308 ORDEB 124.-MYRICACE.E. 



1. BETULA, Tourn. BIRCH. $ Fls. in clustered, drooping, slender 

 aments, bracts peltate, deeply 3-parted. Calyx a scale, sta. 4. ? Amenta 

 oblong-ovoid, bracts 3-lobed, 3-flowered. Calyx 0. Ovary tipped with 2 

 styles. Nut flattened, winged. *> b Buds sessile. Flowers yellow, pre- 

 cocious, in Spring. Figs. 163-4, 437. 



* Trees with a yellowish bark, smoothish leaves, and short, erect, ? aments No. 1 



* Trees with a reddish-brown bark and ovate-oblong, euberect, ? aments Nos. 2, 3 



* Trees with a white bark, long-stalked leaves, and drooping ? aments Nos. 4, 5 



* Shrubs with brownish bark, roundish leaves, and short, erect, ? aments Nos. 6, 7 



J B. 1 it tea MX./. Yellow B. A forest tree 40 80f, known at sight by its silver-yel- 

 low bark ; leaves ovate, deeply and doubly serrate ; $ aments 2 4', drooping, the ? 

 ovoid-oblong, 1', erect. Can. to N. Car. (B. excelsa C-B. not of Ait. f) 



2 B. leiita L. Black, Sweet, or Cherry B. A noble tree, about 60f ; Ivs. cordate-oval, 



acuminate, sharply serrulate ; $ aments 3 4', ? aments erect, pedunculate, much 

 shorter. Woods, Can. to Ga. Timber rose-colored. Cambium ( 418) sweet and spicy. 



3 B. nigra Ait. Red B. Tree 30 50f, the bark loose and torn ; leaves rhomb-ovate, 



acute both ends, repand and serrulate, small, petioles hairy ; 3 aments 2 3', droop- 

 ing, 9 oval, sessile, erect, 6". Swamps, Mass, to Fla. Twigs very slender. 



4 B. popnlifolia Ait. White B. Tree 30 40f, trunk white, twigs brown ; leaves 



deltoid (Fig. 307), lobed and serrulate, acuminate. Thickets, Me. to Pa. 



5 B. papyracea Ait. Paper, or Canoe B. Tree 50 70f. trunk white, branches brown ; 



Ivs. ovate, acuminate, doubly serrate ; ? aments 1' long. Mt. woods. Can. to Pa. 

 /3. minor. Shrub 6 9f, with smaller and merely acute leaves. White Mountains. 



6 B. pumila L. Dwarf B. Shrub 2 7f, branches (not glandular) and young leaves 



downy ; Ivs. rounded to obovate, serrate, 6 16". Swamps, Ct. to Pa. (Prof. Porter). 



7 B. glandulosa MX. Shrub 1 4f, upright, branches glabrous, dotted with wart- 



like glands leaves round-obovate, glabrous, crenate, 9". Mts., N. and N-W. 

 ft. rotundi folia. Shrublet prostrate, 612' ; Ivs. orbic. White Mts. (B. nana C-B.) 



2. ALNUS, Tourn. ALDER. Flowers in cylindric, drooping aments, 

 bracts peltate, with 5 scales and several flowers beneath. Calyx ^-parted, 

 sta. 4, anth. 2-celled. ? Aments ovoid, bracts cuneate, truncate, thick, 

 2-flowered. Calyx of 4 scales, persistent. 3 3 Buds peduncled. 



* Fls. developed before the Ivs. in early Spring. Fruit almost wingless Nos. 1, 2 



* Fls. developed with or after the leaves. Fruit winged, No. 3, wingless, No. 4 



1 A. I nt a 11.1 Willd. Speckled, or Black A. Stems 8 20f ; leaves obtuse at base, broad 



oval or ovate, sharp-serrate and some lobed, glaucous-downy beneath ; stipules lance- 

 oblong. Thickets by streams, N. Eng. to Wis. and Can. 



2 A. sermlata Ait. Smooth A. Stems in clumps, straightish, 10 15f ; Ivs. obovate, 



pointed, doubly serrulate, smooth ; stipules elliptical, obtuse. Swamps. 



3 A. viridis DC. Mountain. A. Shrub 3 4f; Ivs. oval, acute, clammy: slip, broad- 



ovate ; fertile aments on long stalks, oval. Streams in mountains, northward. 



4 A. niaritima Muhl. Tree 20f ; leaves glabrous, ovate to obovate, cuneate, serru- 



late ; fertile aments ovoid-oblong, V. River banks, Del., and S. 



ORDER CXXIV. MYRICACE^E. GALEWORTS. 



Shrubs with alternate, resinous-dotted, often fragrant leaves, with the 

 flowers monoscious or dkecious, both kinds in scaly aments, and destitute 

 of corolla or calyx. $ Stamens 2 8. ? Ovary 1-celled, with 1 erect ovule. 

 SPiff, filiform. Fr. dry or drupaceous, indehiscent. Seed with no albumen. 



