Opuntia Imbricata

Joints very readily detached, freely falling 30. O. fulgida

Joints not very readily detached, persistent.

Spines brown or reddish, at least at base.

Branches slender; fruit not proliferous 31. O. spinosior

Branches stout; fruit proliferous 32. O. prolifera

Spines white or yellow.

Spines white; petals greenish yellow, 1 cm.

long or less 33. O. alcahes

Spines yellow; petals red, 2 cm. long 34. O. burrageana

30. Opuntia fulgida Engelmann, Proc. Amer. Acad. 3: 306.


Opuntia mamillata Schott in Engelmann, Proc. Amer. Acad.

Opuntia fulgida mamillata Coulter, contr. U. S. Nat. Herb.

Plant sometimes 3 meters high or even more, with a rather definite woody trunk 10 to 20 cm. in diameter, much branched, sometimes almost from the base, and forming a compact flattened crown; terminal joints 10 to 20 cm. long, 3 to 5 cm. in diameter, very succulent, strongly tuberculate, easily breaking off; spines 2 to 12, yellowish to brown, 2.5 to 3.5 cm. long, acicular, covered with loose, papery sheaths; glochids small, whitish to light yellow; flowers light rose, 2.5 to 3 cm. broad; petals few, obtuse; stamens and style very short; fruit at first tuberculate, in age smooth, somewhat pear-shaped, 2 to 5 cm. long, green, usually very proliferous; seeds rather small, 4 mm. broad, often wanting.

Type locality: Mountains of western Sonora, Mexico.

Distribution: Gravelly and sandy situations, southern Arizona, Sonora, and Sinaloa.

We consider O. mamillata as synonymous with O. fulgida; in herbarium and greenhouse specimens we can find no constant differences. Professor J. J. Thornber, who has long studied this group, says there is no difference between the flowers and fruits, and that there is no difference in distribution (Ariz. Agr. Exp. Sta. Bull. 67: 501). In the field, however, one can see two rather distinct forms which differ in armament, the typical plant being the more spiny.

This is one of the most characteristic opuntias of southern Arizona, being very abundant on the valley slopes and lower foothills. It often forms dense colonies almost to the exclusion of other cacti, or it may be associated with other species, especially of Opuntia. It

Fig. 82.—Opuntia molesta.

is a most troublesome plant to come in contact with, for, as the sharp, barbed spines pierce the flesh, the joints easily break loose from the plant and are detached with difficulty from the unfortunate victim.

The flowering season extends from early spring to September. The fruit is markedly proliferous, often developing in chains, and so persisting for several years, possibly eight or ten years, as suggested by Professor D. S. Johnson. They grow in chains of 8 or 9 fruits (i2 to i4 have been reported), several chains hanging from a single joint and forming a large cluster. We have seen as many as 38 fruits (40 to 50 have been reported) in a single cluster, and doubtless under favorable conditions many more would be found. These juicy fruits, usually spineless, are much sought by grazing animals.

According to Professor Johnson, who has studied this species several years, the seeds are not known to germinate in nature. Only by cutting away a part of the hard, bony coat could they be made to germinate in the greenhouse. The species is propagated easily by the terminal joints, which come off readily and are transported far and wide like burs, and soon strike root on reaching the soil. New plants are also started occasionally by the fruits themselves.

This species appears to hybridize with O. spinosior.

Illustrations: Ariz. Agr. Exp. Sta. Bull. 67: pl. 1, f. 2; Bull. Torr. Club 32: pl. 9, f. 1; Cact. Mex. Bound. pl. 75, f. 18; Gard. and For. 8: f. 46; Hornaday, Camp-fires on Desert and Lava opp. p. 42, 320; Lumholtz, New Trails in Mex. opp. p. 18; Monatsschr. Kakteenk. 18: 153; Nat. Geogr. Mag. 21: 710; N. Mex. Agr. Exp. Sta. Bull. 60: pl. 6, f. 2; Plant World 116: f. 1, in part; 1110: f. 9, in part; Sargent, Man. Trees N. Amer. f. 559; Ariz. Agr. Exp. Sta. Bull. 67: pl. 5, f. 1; Cact. Mex. Bound. pl. 75, f. 19; Lumholtz, New Trails in Mex. opp. p. 152; Nat. Geogr. Mag. 21: 710; Plant World 116: f. 1, in part; 1110: f. 9, in part, the last six as Opuntia mamillata; Carnegie Inst. Wash. 269: Frontispiece; pl. 1 to 7; pl. 8, f. 76 to 79; pl. i2.

Plate ix, figure 6, represents the proliferous fruit; plate xii, figure 1, is from a photograph taken by Dr. MacDougal near Tucson, Arizona, showing the typical plant to the left and the less spiny plant to the right.

31. Opuntia spinosior (Engelmann) Tourney, Bot. Gaz. 25: 119. 1898.

Opuntia whipplei spinosior Engelmann, Proc. Amer. Acad. 3: 307. 1856.

Plants 2 to 4 meters high, tree-like in habit, with a more or less definite, woody trunk, openly branched; ultimate joints 1 to 3 dm. long, 1.5 to 2.5 cm. in diameter, often bright purple, strongly tuberculate; tubercles about 6 to i2 mm. long, longer than broad, more or less flattened laterally; spines 6 to 12, but on old branches sometimes as many as 25, 10 to 15 mm. long, divergent, gray to brownish, covered with thin sheaths; glochids yellowish white; flower-buds short, acute; flowers 5 to 6 cm. broad, purple to pink, yellow, or even white; petals about i0, broad at apex, narrowed at base; style thick, cream-colored or pinkish; ovary tuberculate, bearing small, purple leaves and long, white, easily detached bristles; fruit strongly tuberculate, spineless, yellow, globose to broadly oblong, 2.5 to 4 cm. long, with a depressed umbilicus; seeds white, 4 mm. broad, smooth, with a very indistinct marginal band.

