FERNALD. — ALNUS. 27 



de Cuyiunocalco, alt. 2155 m., Apr. 24, 1895 (Z. C. Smith, no. 495). 

 Said to be a large tree. 



* * Mature strobiles less than 2 cm. long (exceptional plants of .1. obloiH/ifolia 

 and A. ijlahrata may be looked for here). 



•t- Mature leaves ferrugineous-velutinous beneath. 



A. ferruginea, IIBK. Uraiiches brown, the younger parts more 

 or less pubescent: buds very pubescent: leaves ovate, acuminate at tip, 

 rounded or narrowed at base, coarsely and doubly serrate, 0.5 to 1.5 

 dm. long, 3.5 to 8 cm. broad, dull green and minutely pilose above ; 

 petiole thickish, 1 to 2 cm. long : peduncles villous or glabrate, the 

 staminate aments becoming 1.5 dm. long: the dark brown short-oblong 

 strobiles subsessile or short-stalked, in maturity 1.5 to 1.9 cm. long, about 

 1 cm. thick: nutlets cuneate-obovate, 3 mm. long, 2 mm. wide, with nar- 

 rower coriaceous wings. — HBK. 1. c. 21. A. acuminata, h ferru- 

 ginea, Regel, 1. c. 184; Hemsl. I.e. 1G5. — Described from Colombia. 

 Extending into Central America and Southern Mexico. Chiapas 

 (^Ghiesbreght, no. IGO) : Guatemala, Coban, Alta Verapaz, alt. 1488 m., 

 Feb. 1886 {H. von Tuerckheim in Exsicc. J. D. Smith, no. 351). 



■i-t- Mature leaves merely pilose on the nerves beneath. 



A. jorullensis, HBK. Branches reddish brown, smooth, the 

 younger parts pul)erulent or glabrate : buds pruinose : leaves oblong or 

 oblong-obovate, thick, mostly 7 to 13 cm. long, 2.5 to 5.5 cm. wide, 

 rounded or acute at tip, subcuneate or rounded at the subentire base, 

 creimte-serrate toward the tip, glaucous and sublucid above, brownish 

 beneath and closely pruinose with glandular or waxy atoms, the prom- 

 inent nerves more or less pilose; petioles thickish, 3 to 10 mm. long, 

 pubescent or glabrate : peduncles thick, pruinose or glabrate ; staminate 

 aments 3 or 4, becoming 6 cm. long ; the reddish-brown strobiles 3 or 4, 

 sessile or subsessile, oblong-ovoid, 1 to 1.8 cm. long, barely 1 cm. thick: 

 nutlets cuneate-obovate to suborbicular, 2.5 mm. long, 2 to 2.5 mm. 

 broad, with narrow membranaceous wings. — HBK. 1. c. 20; Regel, 

 I.e. ; Hemsl. 1. c. IGG, in part. A. acuminata, Sargent, 1. c. in part, not 

 HBK. Sierra IMadre of Central and West-Central Mexico. Described 

 from Volcan de Jorullo, Michoacau. Miciioacax, mountains near 

 Patzcuaro, Dec. 21, 1891 {C. G. Pringle, no. 5057); Sierra Madre, 

 without locality {Seemann) : Mexico, foothill of Mt. Ixtaccihautl, Jan. 

 5, 1899 (C. C. Beam, no. 130). 



Var. exigua, u. var. Leaves short-oblong, 2 to 4 cm. long, 1 to 



