38G BETULACEAE (BIRCH FAMILY) 



papyracea, var. Tvickerm.) — Alpine regions and cold bogs, Lab. to Sask., s. to 

 n. N. E. and Minn. ((Jreeul.) 



-*- ■(- Wings nnrrov^ttr than or raniy as broad as the body of lite fruit., or want- 

 ing ; shrubs with dark scarcely paptry bark., subsessile or short-petioled 

 thickish or coriaceous small leaves., and narrowly ovoid or cylindric mostly 

 erect sessile or short-pedu)icled catkins. 



■H*- Young branchlets. pubescent with long soft hairs. 



7. B. pumila L. (Low or Swamp B.) Stems 0.5-3 m. high, erect or ascending, 

 not glandular ; young branches and lower face of young leaves mostly soft- 

 downy; (cavf's obova^tt., orbicular, or renifonn, l-o.o cm. long, not resiniferous, 

 pale beneath., veinlets on both faces ^finely reticulated ; fruiting catkins 0.7-3 cm. 

 long, 5-9 mm. thick. — Bogs, Lab. and Nfd. to Ont., s. to n. N. J., O., Ind., 111., 

 and Minn. (Eurasia.) 



Var. glandulifera Regel. Young branchlets and leaves resiniferous or glandu- 

 lar-dotted. — (Jnt. and Mich, to Minn, and Sask. 



++ ++ Young branchlets glabrous or at most minutely puberulent, conspicuously 



dotted with resinous wart-like glands. 



8. B. glandulosa Michx, (Dwarf B.) Stems erect or depressed, 0.3-2 m. 

 high, or when alpine procumi)ent ; leaves icedge-obovate. 0.5-3 cm. long, green 

 and glabrous both sidfs, slighlly reticulated; fruiting catkins 0.5-2.5 cm. long, 

 3-7 mm thick. — Arctic barrens, s. to mts. of N, B., Me., and N. H. ; L. 

 Superior, xVlinn., etc. (.\sia. ) Var. rotixdifolia (Spach) Regel. Very 

 dwarf ; leaves orbicular orreniform. — Arctic regions to mts. of Me. and N. H. 

 (Alaska ; A.sia. ) 



5. ALNUS [Tourn.] Hill. Alder 



Sterile catkins with 4 or 5 bractlets and 3 (rarely ^A flowers upon each short- 

 stalked shield-shaped scale ; each flower usually with a 3-5-parted calyx and 

 as many stamens ; filaments short and simple ; anthers 2-celled. Fertile catkins 

 ovoitl or ellipsoid ; the fleshy .scales each subtending 2 flowers and a group of 

 4 little scalelets adherent to the scales or bracts of the catkin, which are woody 

 in fruit, wedge-obovate, truncate, or 3-5-lol)ed. — Shrubs or small trees with 

 few-scaled leaf-buds and solitary or often racemose-clustered catkins. (The 

 ancient Latin name. ) 



* Flowers developed with the leaves ; the sterile catkins from naked buds formed 



the preceding season; the fertile from scale-covered buds; fruit with a 

 conspicuous thin wing. 



1. A. crispa (Ait.) Pursh. (Green or Mountain A.) Shrub with young 

 branches and peduncles sparingly puberulent or glabrat^ ; leaves round-oval, 

 ovate or slightly heart-shaped, in maturity 3-6 cm. long, glutinous and smooth, 

 or slightly pubescent on the principal veins beneath., irregularly serrulate or 

 biserrulate with very fine and sharp clo.sely set teeth, the margins often puck- 

 ered ; fertile catkins slender-stalked, looselj^ racemose, in maturity 1-1.5 cm. 

 long. {A. viridis Man. ed. 6, in part, not DC. ; A. Alnobctula Am. auth., in 

 part, not K. Koch.) — Cool shores and mts.. Lab. to N. B. ; Mt. Katahdin, Me. ; 

 Mt. Washington, N. H. ; Whiteface Mt., N. Y. ; and on the mts. to N. C. 



2. A. m611is Fernald. (Downy Green A.) Shrul) or small tree; young 

 branches and peduncles permanently soft-pubescent ; leaves permnnently covered 

 beneath with dense soft hairs, in maturity 4.5-11 cm. long ; mature fertile catkins 

 1.2-2 cm. long. (A. viridis Man. ed. 0, in ]iart, not DC. ; A. Alnobetuln Am. 

 auth., HI part, not K. Koch.) — Damp thickets and expo.sed rocky banks, s. Nfd. 

 to L. Winnipeg, s. to s. Me. and N. H., w. Mass., N. Y., and L. Superior. — 

 (Ordinarily distinct, but possibly an extreme variation of A. crispa. 



* * Flowers developed in earliest spring before the leaven ; the catkins all from ' 



naked buds formed the preceding season ; fruit vnngless or ivith a narroic 

 coriaceous margin. 



