648 ORDER 120. BETULACE^E. 



dulous; buds rather acute. A small tree disseminated throughout the U. S., 

 25 30f in height. Its bark is remarkable for its fine, narrow, longitudinal di- 

 visions. Leaves about twice as long as wide. The fruit is similar in appearance 

 to hops, suspended from the ends of the branches, consisting of membranous, im- 

 bricated sacs (cups ?) containing each a flower. The wood is very white, hard 

 and strong, much used for levers, &c. Apr., May. 



6. CARPFNUS, L. HORNBEAM. (Celtic car, wood, and pino, the 

 head ; alluding to its use in making yokes for cattle.) $ Flowers in a 

 long, cylindric ament; cal. scale roundish, clliate ; sta. 8 14, slightly- 

 bearded at summit. ? Flowers in a loose ament ; scale large, oblong, 3- 

 lobed, 1 3-flowered ; cal. 6-toothed ; stig. 2 ; nut long, ovoid, fur- 

 rowed, 1-seeded. Small trees. Scales of the $ aments persistent and 

 becoming foliaccous. 



C- Americana L. Lvs. oblong-ovate, acuminate, unequally serrate ; scales of tho 

 fertile ament 3-parted, the middle segment much the- largest, oblique r with a 

 lateral tooth. A small tree (12 20f high), common in woods throughout the U. 

 S. The wood is very fine-grained, compact and white, covered with a light gray 

 or ash-colored bark. Leaves 2 4' long, as wide, petiolate. From the ends of 

 the branches hang the long, loose, pale green, leafy aments, consisting of alter- 

 nate pairs of enlarged scales, with a dark-colored nut at the base of each. Apr., 

 May. 



ORDER CXX. BETTJLACEJi BIRCHWORTS. 



Trees or shrubs with deciduous stipules. Bark separating into thin layers. Leaves 

 alternate, simple, with the veinlets running straight to the margin. Flowers mon- 

 oecious, amentaceous, mostly naked, 3 in tho axil of a 3-lobed bract. $ Stamens 

 definite, distinct. Anthers 2-celled. $ Ovary 2-celled, 2-ovuled, becoming in fruit 

 1-celled and 1-seeded (by abortion) membranous and indohiscent. Seed pendulous r 

 without albumen. Figs. 7 7, 90, 106, 111, 419, 420. 



Genera 2, species 65, chiefly natives of tho cool parts of tho northern hemisphere. Properties- 

 generally astringent. The birches arc often lino timber trees. 



I. BE'TULA, Tourn. BIRCH. (Betu is the Celtic name for the birch.) 

 $ Flowers in a cylindric ament ; bracts deeply 3-parted, peltate ; calyx 

 a scale ; stamens 4. $ Ament oblong-ovoid, scales trilobate ; calyx ; 

 ovaries 3 under each scale ; stigmas 2, filiform ; nut compressed, with 

 a membranous margin. Trees and shrubs, with the outer bark lam- 

 inated and horizontally fibrous, the inner aromatic. Branchlets dot- 

 ted. Lvs. ovate, serrate. Figs. 419, 420. 



* Trees with a yellowish bark, smoothish leaves, and short, erect, $ nmeuts No. 1 



* Trees with a reddish-brown bark and ovate-oblong, suberect, 9 aments Nos, 2, 3 



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



* Shrubs with brownish bark, roundish leaves and short, erect, ? aments Nos. 6, 1 



1 B. excelsa Ait YELLOW BIRCH. Lvs. ovate-elliptic, subacuminate ; sub- 

 cordate, coarsely, sharply, and doubly serrate, smooth when old, on short, downy 

 petioles ; fertile aments erect, ovoid-oblong ; lobes of the bracts subequal, acute, 

 diverging. A common forest tree, N. Eng. to Mich, and Can., arising in woods 

 to the height of 60 to 80C with a trunk 2 to 3f in diam., invested with a thin, 

 yellowish, silvery outer bark stripping off in transverse shreds. Barren aments 

 2 to 4' long, cylindric, clustered, and pendulous at the ends of tho branches ; 

 fertile 1' long, 6" diam. Apr., May. 



2 B. lenta L. BLACK BIRCH. SWEET BIRCH. MAHOGANY BIRCH. (Tig. 202.) 

 Lvs. cordate-ovate, acuminate, acutely, finely, and doubly serrate, veins beneath 

 and petioles hairy; fertile aments erect, oval-oblong, thick, obtuse, pedunculate; 

 ecales hairy, the lobes obtuse, subequal, diverging. This noble species is com- 

 mon in the Eastern and Middle {States, often exceeding 6 Of in height, with a 



