1. MORUS L. Mulberry.
Trees or shrubs, with slender terete unarmed branches prolonged by one of the upper axillary buds, scaly bark, fibrous roots, and winter-buds covered by ovate scales closely imbricated in 2 ranks, increasing in size from without inward, the inner accrescent, marking in falling the base of the branch with ring-like scars. Leaves conduplicate in the bud, alternate, serrate, entire or 3-lobed, 3—5-nerved at base, membranaceous or subcoriaceous, deciduous; stipules inclosing their leaf in the bud, lateral, lanceolate, acute, caducous. Flowers monœcious or diœcious, the staminate and pistillate on different branches of the same plant or on different plants, minute, vernal, in pedunculate clusters from the axils of caducous bud-scales or of the lower leaves of the year; staminate in elongated cylindric spikes; calyx deeply divided into 4 equal rounded lobes; stamens 4, inserted opposite the lobes of the calyx under the minute rudimentary ovary, filaments filiform, incurved in the bud, straightening elastically and becoming exserted, anthers attached on the back below the middle, introrse, 2-celled, the cells reniform, attached laterally to the orbicular connective, opening longitudinally; pistillate sessile, in short-oblong densely flowered spikes; calyx 4-parted, the lobes ovate or obovate, thickened, often unequal, the 2 outer broader than the others, persistent; ovary ovoid, flat, sessile, included in the calyx, crowned by a central style divided nearly to the base into 2 equal spreading filiform villose white stigmatic lobes; ovule suspended from the apex of the cell, campylotropous; micropyle superior. Drupes ovoid or obovoid, crowned with the remnants of the styles, inclosed in the succulent thickened and colored perianth of the flower and more or less united into a more or less juicy compound fruit; flesh subsucculent, thin; walls of the nutlet thin or thick, crustaceous. Seed oblong, pendulous; testa, thin, membranaceous; hilum minute, apical; embryo incurved in thick fleshy albumen; cotyledons oblong, equal; radicle ascending, incumbent.
Morus with eight or nine species is confined to eastern temperate North America, the elevated regions of Mexico, Central America and western South America, southern and western Asia, Indo-China, China, Japan, the Bonin Islands and the mountains of the Indian Archipelago. Two species occur in North America. The most valuable species, Morus alba L., a native of China and Formosa, and largely cultivated in many countries for its leaves, which are the best food of the silkworm, has been planted in large quantities in the eastern United States; and Morus nigra L., probably a native of Persia, has been introduced into the southern and Pacific states for its large dark-colored juicy fruit. Morus produces straight-grained durable light brown or orange-colored valuable wood, and sweet acidulous and refreshing fruits.
Morus is the classical name of the Mulberry-tree.
CONSPECTUS OF THE NORTH AMERICAN SPECIES.
Leaves coated below with pale pubescence; lobes of the stigma long; syncarp oblong, dark purple.1. [M. rubra] (A, C). Leaves glabrous or pubescent below; lobes of the stigma short; syncarp subglobose or short-ovoid, nearly black.2. [M. microphylla] (C, E, H).
1. [Morus rubra] L. Red Mulberry.
Leaves ovate, oblong-ovate or semiorbicular, abruptly contracted into a long broad point or acute at apex, more or less deeply cordate or occasionally truncate at base, coarsely and occasionally doubly serrate with incurved callous-tipped teeth, often, especially on vigorous young shoots, 3-lobed by broad deep oblique lateral rounded sinuses, when they unfold yellow-green, slightly pilose on the upper surface and hoary-tomentose on the lower surface, at maturity thin, dark bluish green, glabrous, smooth or scabrate above, pale and more or less pubescent below with short white hairs thickest on the orange-colored midrib, and on the primary veins arcuate and united near the margins and connected by reticulate veinlets, or sometimes hoary-tomentose below (var. tomentosa Bureau), 3′—5′ long, 2½′—4′ wide; turning bright yellow in the autumn; petioles stout, hoary-tomentose at first, becoming glabrous, ¾′—1¼′ in length; stipules lanceolate, acute, abruptly enlarged and thickened at base, sometimes tinged with red above the middle, coated with long white hairs, and often 1′ in length. Flowers appearing with the unfolding of the leaves; staminate in narrow spikes 2′—2½′ long, on stout light green peduncles covered with pale hairs; calyx divided nearly to the base into oblong concave lobes rounded at apex and hirsute on the outer surface; stamens with slightly flattened filaments narrowed from the base to the apex, and bright green anthers, their connectives orbicular, conspicuous, bright green; pistillate in oblong densely flowered spikes, 1′ long, on short hairy peduncles, a few male flowers being sometimes mixed with them; calyx divided nearly to the base into 4 thick concave lobes rounded at apex, rounded or slightly keeled on the back, the 2 outer lobes twice as wide as the others, as long as and closely investing the glabrous light green ovary. Fruit: syncarp at first bright red when fully grown, 1′—1¼′ long, becoming dark purple or nearly black and sweet and juicy when fully ripe; drupes about 1/32′ long, with a thin fleshy outer coat and a light brown nutlet; seed ovoid, acute, with a thin membranaceous light brown coat.