Type locality: South of the Gila River.

Distribution: Arizona, western New Mexico, and northern Mexico.

Opuntia spinosior neomexicana (Toumey, Bot. Gaz. 25: 119. 1898) seems to be a yellow-flowered form of this species. Mr. Toumey writes that his original material of this variety came from the low foothills north of the Rillito River near Tucson.

Opuntia spinosior was described by Engelmann in 1856 as a variety of O. whipplei, to which it is only remotely related, but it was not separated until i898, when it was described as distinct by Professor J. W. Toumey.

Illustrations: Ariz. Agr. Exp. Sta. Bull. 67: pl. 1, f. 1; pl. 5, f. 2; Gard. and For. 9: 1; N. Mex. Agr. Exp. Sta. Bull. 60: pl. 7, f. 1; Plant World 1110: f. 7; Sargent, Man. Trees N. Amer. f. 560.

1. Leafy branch of Opuntia imbricata. 2 to 5. Forms of Opuntia alcahes.

1. Flowering branch of Opuntia prolifera. 2 to 5. Opuntia vestita.

(All natural size.)

1. Leafy branch of Opuntia imbricata. 2 to 5. Forms of Opuntia alcahes.

1. Flowering branch of Opuntia prolifera. 2 to 5. Opuntia vestita.

(All natural size.)

Plate x, figures 2 and 3, are from paintings showing different flower-colors, made at the Desert Laboratory, Tucson, Arizona; figure 4 represents a fruiting joint of a plant collected by F. Gilman at Sacaton, Arizona; and figure 5 represents a leaf-bearing joint of the same plant; plate xii, figure 2, is from a photograph of the plant in the Tucson Mountains, Arizona, by Dr. MacDougal.

32. Opuntia prolifera Engelmann, Amer. Journ. Sci. II. 14: 338. 1852.

Stems 1 to 2 meters high, the trunk and old branches terete and woody; terminal joints 3 to 12 cm. long, easily breaking off, fleshy, covered with short, more or less turgid tubercles; spines 6 to 12, brown, 10 to 12 mm. long; glochids pale; flowers small; sepals orbicular, obtuse, dark red; petals red; filaments yellow; style stout; stigma-lobes red; ovary 1 cm. long, strongly tuberculate; upper areoles bearing 2 to 6 reddish spines or the joints naked throughout; fruit proliferous, 3 to 3.5 cm. long and often without seeds; seeds, if present, large, regular, 6 mm. broad.

Type locality: Arid hills about San Diego, California.

Distribution: Southern California and coast of Lower California.

The range of this species is not well known. We have referred here, with some doubt, specimens collected by Dr. Rose on Guadalupe Island, off the coast of Lower California, as well as specimens from the south end of Lower California, but we have seen no flowers from these Lower California collections. A peculiar form less than 5 dm. high with bluish-green joints and small seeds, from near Newport, Orange County, California, deserves further study.

This species, although common in southern California, has never been fully and accurately described. It is often confused in collections with O. serpentina, with which it grows, although they are very different.

In greenhouse specimens the joints and spines are not well developed.

Illustration: Meehan's Monthly 3: pi. 1.

Plate xi, figure 2, represents a flowering joint of a plant collected by E. W. Nelson and E. A. Goldman in Lower California, which bloomed at the New York Botanical Garden in April 1914. Figure 83 represents a joint of a plant sent from La Mortola, Italy, in 1912; figure 84 is from a photograph of this plant.

Of this relationship, but of very different habit, is the species collected by Dr. Rose on West San Benito Island in 1911. Unfortunately no flowers or fruits could be obtained, and hence we have not named it here. It may be briefly characterized as follows:

Opuntia sp.

Low, much branched plants; joints short (10 cm. long), thick, and fleshy; leaves cylindric, 10 mm. long, acute; areoles distant, circular, bearing brown wool, tawny glochids and numerous spines; spines 6 to 8, often 4 cm. long, slender, reddish brown, inclosed in loose, thin, brownish sheaths. Collected by Dr. J. N. Rose on West San Benito Island, off the west coast of Lower California, March 9, 1911 (No. 16043).

33. Opuntia alcahes Weber, Bull. Mus. Hist. Nat. Paris 1: 321. 1895.

Plant about 1 meter high, much branched, very spiny, especially when Fig. 83._Opuntia prolifera.

old; branches terete; spines on young joints about 12, short, covered with white or very pale sheaths; tubercles prominent, diamond-shaped; leaves small, 1 cm. long, terete, somewhat bronzed; sepals small, brownish, closely imbricated, hardly spreading at tips; petals sometimes wanting, or, if present, about 1 cm. long, greenish yellow, obtuse; stamens numerous; stigma-lobes very short, 6 to 8, at first exserted beyond the sepals, yellowish; fruit globular, small, becoming turgid in age, yellowish, more or less proliferous, the umbilicus truncated or slightly depressed.

Type locality: In Lower California.

Distribution: Lower California.

Plate xi, figure 3, represents a leaf-bearing joint of a plant obtained by the same collector on Espíritu Santo Island, Lower California; figure 4 is from a plant sent to the New York Botanical Garden from La Mortola, Italy, in 1906. Figure 85 is from a photograph of a plant collected by Dr. Rose at San Francisquito, Lower California.

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