CACTACEJB 759 



fleshy valves bright red on their inner surface and inclosing the bright scarlet juicy mass 

 of the enlarged funiculi and innumerable seeds; seeds obovoid, rounded, -' long, lustrous, 

 dark chestnut-brown. 



A tree, 50-60 high, with a trunk sometimes 2 in diameter, thickest below the middle 

 and tapering gradually toward the ends, marked by transverse superficial lines into rings 

 4'-8' long, representing the amount of annual longitudinal growth, 8-12-ribbed at base 

 with obtuse ribs 4 '-5' broad, and at summit 18-20-ribbed with obtuse deep compressed ribs, 

 branchless or furnished above the middle with a few, usually 2 or 3, stout alternate or some- 

 times opposite upright branches shorter but otherwise resembling the principal stem com- 

 posed of a thick tough green epidermis, a fleshy covering 3' -6' thick saturated with bitter 

 juice, and a circle of bundles of woody fibres making, with annual layers of exogenous 

 growth, dense tough elastic columns placed opposite the depressions between the ribs, 

 '-3' in diameter and frequently united by branches growing at irregular intervals between 

 them, the woody frame remaining standing after the death of the plant and the decomposi- 

 tion of its fleshy covering. Areolae pale, elevated, about |' in diameter, bearing clusters of 

 stout straight spines with a large dark fulvous base, sulcate or angled, tinged with red, with 

 thick stout spines in the centre of each cluster, the 4 basal horizontal or slightly inclined 

 downward, the lowest being the longest and stoutest and sometimes 1 \' long and -$' thick, 

 the upper shorter, more slender and slightly turned upward, with a row of shorter and 

 thinner radial spines 12-16 in number surrounding the central group. Wood of the columns 

 strong, very light, rather coarse-grained, with numerous conspicuous medullary rays, and 

 light brown tinged with yellow; almost indestructible in contact with the ground, little 

 affected by the atmosphere and largely used for the ratters of houses, for fences, and by In- 

 dians for lances, bows, etc. The fruit is consumed in large quantities by Indians. 



Distribution. Low rocky hills and dry mesas of the desert; valley of Bill Williams River 

 through central and southern Arizona to the valley of the San Pedro River and to the 

 eastern border of the Colorado Desert between the Needles and Yuma, Yuma County, 

 Arizona, and southward in Sonora. 



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 

 areolae 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 areolse 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 edi- 

 ble, 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 mar- 

 ginal 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 Chili, 

 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 



