ACEBACE^B 681 



XXXV. ACERACE^. 



Trees or rarely shrubs, with limpid juice, terete branches, scaly buds, their inner scales 

 accrescent and marking the base of the branchlets with ring-like scars, and fibrous roots. 

 Leaves opposite, or on vigorous shoots rarely in whorls of 3, long-petiolate, simple, palmately 

 3-7-lobed and nerved or pinnately 3-7-foliolulate, usually without stipules, deciduous, in 

 falling leaving small U-shaped narrow scars showing the ends of 3 equidistant fibro-vas- 

 cular bundles. Flowers regular, direciously or monoeciously polygamous, rarely perfect or 

 dioecious, in fascicles produced from separate lateral buds appearing in early spring before 

 the leaves or in terminal and lateral racemes or panicles appearing with or later than the 

 leaves; bracts minute, caducous; calyx colored, generally o-parted, the lobes imbricated in 

 the bud; petals usually 5, imbricated in the bud, or 0; disk annular, fleshy, more or less 

 lobed, with a free margin; stamens 4-10, usually 7 or 8, inserted on the summit or inside of 

 the disk, hypogynous; filaments distinct, filiform, commonly exserted in the staminate, 

 shorter and generally abortive in the pistillate flower; anthers oblong or linear, attached 

 at the base, introrse, 2-celled, the cells opening longitudinally; ovary 2-lobed, 2-celled, com- 

 pressed contrary to the dissepiment, wing-margined on the back; styles 2, inserted between 

 the lobes of the ovary, connate below and divided into 2 linear branches stigmatose on their 

 inner surface; ovules 2 in each cell, collateral, rarely superposed, ascending, attached by 

 their broad base to the inner angle of the cell, anatropous or amphitropous ; micropyle 

 inferior. Fruit composed of 2 samaras separable from a small persistent axis, the nut-like 

 carpels compressed laterally, produced on the back into a large chartaceous or coriaceous 

 reticulated obovate wing thickened on the lower margin. Seed solitary by abortion, or 

 rarely 2 in each cell, ovoid, compressed, irregularly 3-angled, ascending obliquely, without 

 albumen; seed-coat membranaceous, the inner coat often fleshy; embryo conduplicate; 

 cotyledons thin, foliaceous or coriaceous, irregularly plicate, incumbent or accumbent on 

 the elongated descending radicle turned toward the hilum. 



A family of two genera, one widely distributed, the other, Dipteronia, distinguished 

 by the broad wings encircling the mature carpels, and represented by a single Chinese 

 species. 



1. ACER L. Maple. 



Characters of the family. 



Acer with sixty or seventy species is widely distributed over the northern hemisphere, 

 with a single species extending south of the equator to the mountains of Java. Acer pro- 

 duces light close-grained moderately hard wood valued for the interior finish of houses and 

 in turnery. The bark is astringent, and the limpid sweet sap of some of the American 

 species is manufactured into sugar. 



Acer is the classical name of the Maple-tree. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 



Leaves simple, usually palmately lobed (sometimes 3-foliolate in 1, 3-lobed at apex in ) 

 Flowers appearing with or after the leaves. 

 Flowers with petals; sepals distinct. 

 Inflorescence corymbose. 



Flowers in terminal drooping corymbs. 



Leaves 3-lobed or parted. 1. A. glabrum (B, F, G). 



Leaves palmately 3-5-lobed. 2. A. circinatum (B, G). 



Inflorescence racemose. 



Flowers in dense erect racemes. . A. spicatum (A). 



Flowers in drooping racemes. 



Ovary and young fruit glabrous; leaves 3-lobed at apex. 



4. pennsylvanictun (A). 

 Ovary and young fruit hairy ; leaves deeply 5-lobed. 5 . A. macrophyllum (G) . 



