Acanthocereus colombianus sp nov

Erect, branching dichotomously, 2 to 3 meters high; joints about 9 cm. wide, strongly 3-winged; areoles large, 5 cm. apart; radial spines 5 to 8, very short, less than 5 mm. long; central spines 1 or 2, very stout, 4 to 5.5 cm. long; flower 25 cm. long, white, with a rather stout tube 12 cm. long, the gradually expanded throat 5 to 6 cm. long.

Collected by Francis W. Pennell and Henry H. Rusby near Calamar, Colombia, July 10, 1917

z-nt . \ junJUi-lLJC -4-U Fig. 181.—Part of joint of A. horridus. X0.4.

Bonda, Colombia, in 1898-1899 (No. 2423). According to Mr. Smith this species grows in dry forests and thickets at low altitudes; here it is known as pitahaya.* His plant

*Pitahaya is a well-known name in tropical America for many species of cacti, especially of Cereus and its relatives, of which there are various spellings, such as pitajaya, pitajuia, pitalla, pitaya, and pithaya. Several suffixes are sometimes used with it, as pitahaya agre, pitahaya agria, pitahaya de San Juan, and pitahaya dulce, and it has the diminutives pitayita and pitahayita.

comes from near the type locality of Cactus pitaiaya Jacquin, but we refer that species to A. pentagonus, also found in northern Colombia.

The species is near A. horridus, but has a much longer flower-tube.

3. Acanthocereus pentagonus (Linnaeus) Britton and Rose, Contr. U. S. Nat. Herb. 12: 432. 1909.

Cactus pentagonus Linnaeus, Sp. Pl. 467. 1753.

Cactuspitajaya Jacquin, Enum. Pl. Carib. 23. 1761.

Cereuspentagonus Haworth, Syn. Pl. Succ. 180. 1812.

Cactusprismaticus Willdenow, Enum. Pl. Suppl. 32. 1813.

Cereus prismaticus Haworth, Suppl. Pl. Succ. 77. 1819.

Cereus pitajaya De Candolle, Prodr. 3: 466. 1828.

?Cereus undulosus De Candolle, Prodr. 3: 467. 1828.

?Cactus undulosus Kosteletzky, Allg. Med. Pharm. Fl. 4: 1393. 1835.

Cereus cognatus Pfeiffer, Enum. Cact. 106. 1837, as synonym.

Cereus acutangulus Otto in Pfeiffer, Enum. Cact. 107. 1837.

Cereusprinceps Pfeiffer, Enum. Cact. 108. 1837.

Cereus ramosus Karwinsky in Pfeiffer, Enum. Cact. 108. 1837.

Cereus baxaniensis Karwinsky in Pfeiffer, Enum. Cact. 109. 1837.

Cereus variabilis Engelmann, Bost. Journ. Nat. Hist. 5: 205. 1845. Not Pfeiffer, 1837.

Cereus nitidus Salm-Dyck, Cact. Hort. Dyck. 1849. 211. 1850.

Cereus vasmeri Young, Fl. Texas 276. 1873.

Cereus dussii Schumann, Gesamtb. Kakteen 89. 1897.

Cereus sirul Weber in Gosselin, Bull. Mus. Hist. Nat. Paris 10: 384. 1904.

Stem clambering, usually 2 to 3, sometimes 7 meters high, but when growing in the open more or less arched and rooting at the tips, then making other arches and thus forming large colonies; old trunk becoming nearly round, 5 cm. in diameter or more, covered with a thick mucilaginous, spineless cortex and a hard-wood axis with only a small pithy cavity; joints 3 to 8 cm. broad, 3 to 5-angled, low-crenate; juvenile growth nearly terete, with 6 to 8 low ribs, approximate areoles and numerous short acicular spines; areoles on normal branches 3 to 5 cm. apart; spines gray, acicular to subulate, various; radials at first 6 or 7, 1 to 4 cm. long; central spine often solitary, longer than the radials; spines of old areoles often as many as 12, of which several are centrals; flowers 14 to 20 cm. long; tube and ovary bearing conspicuous areoles with brown felt and several subulate spines; outer perianth-segments green; inner perianth-segments white, acuminate: fruit oblong. red, edible: cotyledons broadly ovate, 5 to 8 mm. long, thick, united at base, gradually passing below into the spindle-shaped hypocotyl.

Type locality: America, but no definite locality cited.

Distribution: Keys of southern Florida; coast of Texas. south along the eastern coast of Mexico to Guatemala and

Fig. 182.—Acanthocereus pentagonus.
Fig. 183.—Acanthocereus pentagonus.

Panama; the coasts of Colombia and Venezuela and Guadeloupe. Introduced on St. Thomas and St. Croix. Recorded from Cuba.

As understood by us this species varies greatly in the relative thickness of its branches, in armament, and in the size of its flowers. Its geographical range is, in our conception, greater than that of mot cacti.

Cereus baxaniensis ramosus (Salm-Dyck in Walpers, Repert. Bot. 2: 277. 1843) is published only as a synonym. Cereus arcuatus Zuccarini (Monatsschr. Kakteenk. 14: 55. 1904) from its description is of this relationship. It was originally collected at Totolapa, Mexico, by Zuccarini.

Cereus bajanensis Wercklé (Monatsschr. Kakteenk. 15: 166. 1905) was never described but belongs here. Cereus quadrangularis Haworth (Syn. Pl. Succ. 181. 1812; C. trigonus quad-rangularis Pfeiffer, Enum. Cact. 118. 1837; Cactus quadrangularis Loudon, Encycl. Pl. 412. f. 6876. 1829) may belong here, but Pfeiffer referred it with a question to Cereus caripensis De Candolle (Prodr. 3: 467. 1828; Cactus caripensis Humboldt, Bonpland, and Kunth, Nov. Gen. et Sp. 6: 66. 1823), but this species was referred by Schumann to the genus Rhipsalis.

Acanthocereus
Fig. 184.—Acanthocereus pentagonus in cactus plantation of Charles Deering at Buena Vista, Florida, May 1918.

Cereus undulatus Pfeiffer (Enum. Cact. 107. 1837), based on a specimen in the Dresden Garden, is usually referred to Cereus acutangulus, but was not described by Pfeiffer at the place here cited.

A specimen in the Berlin Garden also was called Cereus undulatus by D. Dietrich (Syn. Pl. 3: 104. 1843) and described, but should be referred elsewhere. It is of quite different relationship, being very slender, dull green, 10-ribbed. The flowers are large, 12.5 cm. in diameter, white. Its native habitat is unknown.

Illustrations: Cact. Journ. 1: 125; Cact. Mex. Bound. pl. 60, f. 5, 6, all these as Cereus variabilis; Monatsschr. Kakteenk. 13: 158; Rev. Hort. Belge 40: after p. 184; Tribune Hort. 4: pl. 140, as Cereus baxaniensis.

Plate xvi, figure 1, shows a flower and part of a joint of a plant sent from the Berlin Botanic Garden to the New York Botanical Garden. Figure 182 is from a photograph

BRITTON AND ROSE, VOL. II

PLATE XVI

M. E. Eaton del. :

taken by Marshall A. Howe on Boot Key, Florida, in 1909; figure 183 shows the fruit and withering perianth of a specimen collected by Dr. Rose at Laredo, Texas, in 1906; figure 184 is from a photograph by J. K. Small of a plant in the cactus plantation of Charles Deering, Buena Vista, Miami, Florida, May 1918, originally brought from Sands Key in 1917.

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