CACTACE^ 687 



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 rafters of houses, for fences, and by Indians 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 Wil- 

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

 River, and southward in Sonora. 



2. OPUNTIA, Adans. 



Trees or usually shrubs, in the arborescent species of the United States with sub- 

 cylindrical or clavate articulate tuberculate branches, covered with small sunken sto- 

 mata, 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 the apex, by loose papery sheaths. Flowers diurnal, lat- 

 eral, produced from areolae on branches of the previous year between the bristles 

 and spines, sessile, cup-shaped; sepals fiat, erect, deciduous; corolla rotate; petals 

 obovate, united at the base, spreading; stamens shorter than the petals; filaments 

 free or slightly united below; anthers oblong; style cylindrical, longer than the 

 stamens, obclavate below, divided at the 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 elliptical, concave at the apex, 

 surmounted by the marcescent tube of the flower, tuberculate, areolate, or rarely 

 glabrous, truncate at the base, with a broad umbilicus at the 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 about one hundred and thirty 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 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 Bceotia. 



CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES. 



Tubercles of the branches full and rounded below the areolae. 



Joints pale olive color, easily separable, their tubercles broad, mammillate ; spines yel- 

 low ; flowers pink ; fruit proliferous, usually spineless, often sterile. 



1. O. fulgida (H). 



