Part 78

Trees or shrubs, with slender branches armed with spinescent stipules or infrastipular spines. Leaves alternate on young branchlets and fascicled in earlier axils, bipinnate, with usually small leaflets, persistent. Flowers perfect or polygamous, small, in the axils of minute linear bractlets more or less dilated and often peltate at apex, in globose heads or cylindric spikes on axillary solitary or fascicled peduncles; calyx campanulate, 5 or 6-toothed; petals as many as the divisions of the calyx, more or less united; stamens numerous, usually more than 50, exserted, free or slightly and irregularly united at base, inserted under or just above the base of the ovary; filaments filiform; anthers small, attached on the back, versatile; ovary contracted into a long slender style terminating in a minute stigma. Legume nearly cylindric or flat, indehiscent, continuous or divided within. Seeds transverse, compressed; seed-coat thick, crustaceous, marked on each face of the seed by an oval depression or ring; radicle straight, included, or slightly exserted.

Acacia with more than four hundred species is widely distributed through Australia, where it is most largely represented, tropical and southern Africa, northern Africa, southwestern China, the warmer regions of southern Asia, the islands of the south Pacific, tropical and temperate South America, the West Indies, Central America and Mexico to the southwestern boundaries of the United States where ten or twelve species occur; of these five are arborescent. Acacia is astringent, and many species yield valuable tan bark. Gum arabic is produced by different Old World species; many of the species yield hard heavy durable wood, and some of the Australian Acacias are large and valuable timber-trees. Many species are cultivated for their graceful foliage and handsome fragrant flowers.

The generic name, from ἀκακία, relates to the spines with which the branches are usually armed.

CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES.

Flowers in globose heads; corolla 5-lobed; ovary sessile; stipules persistent, becoming spines. Legume cylindric, glabrous, its sutures conspicuously thickened and grooved; seeds in 2 ranks. 1. A. Farnesiana (E). Legume flattened, pubescent, its sutures not thickened, slightly grooved; seeds in 1 rank. 2. A. tortuosa (E). Flowers in short, often interrupted, spikes; legume flattened, pubescent, its sutures thickened; seeds in one rank. 3. A. Emoriana (E). Flowers in elongated slender spikes; corolla of 5 petals only slightly united at base; ovary stalked; stipules caducous; branchlets armed with infrastipular spines. Legume 1′—1¼′ wide, straight or slightly contracted between the seeds, not becoming twisted and contorted at maturity; seeds narrow-obovoid or ovoid; leaflets green, glabrous, with prominent veinlets. 4. A. Wrightii (E). Legume ½′—¾′ wide, often conspicuously contracted between the seeds, becoming twisted and contorted at maturity; seeds nearly orbicular; leaflets blue-green, pubescent, with obscure veinlets. 5. A. Greggii (E, G, H).

1. Acacia Farnesiana Willd. Huisache. Cassie.

Leaves 2′—4′ long, with 2—8, usually 4 or 5, pairs of pinnæ, generally somewhat puberulous on the short petiole and rachis; in Texas mostly falling at the beginning of winter; pinnæ sessile or short-stalked, remote or close together, with 10—25 pairs of linear acute leaflets tipped with a minute point, unequal at base, sessile or short-petiolulate, glabrous or puberulous, bright green, ⅛′—¼′ long. Flowers bright yellow, very fragrant, 1/16′ long, opening during the summer and autumn from the axils of minute clavate pilose bractlets, in heads ⅔′ in diameter, on axillary thin puberulous peduncles, solitary or most often 2 or 3 together and 1′—1½′ in length, with two minute dentate connate bracts forming an involucral cup immediately under the flower-head; calyx about half as long as the petals and like them somewhat pilose on the outer surface; stamens two or three times as long as the corolla; ovary short-stipitate, covered with long pale hairs. Fruit oblong, cylindric or spindle-shaped, thick, turgid, straight or curved, slightly contracted between the seeds, short-stalked, narrowed at apex into a short thick point, 2′—3′ long, ½′—⅔′ broad, dark red-purple, lustrous, and marked by broad light-colored bands along the thickened grooved sutures, the outer coat of the walls thin and papery, inclosing a thick pithy pulp-like substance surrounding the seeds, each in a separate thin-walled compartment; seeds ovoid, thick, flattened on the inner surface by mutual pressure, ¼′ long, suspended transversely in 2 ranks on a short straight funicle, light brown, lustrous, and faintly marked by large oval rings.

