fruit 



»f the mature 



202 FAGACEAE 



white and punctate beneath, with many lateral veins and obsolete reticulations, 

 usually entire or with a few spinulose-tipped teeth; those of the sterile shoots 

 almost orbicular or round-ovate in outline, coarsely and deeply dentate with 

 spuiose-tipped teeth; cup hemispheric, 10-14 mm. in diameter; scales ovate, 

 with brown acute tips; acorn ovoid, about 15 mm. long. Mountains: N M — 

 Utah — -Ariz. — Nev. Son. 



17. Q. turbinella Greene. A shrub 1-3 m. high; young branchlets covered 

 with a white stellate-pubescence and when young with fulvous tomentum; leaf- 

 blades oblong, elliptic, oval or rarely ovate, 1-3 cm. long, acute at the apex, 

 usually sinuate-dentate with spinulose-tipped teeth, when unfolding covered 

 Vith a fulvous tomentum, light bluish green and shining above, strongly reticulate, 

 fulvous, stellate-pubescent beneath; cup 8-10 mm. in diameter; scales deltoid- 

 ovate, obtuse, moderately corky-thickened; acorn 15-20 mm. long, 8 mm. in 

 diameter. Dry hills: CaUf.— Utah— Ariz.; Sonora and L. Calif. Son. Ap-My. 



Family 32. BETULACEAE. Birch Family. 



Monoecious trees or shrubs, with simple alternate leaves. Staminate 

 flowers in long drooping aments, each bract subtending 2 or 3 flowers; calyx 

 present. Pistillate flowers also in aments, but the aments seldom drooping, 

 without calyx; pistils 2 or 3 at the base of each bract. Fruiting aments 

 cone-like; fruit small nuts or samaras; sssd solitary. 



■^^^Hof tlie mature pistillate araents membranous, in ours 3-lobed, deciduous with the 



pistillate ameats thickened and woody, persistent. 2." Alxus. ' 



1. BETULA (Tourn.) L. Birch. 



Shrubs or trees, with resinous aromatic bark; branchlets with transverse 

 lenticels. btammate aments slender, pendulous; calyx irregularly 2- or 4-lobed; 

 stamens 2, inserted at the base of the calyx; filaments very short, branched at the 

 apex,- anther-sacs separate. Pistillate aments erect or drooping, oblong or 

 cyhndric; bracts elongate, in ours 3-lobed, 3-flowered, accrescent, deciduous, 

 i^ruit smaU, samara-like or nut-like, flat; outer seed-coat thin, produced into a 

 wing or margin ; seeds sohtary, pendulous . 



Bark separatmg Into layers or sheets, the very thin outer layer peeUng into smaU shreds; 



Bark chalky white to silvery gray. 



Leaves broadly ovate, with acute apex, mostly subcordate base, and spreading 

 teeth; twigs mostly glabrous; middle lobe of the bractlets acute, sUghtly longer 

 than the rounded lateral ones. 1 b subcordata 



Leaves narrowly ovate, with long-acute or acuminate apex, rounded or cunea'te 

 base, and teeth directed forward; twigs pubescent; middle lobe of the bractlets 

 narrow, rounded at the apex, about twice as long as the acute or obtuse lateral 



Bark yeUowish or reddish brown, often very dark; twigs very glandular ^"P^''*-'^''"- 

 Leaves ovate, very thin dark green, acute at the apex, irregularly doubly-serrate. 



with long-pointed, slender teeth. 3 B occidentalis 



Leaves deltoid or ovate, thick, bronze-green, long-acuminate at the apex, coarsely 

 and more regularly serrate. 4 n alniknWn 



Bark not separating into layers; outer bark not peeling into shreds ' "'"*'^"""- 

 Samara-wing broader than the body. 



Tw^s and branchlets glandular-resiniferous, not hairy. 



Lateral lobes of the bractlets spreadhig, obliquely ovate, auricled at the base; 



Leaves veiy thin; fruiting aments narrowly cylindric. elongate, less than 

 1 cm. tluck; lateral lobes of the bractlets obtuse or rounded: claw much 

 shorter than the middle lobe. 5 b Piperi 



Lea v^ thick; fruiting aments broadly cylindric, stout, more than 'l cm. 

 ^55,' lateral lobes of the bractlets mostly acute; claw as long as the 

 miaaie lODe. g ^ utahensis 



Lateral lobes of the bractlets ascending, obUquely rhombic, not auricled at the 



base; shrubs or trees. 



Shrubs or small shrub-like trees; bark shining, dark red-brown, smooth; 

 leaves broadly ovate usually less than 4 cm. long, coarsely and irregu- 

 larly serrate thui. dark green, obtuse or acute at the apex, fnostly 

 rounded at the base; twigs densely glandular-resiniferous 



7. B. fontinalis. 



