Distribution. Florida, upper Matecombe and Old Rhodes Keys, and eastward on the southern keys, and on the Everglade Keys, Dade County; on the Bahama Islands, and widely distributed through the West Indies to Venezuela.
XXXV. ACERACEÆ.
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-vascular bundles. Flowers regular, diœciously or monœciously polygamous, rarely perfect or diœcious, 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 5-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, compressed 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 produces 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 4). 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.3. [A. spicatum] (A). Flowers in drooping racemes. Ovary and young fruit glabrous; leaves 3-lobed at apex.4. [A. pennsylvanicum] (A). Ovary and young fruit hairy; leaves deeply 5-lobed.5. [A. macrophyllum] (G). Flowers without petals; sepals united; inflorescence corymbose; pedicels long, pendulous, mostly hairy. Leaves pale or glaucescent, or green and glabrous beneath. Leaves green or pale beneath, glabrous or in one form villose-pubescent on the under side of the veins and on the petioles.6. [A. saccharum] (A, C). Leaves pale and pubescent, rarely glabrous beneath, their lobes usually short and obtuse or acuminate. Lobes of the leaves only slightly lobed or entire; bark of young trees smooth and pale.7. [A. floridanum] (C). Lobes of the leaves distinctly lobulate; bark of young trees dark brown and scaly.8. [A. grandidentatum] (F, H). Leaves green and pubescent, rarely glabrous beneath. Leaves hirsute-pubescent beneath and on the petioles, the lobes entire or lobulate, the basal sinus often closed by the lower lobes; bark dark and furrowed.9. [A. nigrum] (A). Leaves pilose-pubescent, rarely glabrous beneath, the lobes slightly lobulate, the basal sinus open; petioles glabrous; bark pale and smooth.10. [A. leucoderme] (C). Flowers appearing before the leaves in dense lateral clusters from separate buds; leaves 5-lobed (3-lobed in varieties of 12); fruit ripening in May or June. Flowers sessile or short-stalked, without petals; ovary and young fruit tomentose.11. [A. saccharinum] Flowers on long pedicels, with petals; ovary and young fruit glabrous.12. [A. rubrum] Leaves 3—7-foliolate; flowers diœcious, without petals.13. [A. Negundo] (A, B, C, F, G, H).