314 DICOTYLEDONOUS, 



the sterile florets, reniform, acuminate,'l-flowered. Filaments 3. Anthers 6. 

 Nuts forming a round burr. Sweet fern, 



h April— May. Woods and fields. 2-4 tt. 



Sub-Order III. BETULINE^. 



Genus V. BETULA.^ 



Monoecious. Ament cylindrical. Sterile florets with the 

 scales peltate. Stamens 10-12. Fertile florets. Scales 

 imperfectly S-lobed, S-flowered. Styles 2. Nuts compressed, 

 with a membranaceous margin. 



1 B Nigra. A tree, covered with smooth scaly bark, with long flexible 

 branches. Leaves rhombic-ovate, doubly serrate, acute, pubescent beneath, 

 entire at the base, on short petioles. Fertile ament, ovate. Scales \alIou3, 

 with equal and linear segments. lied Birch. 



Iz May. Banks of streams. 30-40 ft. 



2 B Lenta. 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 



h May. Mountains. 70-80 ft. 



Genus VI. ALNUS. 



Monoecious. Sterile florets ; ament long, cylindrical. — 

 Scales 34obed, 3-flowered. Perianth 4-parted. Stamens 4, 

 Fertile florets ; ament ovate. Scales 2-flowered. Perianth 

 none. Styles 2. Seed compressed, ovate, naked. 



1 A. Serrulata. A middle sized shrub, with numerous irregular branches. 

 Leaves alternate, obovate, acuminate, with the veins on the under surface 

 hairy, doubly serrate. Sterile flowers in long pendulous aments. 

 T^ February. Along water courses. Very common. 8-12 ft. 



Genus VII. CARPINUS. 



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. iVwHong, ovate, sulcate, l-seedede 



1 C Americana. A small tree. Leaves oblong-ovate, acuminate, une- 

 qually serrate. Scales 3-parted, the middle segment oblique, toothed on one 

 side. Scales of the fertile florets large, foliaceous. Horn hean, 



}2 May. Woods. 15-20 ft. 



Genus VIII. OSTRYA. 



Monoecious. Sterile florets ; ament cylindrical. Scales 

 1-flowered. Filaments hra.nched. Fertile florets , ament na- 

 ked. Capsules inflated, imbricate, 1-seeded at the base. 



1 O ViRGiNicA. A small tree, with very compact, hard wood. Leaves 

 OTate-oblong, cordate at the base, alternate unequally serrate. Ament oblong- 

 ovate, erect, with inflated capsules, 1-seeded. Iron-vtood. 

 \l May. Woods. 20-30 ft. 