A tree, 60°—70° high, with a short trunk rarely exceeding 3°—4° in diameter, stout spreading smooth branches forming a dense broad round-topped shapely head, and slender slightly zigzag branchlets dark green often tinged with red, glabrous, more or less coated with pale pubescence, and covered with oblong straw-colored spots when they first appear, becoming in their first winter light red-brown to orange color and marked by pale lenticels and by large elevated horizontal nearly orbicular concave leaf-scars displaying a row of prominent fibro-vascular bundle-scars, and in their second and third years dark brown slightly tinged with red. Winter-buds ovoid, rounded or pointed at apex, ¼′ long, with 6 or 7 chestnut-brown scales, those of the outer rows broadly ovate, rounded, and slightly thickened on the back, puberulous, ciliate on the margins, and much shorter than those of the next rows, the inner scales scarious, coated with pale hairs, oblong-lanceolate, rounded or acute at apex, and ½′—⅔′ long at maturity. Bark ½′—¾′ thick, dark brown tinged with red and divided into irregular elongated plates separating on the surface into thick appressed scales. Wood light, soft, not strong, rather tough, coarse-grained, very durable, light orange color, with thick lighter colored sapwood; largely used for fencing, in cooperage, and in boat-building.
Distribution. Intervales in rich soil and on low hills; western Massachusetts, Connecticut, and Long Island to southern Ontario, central Michigan, southeastern Minnesota, eastern Iowa, southeastern South Dakota, eastern Nebraska, central Kansas and Oklahoma, and southward to the shores of Bay Biscayne and Cape Romano, Florida, and to the cañon of the Devil’s River, Valverde County, Texas; most abundant and of its largest size in the basin of the lower Ohio River and on the foothills of the southern Appalachian Mountains; ascending to altitudes of 2000°.
Occasionally planted, especially in the southern states, for its fruit valued for fattening hogs and as food for poultry. A few natural varieties, distinguished for the large size and good quality of their fruit, or for their productiveness, are occasionally propagated by pomologists.
2. [Morus microphylla] Buckl. Mulberry. Mexican Mulberry.
Morus celtidifolia Sarg., not H. B. K.
Leaves ovate, acute or acuminate, rounded or rarely truncate, or often on vigorous shoots cordate at the broad base, and 3-lobed with shallow lateral sinuses and broad coarsely serrate lobes, when they unfold coated below with pale tomentum, and puberulous above, at maturity thin and firm in texture, dark green and often roughened on the upper surface by minute pale tubercles, and paler, smooth or scabrate, and glabrous or coated with soft pubescence on the lower surface, and often hirsute with short stiff pale hairs on the broad orange-colored midrib, and on the primary veins connected by conspicuous reticulate veinlets, rarely more than 1½′ long and ¾′ wide; turning yellow in the autumn; petioles slender, hoary-tomentose, becoming pubescent, ⅓′ in length; stipules linear-lanceolate, acute, sometimes falcate, white and scarious, coated with soft pale tomentum, about ½′ long. Flowers usually diœcious, staminate short-pedicellate, in short many-flowered spikes, ½′—¾′ long; calyx dark green, covered on the outer surface with soft pale hairs, deeply divided into equal rounded lobes reddish toward the apex; stamens with bright yellow anthers, their connectives conspicuous, dark green; pistillate sessile in few-flowered spikes, rarely ⅓′ in length; calyx divided to the base into thick rounded lobes, the 2 outer lobes much broader than the others, dark green, covered with pale scattered hairs; ovary green and glabrous, with short stigmatic lobes. Fruit: syncarp ½′ long, red becoming dark purple or nearly black, sweet and palatable; drupe ⅙′ long, ovoid, rounded at the ends, with a thin fleshy outer covering and a thick-walled light brown nutlet; seed ovoid, pointed, pale yellow.
A tree, sometimes 15°—20° high, with a trunk occasionally 12′—14′ in diameter, and slender branchlets covered when they first appear with soft white hairs, soon becoming glabrous or nearly so, and in their first winter light orange-red and marked by small lenticels and small horizontal nearly orbicular elevated concave leaf-scars displaying a ring of fibro-vascular bundle-scars; often a shrub. Winter-buds ovoid, acute, sharp-pointed, and covered by thin lustrous chestnut-brown ovate rounded scales scarious on the margins, those of the inner rows ovate-oblong, rounded at apex, pale-pubescent on the outer surface, and nearly 1′ long when fully grown. Bark smooth, sometimes nearly ½′ thick but usually thinner, light gray slightly tinged with red, deeply furrowed and broken on the surface into slightly appressed scales. Wood heavy, hard, close-grained, dark orange color or sometimes dark brown, with thick light-colored sapwood.
Distribution. Dry limestone hills, or westward only in elevated mountain cañons in the neighborhood of streams; valley of the Colorado River, Texas, southward into Mexico and through the mountain regions of western Texas and southern New Mexico to the Santa Rita Mountains and the cañons of the Colorado Plateau, Arizona.