399 
Dry, rocky ridges, among supporting shrubs, on both sides of the 
Lower Rio Grande. 
Specimens examined: TEXAS (Poselger of 1853): COAHUILA (Siler of 
1889): also cultivated in Goebel’s Gard. in 1859; Mo. Bot. Gard. in 1863; 
Meehan’s Gard. in 1869. 
The most slender of the Hchinocerei, connected with the globose and ovate forms 
through berlandieri and procumbens. Always grows amoung shrubs which support its 
weak and otherwise decumbent stem. The lower part of the stem is scarcely as thick 
as a quill, and the tuberous root is globular, 1 to 3 em. in diameter, 
II, KucrirEus. Stems cylindricai: seeds smooth or pitted: embryo 
curved, 
* Not arborescent. 
+ Tall (6 to 80 dm.), slender: ribs 3 to 7. 
++ Flowers white. 
45. Cereus monoclonos DC. Prodr. iii, 464 (1828), 
Stem columnar, 12 to 30 dm. high: ribs 6 to 8, obtuse, compressed : 
spines short and brownish, radiant, some of them very rigid and 3.5 
cin. long: flowers white, 15 em. long.—Type unknown, 
A West Indian species, extending into llorida. 
Specimens examined: FLORIDA (Curtiss of 1882): also growing in 
Mo. Bot. Gard. in 1893. 
In the Kew Index this species is referred to (. peruvianus,' but we have had no 
opportunity of comparing it with that species. 
46. Cereus marginatus DC, Rey. Cact. 116 (1828), not Salm (1850). 
Stem simple or branching at apex, erect, dark-green, 5 to 7.5 em. in 
diameter: ribs 5 to 7, obtuse, with acute intervals, woolly through the 
whole length on account of the contluent areole: spines 7 to 9, short 
(4 to 6 mm.) and conical, rigid, grayish (younger ones purplish-black, 
the central scarcely distinct from the rest): flower brownish-purple, 
slender-tubular, 3.5 em.long: fruit globular and spiny.—Type unknown. 
From San Luis Potosi southward throughout Mexico. 
Specimens examined: SAN Luts Porost (Weber of 1865; Parry & 
Palmer 275; Parry of 1878; Pringle 2678): also cultivated in Hort. 
Pfersdorff in 1869, 
The stem is often covered with a woody crust, and the woolly confluent areole are 
often double. It is said to be frequently used for hedges in southern Mexico. 
47. Cereus geometrizans Mart. Pfeiff. Enum. 90 (1837). 
Stem erect, simple, bluish, 10 cm. in diameter: ribs 5 to 9 (mostly 5 
or 6), obtuse, repand-tuberculate, with broad intervals and areole 3 to 
3.5 em. apart: spines 3 to 6, unequal, stout, blackish and at length 
ashy; lateral radials longest (8 to 10 mm.), lowest shorter (4 to 6 mm.), 
uppermost 1 or 2 (often wanting) very short (2 mm.), sometimes all very 
short; central solitary, very long and stout, often angular, sometimes 
1 Mill. Gard. Dict. ed, 8, no. 4. 
8898—No. 7-——4 
