ORDER XXXVIII. ACERACEiE. 265 



with them, occasionally wanting. Stamens 8 — 12, distinct. 

 Anthers oblong, versatile or introrse. Torus discoid. Ovary 

 composed of 2 united carpels. Styles united. Stigmas separ- 

 ate. Fruit a samara, composed of 2 indehiscent carpels, each 

 1 -eel led, 1 or 2 seeded. Embryo curved, with foliaceous cotyl- 

 edons. Trees with opposite leaves. 



Genus I— A'CER. Moen. 8—1. 

 (From acer, hard or sharp, in allusion to the hardness of the wood.) 



Calyx 4 — 5-cleft. Petals 5 or wanting. Stamens 5 — 7 — 

 10. Leaves simple. 



1. A. Pexnsylvan'icum, (L.) A small tree, with smooth striped bark. 

 Leaves glabrous, sub-cordate, serrate, 3-lobed, lobes acuminate. Flow- 

 ers in nodding racemes, large. Petals obovate. — Yellowish-green. ^ . 

 May. Mountains. 10 — 15 feet; Striped Maple. Dogwood. 



2. A. monta'num, (Ait.) A small tree. Leaves sub-cordate, generally 

 5-lobed, serrate, pubescent beneath ; lobes acuminate. Racemes com- 

 pound, erect. Flowers small. Fruit reddish, glabrous, with slightly 

 spreading wings. — Greenish-yellow. April — May. Mountains. 8 — 12 ft. 



A. spicatv/m, Lam. 



3. A. sacciiari'num, (L.) A large tree, with compact, white wood, and 

 from the peculiar arrangement of its woody tissues often exhibits an 

 appearance distinguished by artists and mechanics by Bird's-eye Maple 

 Leases 3 — 5-lobed, acuminate, dentate, sub-cordate at the base. Flow- 

 ers in nearly sessile corymb?, with filiform long villous pedicels, pendu 

 lous. Petals wanting. Fruit glabrous. — Greenish-yellow. ^ . May. 

 Cool, damp places. Middle Geo. 50 — 80 ft. Sugar Maple. 



4. A. dasycak'pum, (Ehrh.) A large tree. Leaves palmate, deeply 

 5-lobed, acuminate, senate, and incised, pubescent underneath, almost 

 white. Floioers small in fascicles, with very short pedicels. Petals 

 wanting. Fruit yellowish, wings large, pubescent when young. — Pale 

 yellowish-purple. Feb. In river swamps, common. 50 — 10 feet. 



Soft Maple. 



5. A. ru'brum, (L.) A small tree. Leaves cordate, 3 — 5-lobed, ser- 

 rate, glaucous beneath, lobes acute, doubly serrate, terminal one lon- 

 gest. Flowers in small axillary fascicles. Petals linear or oblong, po- 

 lygamous. Stamens 5 — 8. Fruit glabrous, with slightly divergent 

 wings, reddish. — Bright red or purplish. ^ . Feb. In swamps, com- 

 mon. 20 — 50 feet. Scarlet Maple. Red Maple. Swamp Maple. 



6. A. negtjn'do, (L.) A middle-sized tree. Leaves pinnate, 3 — 5 

 leaflets ; leaflets petiolate-oval or ovate, unequally toothed toward the 

 apex. Flowers dioecious, in pendulous racemes. Pedicels of the stami- 

 nate flowers filiform. Petals none. Fruit oblong, with pale yellow, 

 obovate wings. — Yellowish-green. ^. May. Common on the banks 

 of streams. 30 — 50 ft. Ashed-leaved Maple. Box Elder. 



Order XXXIX.— HIPPOCASTANA'CE^E. D. C. 



Calyx composed of 5 united sepals, either campanulate or 

 tubular, 5-lobed or 5-toothed, with imbricate aestivation. Petal* 



12 