A tree, 20°—30° high, with a straight trunk 12′—18′ in diameter, separating 6°—8° from the ground into numerous long pendulous branches forming a wide round spreading head, and slender terete or slightly striate angled branchlets, glabrous or at first puberulous, and armed with straight rigid terete spines developed from the persistent stipules and sometimes 1½′ long. Bark of the trunk thin, reddish brown, irregularly broken by long reticulated ridges, exfoliating in large thin scales. Wood heavy, hard, close-grained, rich reddish brown, with thin pale sapwood; in India used for the knees of small vessels and in agricultural implements.

Distribution. Now widely spread by cultivation through the tropical and subtropical regions of the two worlds and probably a native of America from western Texas to northern Chile; growing in Texas apparently naturally in the arid and almost uninhabited region between the Nueces and Rio Grande; naturalized and now covering great areas in the valley of the Guadalupe River near Victoria, Victoria County, Texas.

Largely cultivated in southern Europe for its fragrant flowers used in the manufacture of perfumery, as an ornament of gardens in all warm countries, and in India as a hedge plant.

2. Acacia tortuosa Willd.

Leaves generally less than 1′ long, short-petiolate, with a slender puberulous rachis and usually 3 or 4 pairs of pinnæ; early deciduous; pinnæ sessile or short-stalked, remote, with 10—15 pairs of linear somewhat falcate leaflets, acute, tipped with a minute point, subsessile, light green, glabrous, 1/20′—1/16′ long. Flowers minute, bright yellow, very fragrant, in the axils of clavate pilose bracts, in heads ¼′—⅜′ in diameter, appearing in March with or just before the unfolding leaves, on clustered or solitary slender puberulous peduncles ½′—¾′ long, and furnished at apex with 2 minute connate bracts; calyx only about one third as long as the corolla, with short puberulous lobes; corolla puberulous at apex, less than half as long as the filaments; ovary covered with short close pubescence. Fruit elongated, linear, slightly compressed, somewhat constricted between the seeds, dark red-brown and cinereo-puberulous, 3′—5′ long and about ¼′ wide; seeds in 1 series, obovoid, compressed, dark red-brown, lustrous, about ¼′ long, faintly marked by large oval rings.

A tree, occasionally 15°—20° high, with a straight trunk 5′—6′ in diameter, stout wide-spreading branches forming an open irregular head, and slender somewhat zigzag slightly angled reddish brown branchlets roughened by numerous minute round lenticels, villose with short pale hairs, and armed with thin terete puberulous spines occasionally ¾′ long; in Texas usually shrubby, with numerous stems forming a symmetric round-topped bush only a few feet high. Bark dark brown or nearly black, and deeply furrowed.

Distribution. Valley of the Rio Cibolo to Eagle Pass on the Rio Grande, Maverick County, Texas; and in northern and southern Mexico, the West Indies, Venezuela, and on the Galapagos Islands; in Texas probably arborescent only on the plains of the Rio Grande near Spofford, Kinney County.

3. Acacia Emoriana Benth.

Leaves 3½′—4′ long, with a slender petiole and rachis, villose-pubescent early in the season, becoming nearly glabrous; and 4 or 5 pairs of pinnæ; falling late in the autumn; pinnæ on slender stalks ¼′ in length, with 5—7 pairs of oblong leaflets rounded and apiculate at apex, obliquely rounded at base, short-petiolulate, pointing forward, when they unfold densely villose above and on the margins, and hoary-tomentose below, becoming glabrous, gray-green rather darker above than below, ⅓′ long. Flowers subsessile, puberulous, in interrupted spikes, ¾′—1′ in length, densely hoary-tomentose when they first appear late in March, on villose peduncles ½′—1′ in length, and furnished near the apex with lanceolate caducous bracts; calyx about half the length of the ovate acute petals ciliate on the margins, about 1/12′ long and much shorter than the stamens; ovary stipitate, glabrous. Fruit fully grown in July, stipitate much compressed, rounded and sometimes slightly emarginate at apex, gradually narrowed and obliquely cuneate at base, with much thickened revolute undulate margins, densely pubescent early in the season, becoming puberulous, 5′ or 6′ long, 1¼′—1½′ wide and many-seeded, or nearly orbicular and 1 or 2-seeded; seeds in one series, oval, the two sides unsymmetric, obliquely pointed at base, rounded at apex, compressed, dark chestnut-brown and lustrous, ½′ long and ¼′ wide.

A tree, sometimes 25° high, usually smaller, with slender red-brown branchlets pubescent or puberulous when they first appear, becoming glabrous in their second year, and armed with small curved stipular spines; often a shrub.

