Distribution. Rich soil, by streams or along the borders of the forest; valley of the lower Savannah River, near Savannah, Chatham County, and along the Wittlocoochee River, Lowndes County, Georgia, to central and western Florida; through Alabama; in southern and central Mississippi, and through Louisiana to eastern Texas (Beaumont, Jefferson County, and Fletcher, Harding County), and southern Arkansas; generally distributed and most abundant in Louisiana; probably of its largest size on the bluffs of the Alabama River in Dallas County, Alabama.
XXI. PLATANACEÆ.
Trees, with watery juice, thick deeply furrowed scaly bark exfoliating from the branches and young trunks in large thin plates, terete zigzag pithy branchlets prolonged by an upper axillary bud, and fibrous roots. Winter-buds axillary, conic, large, smooth, and lustrous, nearly surrounded at base by the narrow leaf-scars displaying a row of conspicuous dark fibro-vascular bundle-scars, covered by 3 deciduous scales, the 2 inner accrescent, strap-shaped, rounded at apex at maturity, marking in falling the base of the branchlet with narrow ring-like scars, the outer scale surrounding the bud and splitting longitudinally with its expansion, the second light green, covered by a gummy fragrant secretion and usually inclosing a bud in its axil, the third coated with long rufous hairs. Leaves longitudinally plicate in vernation, alternate, broadly ovate, cordate, truncate, or cuneate and decurrent on the petiole at base, more or less acutely 3—7-lobed, and occasionally furnished with a more or less enlarged basal lobe, the lobes entire, dentate with minute remote callous teeth, or coarsely sinuate-toothed, penniveined, the veins arcuate and united near the margins and connected by inconspicuous reticulate veinlets, clothed while young like the petioles, stipules, and young branchlets with caducous stellate sharp-pointed branching hairs, pale on the lower and rufous on the upper surface, long-petiolate; turning brown and withering in the autumn before falling; petioles abruptly enlarged at base and inclosing the buds; stipules membranaceous, laterally united below into a short tube surrounding the branchlet above the insertion of their leaf, acute, more or less free above, dentate or entire, thin and scarious on flowering shoots, broad and leaf-like on vigorous sterile branchlets, caducous, marking the branchlet in falling with narrow ring-like scars. Flowers minute, appearing with the unfolding of the leaves in dense unisexual pedunculate solitary or spicate heads, the staminate and pistillate heads on separate peduncles or rarely united on the same peduncle; staminate heads dark red on axillary peduncles; pistillate heads light green tinged with red, on long terminal peduncles, the lateral heads in the spicate clusters sessile and embracing at maturity the peduncle, usually persistent on the branches during the winter; calyx of the staminate flower divided into 3—6 minute scale-like sepals slightly united at base, about half as long as the 3—6 cuneiform sulcate scarious pointed petals; stamens as many as the divisions of the calyx, opposite them, with short nearly obsolete filaments, and elongated clavate 2-celled anthers, their cells opening longitudinally and crowned by a capitate pilose truncate connective; calyx of the pistillate flower divided into 3—6, usually 4, rounded sepals much shorter than the acute petals; stamens scale-like, elongated-obovoid, pilose at apex; ovaries as many as the divisions of the calyx, superior, oblong, sessile, surrounded at base by long ridged jointed pale hairs persistent round the fruit, gradually narrowed into long simple bright red styles papillose-stigmatic to below the middle along the ventral suture; ovules 1 or rarely 2, suspended laterally, orthotropous. Head of fruit composed of elongated obovoid akenes rounded and obtuse or acute at apex, surmounted by the persistent styles, 1-seeded, light yellow-brown; pericarp thin, coriaceous. Seed elongated-oblong, suspended; testa thin and firm, light chestnut-brown; embryo erect in thin fleshy albumen; cotyledons oblong, about as long as the elongated cylindric erect radicle turned toward the minute apical hilum. Wood hard and heavy not strong, light brown tinged with red, with numerous broad conspicuous medullary rays and bands of smaller ducts marking the layers of annual growth. A family of a single genus.
1. PLATANUS L. Plane-tree.
Characters of the family.
A genus of four or five species of eastern and western North America, Mexico, Central America, and of southwestern Asia, all resembling each other except in the form of the lobes of the leaves and the amount of pubescence on their lower surface, in the pointed or obtuse apex of the akene, and in the number of heads of pistillate flowers on their peduncle.
Of the exotic species, the Old World Platanus acerifolia Willd., of doubtful origin, and often considered a hybrid between P. orientalis L. and the Plane-tree of the eastern United States, is now a common street tree in the cities of all the countries of temperate Europe, and is largely used as a street and shade tree in the eastern states and in California.
Platanus is the classical name of the Plane-tree.
CONSPECTUS OF THE NORTH AMERICAN SPECIES.
Heads of fruit usually solitary; leaves broadly ovate, slightly 3—5-lobed, the lobes broad, mostly serrulate, or entire, truncate or rarely cuneate at base.1. [P. occidentalis] (A, C). Heads of fruit racemose. Leaves 3—5-lobed to below the middle, the lobes entire, remotely and obscurely dentate, or rarely sinuate-toothed, truncate or slightly cordate or cuneate at base.2. [P. racemosa] (G). Leaves deeply 5—7-lobed, the lobes elongated, slender, entire, or rarely remotely dentate, deeply cordate or rarely cuneate or truncate at base.3. [P. Wrightii] (H).