Pachycereus chrysomallus Lemaire Britton and Rose Contr U S Nat Herb 12 421 1909

Pilocereus chrysomallus Lemaire, Fl. Serr. 3: under pl. 242. 1847.

Cereus chrysomallus Hemsley, Biol. Centr. Amer. Bot. 1: 541. 1880.

Cephalocereus chrysomallus Schumann in Engler and Prantl, Pflanzenfam. 36a: 182. 1894.

Pilocereus fulviceps Weber in Schumann, Gesamtb. Kakteen 176. 1897.

Cereus fulviceps Berger, Rep. Mo. Bot. Gard. 16: 64. 1905.

Stem columnar, massive, at first simple, but in very old plants much branched, giving off hundreds of erect branches which form an almost compact cylinder up to 5 meters in diameter, becoming 12 to 18 meters high; branches glaucous green, 11 to 14-ribbed; flowering branches

BRITTON AND ROSE, VOL. II

PLATE XI

Top of flowering plant of Pachycereus chrysomallus. (Natural size.)

capped by dense masses of brownish wool; areoles approximate or even confluent; radial spines about 12, slender; centrals 3, 1 very long, sometimes 12 to 13 cm. long; flowers borne near the tops of the stems or branches, 6 to 7 cm. long; the bud, afterwards the flower, and finally the fruit, completely concealed in the long wool; ovary covered with small, pale, imbricated scales; flower-tube also covered with imbricated scales, but these larger and pinkish, pointed; flowers doubtless opening at night, but still expanded at 8 o'clock in the morning; tube proper 10 mm. long or less; throat funnelform, 3 cm. long; inner perianth-segments numerous, 1.5 to 3 cm. long, cream-colored; inner perianth-segments and stamens inflexed after anthesis, with the stiff outer perianth-segments pressed down upon them; stamens attached all over the throat, the innermost and lower row united at base and appressed against the style; filaments cream-colored; style stout, stiff, 7.5 cm. long, cream-colored; stigma-lobes linear, erect, cream-colored.

Fig. 107.—Pachycereus chrysomallus.

Type locality: Mexico.

Distribution: Puebla and Oaxaca, Mexico.

This is one of the characteristic plants on the mesas around Tehuacan. When fully grown, it is a very large plant with many upright branches; the trunk and old branches are stout and woody, making it very difficult to obtain botanical specimens. In 1906 Dr. MacDougal and Dr. Rose shipped a very large plant to the New York Botanical Garden, which flowers annually and from which an abundance of flowers has been obtained.

Cereus militaris Audot (Rev. Hort. II . 4: 307. 1845) and Pilocereus militaris (Salm-Dyck, Cact. Hort. Dyck. 1849. 40. 1850, as synonym) probably belong here.

Illustrations: Contr. U. S. Nat. Herb. 10: pl. 18; MacDougal, Bot. N. Amer. Des. pl. 16; Nat. Geogr. Mag. 21: 699, as Pilocereus fulviceps; Contr. U. S. Nat. Herb. 12: pl. 66.

Plate xi illustrates the top of a flowering plant in the New York Botanical Garden brought from Tehuacan, Mexico, by Dr. MacDougal and Dr. Rose in 1906. Figure 107 15 from a photograph taken by Dr. Rose near Tehuacan, in 1906; figure 108 shows the flower of this plant; and figure 109 a longitudinal section of the flower.

7. Pachycereus marginatus (De Candolle) Britton and Rose, Contr. U. S. Nat. Herb. 12: 421. 1909.

Cereus marginatus De Candolle, Mem. Mus. Hist. Nat. Paris 17: 116. 1828. Cereus gemmatus Zuccarini in Pfeiffer, Enum. Cact. 96. 1837.