Distribution. Texas; creek banks and cañons, near Montell and Uvalde, Uvalde County, and rocky banks of Devil’s River, Valverde County (_E. J. Palmer_).

4. Acacia Wrightii Benth. Cat’s Claw.

Leaves 1′—2′ long, slightly pubescent, especially on the petiole and rachis, with 1—3 pairs of pinnæ, slender petioles 1⅓′ in length, and eglandular or glandular with small convex glands, and linear acute caducous stipules 1/16′ long; pinnæ short-stalked, with 2—5 pairs of obovate-oblong leaflets, obliquely rounded and often apiculate at apex, sessile or short-petiolulate, 2 or sometimes 3-nerved, glabrous, or rarely pubescent, reticulate-veined, rigid, bright green and rather paler on the lower surface than on the upper surface, ¼′—⅚′ long. Flowers light yellow, fragrant, appearing from the end of March to the end of May, on slender pubescent pedicels from the axils of minute caducous bracts, in narrow spikes 1½′ long, often interrupted below the middle, on slender fascicled pubescent or sometimes glabrous peduncles; calyx obscurely 5-lobed, pubescent on the outer surface, half as long as the spatulate petals slightly united at base, and ciliate on the margins; stamens ¼′ long; ovary long-stalked, covered with long pale hairs. Fruit fully grown early in the summer, deciduous in the autumn, slightly falcate, compressed, stipitate, oblique at base, rounded and short-pointed at apex, 2′—4′ long, 1′—1¼′ wide, with thick straight or irregularly contracted margins and thin papery walls conspicuously marked by narrow horizontal reticulate veins; seeds narrow-obovoid, compressed, ¼′ long, suspended transversely on a long slender funicle, light brown, marked by large oval depressions.

A tree, occasionally 25°—30° high, with a short trunk 10′—12′ in diameter, spreading branches forming a low wide or irregular head, and branchlets when they first appear somewhat striately angled, glabrous, pale yellow-brown or dark red-brown, turning pale gray in their second year, and armed with occasional stout recurved infrastipular chestnut-brown spines ¼′ long, compressed toward the broad base and sharp-pointed, or rarely unarmed. Bark of the trunk about ⅛′ thick, divided by shallow furrows into broad ridges separating on the surface into thin narrow scales. Wood very heavy, hard, close-grained, bright clear brown streaked with red and yellow, with thin clear yellow sapwood of 6 or 7 layers of annual growth; valued and largely used as fuel.

Distribution. Valley of the Guadalupe River in the neighborhood of New Braunfels, Comal County, Texas, to the Sierra Madre of Nuevo Leon; most abundant and of its largest size south of the Rio Grande on dry gravelly mesas and foothills.

5. Acacia Greggii A. Gray. Cat’s Claw. Una de Gato.

Leaves 1′—3′ long, pubescent or puberulous, with 1—3 pairs of pinnæ, a short slender petiole furnished near the middle with a minute oblong chestnut-brown gland, and linear caducous stipules 1/16′ long; pinnæ short-stalked, with 4—5 pairs of obovate oblique leaflets rounded or truncate at apex and unequally contracted at base into a short petiolule, thick and rigid, 2—3-nerved, inconspicuously reticulate-veined, hoary-pubescent, 1/16′—¼′ long. Flowers fragrant, bright creamy yellow, in dense oblong pubescent spikes, on a peduncle ½′—⅔′ long, and fascicled usually 2 or 3 together toward the end of the branches; calyx obscurely 5-lobed, puberulous on the outer surface, half as long as the petals slightly united at base and pale-tomentose on the margins; stamens ¼′ long; ovary long-stalked, covered with long pale hairs. Fruit fully grown at midsummer and hanging unopened on the branches until winter or the following spring, compressed, straight or slightly falcate, obliquely narrowed at base into a short stalk, acute or rounded at apex, more or less contracted between the seeds, 2′—4′ long, ½′—¾′ wide, curling and often contorted when fully ripe, the valves thin and membranaceous, thick-margined, light brown, conspicuously transversely reticulate-veined; seeds nearly orbicular, compressed, dark brown and lustrous, ¼′ in diameter, marked by small oval depressions.

A tree, rarely 30° high, with a trunk 10′—12′ in diameter, numerous spreading branches, and striately angled puberulous or in Texas glabrous pale brown branchlets faintly tinged with red and armed with stout recurved infrastipular spines flat at base, and ¼′ long and broad. Bark of the trunk about ⅛′ thick, furrowed, the surface separating into thin narrow scales. Wood heavy, very hard, strong, close-grained, durable, rich brown or red, with thin light yellow sapwood of 5 or 6 layers of annual growth.

