involucre rusty 

 tomentose. — Costa Rica. Thai des rio Segando, Hoffmann, no. 383 

 (hb. Gr.) ; forets de la Mala Via au Copey, April, 1898, Ad. Tonduz, 

 no. 12,284 (hb. Gr., and hb. Inst. Phys.-Geog. Cost. Ri.). 



Arnicastrum, n. gen. of Compositce {HelenoidecB) . Heads heter- 

 ogamous, many-flowered. Involucre campanulate ; bracts 2-3-seriate, 

 the outer herbaceous. Receptacle convex, naked. Ray-flowers yellow, 

 ligulate, 2-3-dentate, fertile, epappose ; mature achenes numerously 

 ribbed. Disk-flowers with a rather slender tube dilated above into 

 an equally 5-toothed limb : pappus of numerous somewhat unequal 

 barbellate bristles : achenes slightly compressed, 4-angled, many-ribbed. 

 Herbaceous perennia,ls with opposite leaves and rather large heads. 



A. glandulosum. Stems erect, 3 to 5 dm. high, mostly branched 

 from the base, striate, hisj^idulous-pubescent, and above especially on the 

 usually long peduncles bearing loug-stipitate purplish glandular hairs : 

 leaves sessile, subamplexicaul, 3-o-nerved from the base, narrowly lan- 

 ceolate, 2 to 8 cm. long, 3 to 15 mm. broad, entire or si^aringly denticu- 

 late, hispidulous-pubescent on both surfaces : heads about 1 cm. high, 

 including the rays 3 to 4.5 cm. in diameter ; outer involucral scales 

 oblong or oblong-ovate, 10 to 12 mm. long, 5 to 8 mm. broad, obtuse, 

 entire, hirtellous-pubescent on the outer surface ; the inner scales mostly 

 longer, sometimes acuminate, membranous: ray-flowers about 10; tube 

 2 to 3 mm. long, externally pubescent; rays elliptic-oblong, 1.5 cm. 

 long, 6 mm. broad : disk-flowers numerous : pappus-bristles unequal, the 

 longer equalling or exceeding the tube of the corolla : achenes hirtel- 

 lous-puberulent above, many-ribbed. — Mexico. State of Chihuahua : 

 Sierra Madre, 21 June, 29 July, 1899, E. W. Nelson, no. 6102 (hb. Gr., 

 and hb. U. S. Nat. Mus.) ; Sierra Madre, near Colonia Garcia, altitude 

 2450 m., 26 July, 1899, Townsend ^ Barber,-no. 169 (hb. Gr.). 



Var. vestitum. Outer scales of the involucre 7 to 9 mm. Ion it, and 

 closely covered with purplish glandular hairs ; otherwise like the species 

 proper. — Mexico. State of Durango : 48 km. north of Guanacevi, 

 altitude 2450 to 2775 m., 18 August, 1898, E. W. Nelson, no. 4778 

 (hb. Gr., and hb. U. S. Nat. Mus.), In general habit Arnicastrum glan- 

 dulosum, and the variety vestitum resemble certain species of Arnica more 

 particularly in the opposite leaves and the rather long internodes. In 

 the technical characters of the head, however, they seem to have their 

 nearest affinity with Jaumea, Bceria and Whitneya. 