Fig. 108.—Flower of P. chrysomallus. X0.7. Fig. 109.—Longitudinal section of flower of

P. chrysomallus. X0.7.

Fig. 108.—Flower of P. chrysomallus. X0.7. Fig. 109.—Longitudinal section of flower of

P. chrysomallus. X0.7.

Stems 3 to 7 meters high, erect, usually simple; ribs 5 or 6 (7 in the original specimen), somewhat acute when young, obtuse in age; areoles close together, usually confluent, their wool forming a dense white cushion along the ridge of each rib; spines at first 5 to 8 (1 central), in old areoles more numerous, 1 cm. long or less, but in flowering areoles often numerous, bristly and 2 cm. long; flowers and fruit usually closely set, one above the other, apparently only one at an areole, but recorded as often geminate, and appearing anywhere along the ribs from the top downward; flower funnelform, 3 to 4 cm. long including the ovary; tube and ovary more or less scurfy and with ovate scales subtending bunches of wool and small spines; fruit globular, about 4 cm. in diameter, not very fleshy, yellowish red within, covered with spines and wool which finally drop off; seeds numerous, black, and somewhat shining, rather large, 4 mm. long, the hilum depressed.

Type locality: Mexico.

Distribution: Hidalgo, Queretaro, and Guanajuato, and widely planted and naturalized throughout Mexico.

This species is commonly cultivated throughout central and southern Mexico as a hedge plant and when properly cared for forms an impenetrable barrier; it is there called organo.

Cereus cupulatus, Cereus incrustatus, and Cereus mirbelii are all referred by Pfeiffer (Enum. Cact. 97. 1837) to this species. Cereus incrustans Steudel (Nom. ed. 2. 1: 334. 1840) was only a garden name but was referred to this species by Steudel.

Illustrations: Contr. U. S. Nat. Herb. 5: pl. 59, 60; Bull. Soc. Acclim. France 52: f. 8; Monatsschr. Kakteenk. 19: 62; Reiche, Veg. Alred. Cap. Mex. f. 21, 22; Schumann, Gesamtb. Kakteen f. 17; U. S. Dept. Agr. Bur. Pl. Ind. Bull. 262: pl. 6; Journ. Intern. Gard. Club 3: 18, all as Cereus marginatus; Monatsschr. Kakteenk. 23: 149, as Cereus marginatus gibbosus; Cact. Journ. 1: 59; 2: 169, as Cereus gemmatus; Schelle, Handb. Kakteenk. f. 22, as C. marginatus gemmatus.

Fig. 110.—Flower of P. marginatus. Natural size.

Fig. 110.—Flower of P. marginatus. Natural size.

Figure lio shows a flower drawn from an herbarium specimen collected by Edward Palmer at San Luis Potosí, Mexico, in 1905; figure 111 is from a photograph of the plant used as a hedge near the City of Mexico.

Fig. 111.—Pachycereus marginatus used as a hedge plant in Mexico.

8. Pachycereus ruficeps (Weber).

Pilocereus ruficeps Weber in Gosselin, Bull. Mus. Hist. Nat. Paris 11: 509. 1905.

Cereus ruficeps Vaupel, Monatsschr. Kakteenk. 23: 27. 1913.

Stout, columnar, 1 meters high, from a simple trunk, 3 to 4 dm. in diameter, but branched above; branches erect; ribs about 26; young spines all reddish; radial spines 8 to 10, about 1 cm. long, rigid, grayish; central spines 1 to 3, the longest 4 to 5 cm. long, porrect or deflexed; flowers at the top of the plant, campanulate, 5 cm. long, the ovary and tube bearing small chartaceous scales, these with small tufts of felt and a few yellow bristles in their axils; stamens numerous, arranged in 2 series; style stout, light flesh-colored; stigma-lobes 7 to 9; fruit small, not edible; seeds small, brownish, shining.

Type locality: Near Tehuacan, Mexico.

Distribution: Oaxaca, Mexico.

This species has been described rather fully by Roland-Gosselin, but we are still in some doubt as to its relationship.

Dr. Rose collected flowers of it in 1905, but these were confused with specimens of Cephalocereus macrocephalus, which seems to indicate that the two species grow together.

When Dr. Rose was at the Museum of Paris in 1912 he was given a flower from the type collection made by M. Diguet.

Illustration: Bull. Soc. Acclim. France 52: 58. f. 17, as Cereus ruficeps.

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