Butler : The western American birches 425 



^2. Betula glandulifera (Regel) sp. nov. 



Betula piimila glandulifera Regel, Bull. Soc. Nat. Moscou 38 : 



410. 1865. 



A low shrub 1-2 m. high ; branchlets very slender, reddish 

 brown, shining, slightly glandular-resiniferous with long coarse 

 scattered hairs, never pubescent, becoming smooth and gray; leaf- 

 blades 2-5 cm. long, 1-3.5 *^^^- wide, obovate to suborbicular, 

 with mostly acute, sometimes obtuse or rounded apex and cuneate 

 base, often ovate on young shoots, smooth, thick, shining, dark 

 green, serrate to crenate -serrate, often doubly serrate, with broadly 

 triangular teeth 2-5 mm. broad at the base, strongly reticulated, 

 hairy on basal margin and along veins beneath when young, some- 

 times pubescent on young shoots, thickly covered beneath with 

 minute resin-dots; petioles 3-8 mm. long; fruiting aments 1.5-2 cm. 

 long, 3—5 mm. thick, erect, cylindrical ; bractlets puberulent, lobes 

 about equal in width, the middle obtuse or truncate, longer than 

 the ascending or slightly spreading rounded lateral ones ; samara 

 wings much narrower than the oval or ovate nutlet. [Figure 2.] 



This species is distinguished by the coarse hairs upon the 

 slightly resinous branchlets and the obovate, coarsely toothed 

 leaves, which are strongly resin-dotted beneath. It is more closely 

 related to several other forms than to Betula piunila^ an eastern 

 species not reaching the Rocky Mountain region, of which it 

 has been considered a variety. It ranges from Oregon and British 

 Columbia eastward to Michigan and Western Ontario. The spec- 

 imens from the Middle West have bractlets with somewhat nar- 

 rower lobes. 



3. Betula Hornei sp. nov. 



A shrub 1-2 m. high, glabrous ; twigs and branchlets dark 

 purplish-brown, glandular-resiniferous ; older stems with thin gray 

 easily removed coating; leaf-blades up to 4 cm. long and nearly 

 or quite as wide, thick, dark bronze-green, yellowish below, 

 broadly rhombic or ovate, with acute or obtuse apex and cordate 

 or subcuneate base, sometimes lobed, irregularly crenate- serrate, 

 often doubly serrate, with mostly coarse teeth, strongly reticulated, 

 with 4 or 5 pairs of veins impressed above and conspicuous below, 



resin-dotted ; 



0-15 mm. long, glabrous; 



fruiting aments about 15 mm. long, 8-iomm. thick, oval, glabrous, 

 the stalk about 10 mm. long; bractlets about 5 mm. long and 

 4 mm. wide, lobes about equal in Avidth, the middle lobe obtuse, 

 the lateral obliquely ovate or rhombic, acute above, ascending, 



