2. OPUNTIA Adans.
Trees or usually shrubs, in the arborescent species of the United States with subcylindric or clavate articulate tuberculate branches, covered with small sunken stomata, and containing tubular reticulated woody skeletons, and thick fleshy or fibrous roots. Leaves scale-like, terete, subulate, caducous, bearing in their axils oblong or circular cushion-like areolæ of chaffy or woolly scales terminal on the branches and furnished above the middle with many short slender slightly attached sharp barbed bristles and toward the base with numerous stout barbed spines surrounded in some species, except at apex, by loose papery sheaths. Flowers diurnal, lateral, produced from areolæ on branches of the previous year between the bristles and spines, sessile, cup-shaped; sepals flat, erect, deciduous; corolla rotate; petals obovate, united at base, spreading; stamens shorter than the petals; filaments free or slightly united below; anthers oblong; style cylindric, longer than the stamens, obclavate below, divided at apex into 3—8 elongated or lobulate lobes stigmatic on the inner face. Fruit sometimes proliferous, covered by a thick skin, succulent and often edible, or dry, pyriform, globose or ellipsoid, concave at apex, surmounted by the marcescent tube of the flower, tuberculate, areolate, or rarely glabrous, truncate at base, with a broad umbilicus at apex. Seeds immersed in the pulpy placentas, compressed, discoid, often margined with a bony raphe; testa pale, bony, sometimes marked by a narrow darker marginal commissure; embryo coiled around the copious or scanty albumen; cotyledons large; radicle thin, obtuse.
Opuntia with many species is distributed from southern New England southward in the neighborhood of the coast to the West Indies, and through western North America to Chile, Brazil, and Argentina, the largest number of species occurring near the boundary of the United States and Mexico. Of the species of the United States at least three attain the size and habit of small trees. Cochineal is derived from a scale-insect which feeds on the juices of some of the Mexican species, and the fruit of several species is refreshing and is consumed in considerable quantities in semitropical countries. The large-growing species with flat branches are employed in many countries to form hedges for the protection of gardens and fields; and the branches saturated with watery juice are sometimes stripped of their spines and bristles and fed to cattle.
Opuntia is the classical name of some plant which grew in the neighborhood of the city of Opus in Bœotia.
CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES.
Tubercles of the branches full and rounded below the areolæ. Joints pale olive color, easily separable, their tubercles broad, mammillate; spines yellow; flowers pink; fruit proliferous, usually spineless, often sterile.1. [O. fulgida] (H). Joints green or purple, their tubercles narrow, ovoid; spines white to reddish brown; flowers purple; fruit yellow, sparingly spinescent, rarely proliferous.2. [O. spinosior] (H). Tubercles of the branches not full and rounded below the areolæ; joints elongated, dark green or purple, their tubercles elongated; spines brown or reddish brown; flowers green, tinted with red or yellow; fruit green, spinescent, rarely proliferous.3. [O. versicolor] (H).
1. [Opuntia fulgida] Engelm. Cholla.
Leaves light green, gradually narrowed to the acuminate apex, ½′—1′ long. Flowers appearing from June to September, the earliest from tubercles at the end of the branches of the previous year, the others from the terminal tubercles of the immature fruit developed from the earliest flowers of the season, 1′ in diameter when fully expanded, with ovaries nearly 1′ long, 8—10 obtuse crenulate sepals, 5 erect stigmas, and 8 light pink petals, those of the outer ranks cuneate, retuse, crenulate on the margins, shorter than the lanceolate acute petals of the inner ranks, the whole strongly reflexed at maturity. Fruit proliferous, oval, rounded, 1′—1¼′ long and nearly as broad, more or less tuberculate, conspicuously marked by large pale tomentose areolæ bearing numerous small bristles, usually spineless or occasionally armed with small weak spines, hanging in pendulous clusters usually of 6 or 7 and occasionally of 40—50 fruits in a cluster, one growing from the other in continuous succession, the first the largest and containing perfect seeds, the others frequently sterile, dull green when fully ripe, with dry flesh, falling usually during the first winter or occasionally persistent on the branches during the second season, and then developing flowers from the tubercles; seeds compressed, thin, very angular, 1/12′—⅙′ in diameter.
A tree, with a more or less flexuous trunk occasionally 12° in height and sometimes a foot in diameter, a symmetric head of stout wide-spreading branches and thick pendulous joints sometimes almost hidden by the long conspicuous spines and beginning to develop their woody skeletons during their second or occasionally during their third season, the terminal or ultimate joints ovoid or ovoid-cylindric, tumid, crowded at the end of the limbs, pale olive color, 3′—8′ long, often 2′ in diameter, with broad ovoid-oblong tubercles, ½′—¾′ in length. Areolæ of pale straw-colored tomentum and short slender pale bristles, each areola bearing at first 5—15 stout stellate-spreading light yellow spines of nearly equal length, ¾′-1′ long and inclosed in loose lustrous sheaths, additional spines developing in succeeding years at the upper margin of the areolæ, the tubercles of old branches being sometimes furnished with from 40-60 spines persistent on the branches for 4-6 years. Bark of the trunk and of the large limbs about ¼′ thick, separating freely on the surface into large thin loosely attached scales varying in color from brown to nearly black on the largest stems, and unarmed, the spines mostly falling with the outer layers from branches 3′—4′ thick. Wood of old trunks light, hard, pale yellow, with broad conspicuous medullary rays, well marked layers of annual growth, and a thick pith.
