446 ACEKACE^E. 



a'' Leaves deciduous, thinnish ; nutlets ribbed ; leaves 



Small, obovate to oblanceolate-oblong, crenate I. decidua. 



Large, ovate to oblong and lanceolate, serrate I. monticola. 



For species sec pii. Sl.i-3.il. 



STAFF-TREE FAMILY. CELASTRACE^ Lindl. 



Trees, shrubs and climbing vines of about three hundred fifty species of tropical and 



temperate regions and grouped in forty genera. Four genera are represented among the trees 



of the United States, mainly southern. 



Leaves simple and with stipules small and caducous or none. Flowers regular, generally 

 perfect, in axillary clusters and mostly with jointed pedicels; calyx 4-.5-lobed or parted, imbri- 

 cated in the bud, persistent; petals 4-5. spreading, imbricated in the bud: stamens 4-."i, inserted 

 on the disk with 2-celled introrse anthers lungitudiiially dchisciMit ; ovary 2-.")-celled with 1 or 

 2 anatropous ovules in each cell (6 siih-hurizontal in ('(inotiu). Fruit a fleshy 2-4-celled 

 dehiscent capsule or drupe; seed furnished with a colored aril, containing copious albumen 

 and foliaceous cotyledons. 



THE WAHOO OR BURNING BUSH. Genus EUONYMUS L. 



Small trees and shrubs of about fifty species mainly of the northern hemisphere and most 

 numerous in southern Asia and Japan. Four species of which one is arborescent are natives 

 of the United States. 



Leaves opposite, petiolate. entire or serrate: stipules caducous. Flo)cers generally per- 

 fect, in few-flowered cymes, from the axils of the lower leaves of the season, greenish or 

 purple: calyx 4-.')-lobed ; petals of same number, spreading and inserted beneath the thick 

 4-lobed disk ; stamens as many as the petals, alternate with them and inserted on the disk ; 

 filaments very short : anthers with 2 cells, spreading below : ovary 4-celled with short style or 

 none and depressed stigma ; ovules usually 2 in each cell. Fniil a 4-lobed and 4-celled capsule, 

 fleshy, smooth (in the American species) or winged; longitudinally dehiscent; seeds 1 or 2 

 in each cell, ascending and sui-rounded by a red aril. 



The name is the classical Greek name of a European species. 

 For species see pp. 322-323. 



MAPLE FAMILY. ACERACE^ St. Hil. 



Trees and a few shrubs with generally watery and saccharine sap and of wide distribution. 



It consists of two genera, Acer and Dipteronia, the former largely represented in America and 



the latter a genus of a single species in China. 



Leaves deciduous, opposite, long-petiolate, simple and palmately lobed or pinnate, usually 

 without stipules ; winter-buds scaly, the innermost scales accrescent. Flowers regular, poly- 

 gamous or dioecious, in axillary or terminal fascicles, cymes or racemes : calyx generally 

 5-parted, imbricated in the bud ; petals of same number or none ; disk thick, annular, lobed ; 

 stamens 4-12, usually 7-8, hypogenous with anthers 2-celled. introrse. the cells opening longi- 

 tudinally ; ovary 2-lobed, 2-celled, compressed, wing-margined ; styles 2. inserted between the 

 lobes and stigmatose on their inner surfaces ; ovules 2 in each cell, anatropous or amphitropous, 

 attached to inner angle. Fruit a pair of long-winged and usually 1-seeded samaras joined at 

 base ; wings papery, thickened on the outer margin ; seed usually solitary, compressed, ascend- 

 ing, without albumen ; cotyledons thin, folded. 



THE MAPLES. Genus ACER L. 



The genus consists of about seventy-five species widely distributed over the northern 

 hemisphere, only one species in Sumatra nnd .Java extending south of the equator. 



About thirteen species are represented in North America most of them having sweet sap, 

 from which sugar can be made, and several producing valuable lumber. 



Acer is the classical name of the Maple-tree. 



KEY TO THE SPECIES. 



a Leaves simple and palmately veined and lobed; flowers appearing 

 b After the leaves from terminal buds : fruit ripening in autumn 

 c Without petals, in long-pedicelled tassel-like corymbs ; leaves thick 



Pale beneath, glabrous, nearly flat and lobes coarsely undulate-dentate. 



A. Saccharum. 

 Green beneath ; concave and pubescent below ; lobes undulate or entire. 



A. nigrum. 

 c' With petals ; flowers in 



Erect racemes; leaves coarsely serrate-dentate A. spicatum. 



Drooping racemes; leaves finely and often doubly serrate. A. Pennsylvanicum. 



