Opuntia megacantha Salm Dyck Hort Dyck 363 1834
Opuntia castillae Griffiths, Rep. Mo. Bot. Gard. 19: 261. 1908.
? Opuntia incarnadilla Griffiths, Rep. Mo. Bot. Gard. 22: 27. 1912.
Plant tall, 4 to 5 meters high or more, with a more or less definite woody trunk; joints of large plants obovate to oblong, often oblique, sometimes 40 to 60 cm. long or more, but in greenhouse specimens often much smaller, pale dull green, slightly glaucous; leaves minute, often only 3 mm. long, green or purplish; areoles rather small, on large joints often to 5 cm. apart, when young bearing brown wool; spines white, usually 1 to 5, slightly spreading, sometimes nearly porrect, usually only 2 to 3 cm. long, sometimes few and confined to the upper areoles; glochids few, yellow, caducous, sometimes appearing again on old joints; flowers yellow to orange, about 8 cm. broad; ovary spiny or spineless, obovoid; fruit 7 to 8 cm. long.
Type locality: In Mexico.
Distribution: Much cultivated in Mexico; grown also in Jamaica and southern California and escaped from cultivation in Hawaii.
This species was originally described by Salm-Dyck essentially as follows: Erect and of the size of O. decumana; joints 17.5 cm. long by 7.5 cm. broad and 2.5 cm. or more thick; areoles close together, filled with gray wool; glochids brownish, becoming blackish; spines 7 to 10, white, unequal, acicular, somewhat radiating, the longest one deflexed, 5 cm. long; flowers not known; leaves small, reddish.
Opuntia megacantha trichacantha Salm-Dyck was given as a synonym of this species by Förster (Handb. Cact. 486. 1846), but was never published.
Opuntia tribuloides Griffiths (Monatsschr. Kakteenk. 23: 137. 1913), according to the description, is of this relationship.
This is the chief Mission cactus. It is the one from which the best varieties of edible tunas are obtained and is one of the commonest cultivated opuntias in Mexico, having numerous forms, many of them bearing local names.
Illustrations: Ariz. Agr. Exp. Sta. Bull. 67: pl. 8, f. 2; Rep. Mo. Bot. Gard. 19: pl. 24, both as Opuntia castillae. Rep. Mo. Bot. Gard. 22: pl. 4, 5, these two as Opuntia incarnadilla; Amer. Journ. Bot. 4: 572. f. 6.
Plate xxxii, figure 4, represents a flowering joint of a plant in the same collection received from Fairmount Park, Philadelphia, in 1905. Figure 226 is from a photograph of a plant in the collection of the New York Botanical Garden; Fig 228.—Opuntia megacantha. X0.4.
figure 227 is from a photograph taken by A. S. Hitchcock on Lanai in 1916; figure 228 represents a joint of a plant obtained by Dr. MacDougal near Mount Wilson, California, in 1906, a nearly spineless form.
207. Opuntia deamii Rose, Contr. U. S. Nat. Herb. 13: 309. 1911.
One meter or so high, with a definite cylindric trunk, branching a short distance above the base; branches few, ascending; joints erect or spreading, very large, obovate to oblanceolate, 25 to 30 cm. long, at first bright leaf-green, in age dark green, glabrous; areoles remote, often 4 cm. apart, rather small; spines 2 to 6, usually 4, white or dull yellow, stout, somewhat flattened, spreading or porrect, 3 to 5.5 cm. long; flowers 7 cm. long, reddish; fruit oblong, 6 cm. long, naked, except for a few spines near the top, wine-red both within and without, not edible; seeds small, 3 mm. broad.
Type locality: Fiscal, Guatemala.
Distribution: Fiscal to San José de Golfo and Sanarata, Guatemala.
Figure 229 represents a joint of the type specimen.
A tall, white-spined Opuntia, closely resembling the Mexican O. macracantha, was obtained by Dr. Rose in 1918 (No. 22390) along roadsides at Ambato, Ecuador, presumably escaped from cultivation; its fruit is edible.
Continue reading here: U S Nat Herb 13 310
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