Distribution. Plains of Arizona south of the Colorado plateau, and in the adjacent region of Sonora; not rare; apparently most abundant and of its largest size in the United States on the mesas near Tucson, Pima County, at altitudes between 2000° and 3000°.
2. [Opuntia spinosior] Toumey. Tassajo.
Leaves terete, tapering gradually to the setulose apex, about ¼′ long, remaining on the branches from four to six weeks. Flowers opening in April and May and remaining open for two or three days, 2′—2½′ in diameter, with ovaries about 1′ long, obovate sepals, broad-obovate dark purple petals, sensitive red stamens, and a 6—9-parted stigma. Fruits clustered at the end of the branches of the previous year, persistent during the winter and occasionally during the following summer and then sometimes proliferous, oval or rarely globose or hemispheric, frequently 2′ long and 1½′ thick, with yellow acrid flesh and 20—30 tubercles very prominent during the summer, nearly disappearing as the fruit ripens and enlarges, leaving it marked only by the small oval areolæ covered with short bristles, and bearing numerous slender spines deciduous in December as the fruit begins to turn yellow; seeds nearly orbicular, slightly or not at all beaked, ⅙′—⅕′ in diameter, and marked by linear conspicuous commissures.
A tree, with an erect trunk occasionally 10° high and 5′-10′ in diameter, numerous stout spreading limbs forming an open irregular head, and branches with joints 4′—12′ long and ¾′—1′ thick, covered with a thick epidermis varying from green to purple, and usually developing woody skeletons during their second season, their tubercles prominent, compressed, ovoid, ⅓′—½′ long. Areolæ oval, clothed with pale tomentum and short light brown bristles, their spines 5—15 on the tubercles of young joints and 30—50 on those of older branches, and slender, white to light reddish brown, closely invested in white glistening sheaths, stellate-spreading, ½′—¾′ long, those in the interior sometimes considerably longer than the radial spines. Bark of the trunk and of the larger limbs about ¼′ thick, spineless, nearly black, broken into elongated ridges, and finally much roughened by numerous closely appressed scales. Wood light, soft, pale reddish brown, and conspicuously reticulate, with conspicuous medullary rays and well defined layers of annual growth; sometimes used in the manufacture of light furniture, canes, picture-frames, and other small articles.
Distribution. Widely scattered over the mesas of southern Arizona south of the Colorado plateau and of the adjacent regions of Sonora.
3. [Opuntia versicolor] Coult.
Leaves terete, abruptly narrowed to the spinescent apex, ⅓′—½′ long, persistent on the branches from four to six weeks. Flowers opening in May, about 1½′ in diameter, with ovaries ⅝′ long, broad-ovate acute sepals, and narrow obovate petals rounded above and green tinged with red or with yellow. Fruit usually clavate, 2′—2½′ long, nearly 1½′ in diameter, with areolæ generally only above the middle and usually furnished with 1—3 slender reflexed persistent spines about ½′ long, or occasionally spineless, rarely nearly spherical and only about ¾′ in diameter, ripening from December to February, and at maturity the same color as the joint on which it grows, usually withering, drying, and splitting open on the tree, or remaining fleshy and persistent on the branches until the end of the following summer, and sometimes through a second winter, or often becoming imbedded in the end of a more or less elongated joint; seeds irregularly angled, with narrow commissures.
A tree, with an erect trunk occasionally 6°—8° high and 8′ in diameter, numerous stout irregularly spreading or often upright branches, and cylindric terminal joints generally 6′—12′ but sometimes 2° in length, ¾′—1′ in diameter, and covered with a thick dark green or purple epidermis, marked by linear flattened tubercles, their woody skeletons usually formed during their second season. Areolæ large, oval, clothed with gray wool, generally bearing a cluster of small bristles, and slender stellate-spreading brown or reddish brown spines, with close early deciduous straw-colored sheaths, 4—14 and on old tubercles 20—25 in number, the inner 1—4 in number, usually deflexed and unequal in length, the longest about ⅓′ long and longer than the radial spines. Bark of the trunk and of the large branches smooth, light brown or purple, usually unarmed, ½′—¾′ thick, finally separating into small closely appressed black scales. Wood reticulate, hard, compact, light reddish brown and rather lustrous, with thin conspicuous medullary rays, well-defined layers of annual growth, and thick pale or nearly white sapwood.
Distribution. Foothills and low mountain slopes of southern Arizona and northern Sonora; very abundant.