508 ORDER CXT. AMENTACEJS. 



Perianth of the 6terile florets reniforni, acuminate, 1-flowered. Fila- 

 ments 3. Anthers 6. Nuts forming a round bur. — ^. April — May. 

 Woods and fields. 2 — 1 feet. Sweet-fern 



Sub-order III.— BETULA'CE^E. (Birch Tribe.) 



Flowers with bracts. Fruit membranous, 2-celled, forming 

 a sort of cone. 



Genus V.— BET'ULA. L. 19—12. 

 (From bet u, its Celtic name.) 



Monoecious. Ament cylindrical. Sterile florets, with the 

 scales peltate. Stamens 10 — 12. Fertile florets; scales im- 

 perfectly 3-lobed, 3-fiowered. Styles 2. Nuts compressed, 

 with a membranaceous margin. 



1. B. ni'gra, (L.) A tree, covered with smooth scaly bark, with long 

 flexible branches. Leaves rhombic-ovate, doubly serrate, acute, pubes- 

 cent beneath, entire at the base, on short petioles. Fertile ament ovate. 

 Scales villous, with equal and linear segments. — *> . May. Banks of 

 streams. 30—40 feet. Red Birch. 



2. B. len'ta, (L.) A large tree, with long slender branches, which 

 are spotted with white when young, with a fragrant and aromatic bark. 

 Leaves cordate, ovate, acuminate, sharply serrate, nerves and petioles 

 hairy ; scales of the ament smooth. — ^. May. Mountains. 70 — 80 ft. 



Cherry Birch. Black Birch. 



Genus VI.— AL'NUS. Tourn. 19—12. 

 (From al, near, and Ian, the edge of the river.) 



Monoecious. Sterile florets ; ament long, cylindrical ; scales 

 3-lobed, 3-flowered ; perianth 4-parted. Stamens 4. Fertile 

 florets ; ament ovate ; scales 2-flowered ; perianth none. Styles 

 2. Seed compressed, ovate, naked. 



1. A. serrula'ta, (Ait.) A middle-sized shrub, with numerous irreg- 

 ular branches. Leaves alternate, obovate, acuminate, with the veins 

 on the under surface hairy, doubly serrate. Sterile flowers in long 

 pendulous arnents. — ^. February. Along water-courses. Very com- 

 mon. 8 — 12 feet. 



Genus VII.— CARPI'NUS. L. 19—12. 

 (From car, wood, and pinda, head.) 



Monoecious. Sterile florets ; ament long, cylindrical ; scales 

 ciliate at the base. Stamens 8 — 14, somewhat bearded at the 

 top. Fertile florets ; ament imbricate ; scales leafy, 2-flowered. 

 Stigmas 2. Nut long, ovate, silicate, 1-seeded. 



1. C. America'na, (Mich.) A small tree. Leaves oblong-ovate, acu- 

 minate, unequally serrate. Scales 3-parted, the middle segment oblique, 

 toothed on one side. Scales of the fertile florets large, foliaceous. — ^ . 

 Mav. In woods. 15 — 20 feet, Iron-xvood. Hornbeam. 