Distribution. Dry gravelly mesas, the sides of low cañons and the banks of mountain streams; valley of the Rio Grande, western Texas, through southern New Mexico and Arizona to southern California, ranging northward in Arizona to the rim of the Grand Cañon of the Colorado River, and to Clark County, Nevada; in northern Mexico, and in Lower California to the eastern base of the San Pedro Mártir Mountains.

4. LEUCÆNA Benth.

Trees or shrubs, with slender unarmed branches. Leaves persistent, abruptly bipinnate, with numerous pinnæ and small leaflets in many pairs, petiolate, the petioles often furnished with a conspicuous gland below the lower pair of pinnæ; stipules minute and caducous, or becoming spinescent and persistent. Flowers minute, white, mostly perfect, sessile or short-pedicellate, in the axils of small peltate bracts villose at apex, in globose many-flowered pedunculate heads, the peduncles in axillary fascicles or in leafless terminal racemes; calyx tubular-campanulate, minutely 5-toothed; petals 5, free, acute or rounded at apex, narrowed at base; stamens 10, free, inserted under the ovary, exserted; filaments filiform; anthers oblong, versatile; ovary stipitate, contracted into a long slender style, with a minute terminal slightly dilated stigma. Legume many-seeded, stipitate, linear, compressed, dehiscent, the valves thickened on the margins, rigid, thin, continuous within, their outer coat thin and papery, dark-colored, the inner rather thicker, woody, pale brown. Seeds obovoid, compressed, transverse, the hilum near the base, suspended on a long slender funicle; seed-coat thin, crustaceous, brown and lustrous; embryo inclosed on its two sides by a thin layer of horny albumen; radicle slightly exserted.

Leucæna with nine or ten species is confined to the warmer parts of America from western Texas to Venezuela and Peru, and to the islands of the Pacific Ocean from New Caledonia to Tahiti, where one species has been recognized. Of the indigenous species found in the territory of the United States, three are arborescent. _Leucæna glauca_ L., a small tree or shrub, cultivated in all warm countries, and a native probably of tropical America, is now naturalized on Key West, Florida.

The generic name, from λευχαίνω, refers to the color of the flowers.

CONSPECTUS OF THE NORTH AMERICAN SPECIES.

Peduncles bibracteolate at apex; stipules becoming spinescent. Leaves 10—14-pinnate; pinnæ with 15—30 pairs of leaflets; blade of the bract of the flower produced into a short point. 1. L. Greggii (E). Leaves 2—4-pinnate; pinnæ with 4—8 pairs of leaflets; blade of the bract of the flower produced into a long slender villose tip. 2. L. retusa (E). Peduncles without bracts; stipules minute, caducous; leaves 30—36-pinnate; pinnæ with 30—60 pairs of leaflets. 3. L. pulverulenta (E).

1. Leucæna Greggii S. Wats.

Leaves 6′—7′ long and broad, with a slender rachis furnished on the upper side with a single elongated bottle-shaped gland between the stalks of each pair of pinnæ; pinnæ 10—14, remote, short-stalked, with 15—30 pairs of leaflets; stipules gradually narrowed into a long slender point, becoming rigid and spinescent, ⅓′ to nearly ½′ long and persistent for two or three years; leaflets lanceolate, acute or acuminate, often somewhat falcate, nearly sessile or short-petiolulate, full and rounded toward the base on the lower margin, nearly straight on the upper margin, gray-green, ultimately nearly glabrous, ¼′—⅓′ long, about ⅛′ wide, with a narrow midvein and obscure lateral nerves. Flowers on slender pedicels, in heads ¾′—1′ in diameter, on stout peduncles 2′—3′ long furnished at apex with 2 irregularly 3-lobed bracts, and solitary or in pairs; calyx coated with hairs only near the apex, much shorter than the spatulate glabrous more or less boat-shaped petals; ovary villose with a few short scattered hairs. Fruit 6′-8′ long, ⅓′—½′ wide, narrowed below into a short stout stipe, acuminate and crowned at apex with the thickened style, ⅓′—¾′ long, cinereo-pubescent until nearly fully grown, becoming nearly glabrous at maturity, much compressed, with narrow wing-like margins; seeds conspicuously notched by the hilum, ½′ long and ⅓′ wide.

A tree, 15°-20° high, with a stem 4′—5′ in diameter, and stout zigzag red-brown branchlets marked by numerous pale lenticels, coated at first with short spreading lustrous yellow deciduous hairs found also on the young petioles and lower surface of the unfolding leaflets, the peduncles of the flower-heads and their bracts. Bark about ⅜′ thick, dark brown, divided into low ridges and broken on the surface into small closely appressed persistent scales. Wood heavy, hard, close-grained, rich brown streaked with red, with thin clear sapwood.

Distribution. Mountain ravines and the steep banks of streams; western Texas from the valley of the upper San Saba River to that of Devil’s River; and southward into Mexico.

2. Leucæna retusa Benth.

Leaves 3′ or 4′ long and 4′ or 5′ wide, with a slender petiole and rachis and 2-4 pairs of pinnæ 6′-10′ long, remote, long-stalked, with 4-8 pairs of short-stalked leaflets furnished between their stems with a single globose white gland found also occasionally on the upper side of the rachis between the stems of the pinnæ; stipules ovate, gradually narrowed into a long slender tip, ½′ in length, often persistent through the season; leaflets obliquely obovate or elliptic, rounded and apiculate at apex, obliquely rounded or cuneate at the unsymmetric base, entire, short-petiolulate, villose-pubescent like the rachis and petiole when they first appear, soon, glabrous, and at maturity thin, blue-green, ¾′—1′ long and ⅓′—½′ wide, with a slender midrib, and prominent veins extending obliquely toward the apex of the leaflet, those of the lowest pair more prominent and starting from near its base. Flowers short-stalked in the axil of a peltate bract, its blade produced into a long slender villose tip, appearing continuously from April until October in dense globose heads ¾′ in diameter, on villose bibracteolate axillary, single or fascicled peduncles 1½′—3′ in length; calyx thin, tubular, 5-toothed at apex; petals narrow-oblong, hardly longer than the calyx; stamens 10, shorter than the bract of the flower; anthers glabrous. Fruit solitary or clustered, on a puberulous peduncle 3′-5′ in length, 6′-10′ long, ⅓′—½′ wide, gradually narrowed below into a stout stipe, the acuminate apex terminating in the thickened persistent style, glabrous and dark reddish brown; seeds ⅓′ long and ¼′ wide.

A tree, occasionally 25° high, with a trunk 6′-8′ in diameter, and slender branchlets pubescent when they first appear, becoming puberulous and orange-brown or reddish brown at the end of their first season; more often a shrub.

Distribution. Texas; steep rocky hillsides, and on the summits of limestone bluffs; (Uvalde, Valverde, Kemble, Real and Jeff Davis Counties).

3. Leucæna pulverulenta Benth. Mimosa.

Leaves 4′-7′ long and 3′-4′ wide, with a slender petiole usually marked by a large dark oblong gland between the somewhat enlarged base and the lowest pair of the 30-36 nearly sessile crowded pinnæ, each with 30-60 pairs of leaflets, and minute caducous stipules, when they unfold covered like the peduncles and flower-buds with dense hoary tomentum, and at maturity puberulous on the petiole and rachis; leaflets linear, acute, rather oblique at base by the greater development of the upper side, sessile or very short-petiolulate, pale bright green, ⅙′—¼′ long. Flowers sessile, fragrant, in heads ½′ in diameter, appearing in succession as the branches grow from early spring to midsummer, on slender peduncles 1′—1½′ long and fascicled in the axils of upper leaves; calyx one fourth as long as the acute petals and like them pilose on the outer surface; stamens twice as long as the petals; ovary coated with long pale hairs. Fruit conspicuously thick-margined, 4′-14′ long, long-stalked, tipped with a short straight or recurved point, usually in pairs on a peduncle thickened at apex; seeds 5/16′ long.

A tree, 50°-60° high, with a straight trunk 18′-20′ in diameter, separating 20°-30° from the ground into slender spreading branches forming a loose round head, and branchlets at first more or less striately grooved and thickly coated with pulverulent caducous tomentum, becoming at the end of a few weeks terete, pale cinnamon-brown and puberulous. Bark about ¼′ thick, bright cinnamon-brown, and roughened by thick persistent scales. Wood heavy, hard, very close-grained, rich dark brown, with thin clear yellow sapwood of 2 or 3 layers of annual growth; considered valuable, and sometimes manufactured into lumber.

Distribution. Rich moist soil of river banks and the borders of lagoons and small streams; valley of the lower Rio Grande; in Texas only for a few miles near its mouth; more abundant from Matamoras to Monterey in Nuevo Leon; and southward to the neighborhood of the City of Mexico.