CACTACER. SILVA OF NORTH AMERICA. 53 
CEREUS GIGANTEUS. 
Suwarro. 
FLowers clustered at the top of the stems; calyx-tube short, covered with scales, 
many-lobed. Fruit oval, bursting irregularly into three or four valves; seeds smooth ; 
cotyledons foliaceous, hooked at the apex. 
Cereus giganteus, Engelmann, Hmory’s Rep. 158 (1848) ; 676. — Hemsley, Bot. Biol. Am. Cent. i. 543. — James, 
Am. Jour. Sci. ser. 2, xiv. 3385; xvii. 231; Proc. Am. Am. Nat. xv. 982, f. 3. — Sargent, Forest Trees N. Am. 
Acad. iii. 287; Bot. Mex. Bound. Surv. ii. 42, t. 61, 62; 10th Census U. S. ix. 89. 
Brewer & Watson Bot. Cal. i. 247. — Bigelow, Pacific R. Pilocereus Engelmanni, Lemaire, Jl. Hort. ix. Misc. 97 
Rk. Rep. iv. 12.— Engelmann & Bigelow, Pacijic R. R. (1862). 
Rep. iv. 36. — Walpers, Ann. v. 46. — Lemaire, Ill. Hort. Pilocereus giganteus, Forster, Handb. Cact. ed. Riimpler, 
ix. Mise. 95. — Marcou, Jour. Hort. Soc. France, sér. 2, iii. 662, f. 88 (1886). 
A tree, fifty to sixty feet in height, with a trunk sometimes two feet in diameter, columnar, thickest 
below the middle and tapering gradually and slightly towards both ends, marked by transverse 
superficial lines into rings four to eight inches long, which represent the amount of annual longitudinal 
growth, and branchless or furnished above the middle with a few, usually two or three, stout alternate 
or sometimes opposite upright branches which are shorter but otherwise resemble the principal stem. 
At the base the trunk is eight to twelve-ribbed, with obtuse ribs four or five inches broad separated by 
wide shallow depressions; higher up the stem the ribs are somewhat triangular and rounded or obtuse 
on the back with deep narrow grooves between them; at the top they increase to eighteen or twenty 
by bifurcation or by the growth of new ribs, and are obtuse, deep, and compressed. The stem and 
branches are covered with a thick tough green epidermis, and consist of a fleshy covering and a circle 
of bundles of woody fibre which makes, with annual layers of exogenous growth, dense tough elastic 
columns placed opposite the depressions between the ribs and one half of an inch to three inches in 
diameter ; they are frequently united by branches growing at irregular imtervals between them, and 
increase in thickness towards the base, where they swell into spreading irregular knotted roots. The 
woody frame remains standing after the death of the plant and the decomposition of its fleshy covering ; 
this is three to six inches thick, saturated with bitter juice, and, passing between the woody bundles, 
forms in the centre of the stem a pith four to six inches in diameter. The backs of the ribs, except at 
the base of old trees where they become worn and smooth, are set at distances of half an inch with a 
row of pale elevated chaffy cushions or areolz about half an inch in width and rather more in length, 
from which are developed clusters of stout spines ; these are straight, with dark enlarged bulbous bases, 
and are sulcate and angled, and pale or tinged with red; in the centre of the cluster are six stout 
spines; of these the lower four are horizontal or slightly clined downward, the lowest being the 
longest and stoutest and sometimes an inch and a half long and one twelfth of an inch thick, while the 
upper two are shorter, more slender, and slightly turned upward ; surrounding this central group of six 
is a row of shorter and thinner spreading radial spines, twelve to sixteen in number. The upper radial 
spines, which are sometimes accompanied by a few shorter setaceous spines, and the lower vary from 
one half of an inch to an inch in length, and are much shorter than the lateral radial spines which are 
sometimes an inch and a half long and increase in length towards the bottom of the cluster. The spine- 
clusters and areole fall together from old stems, generally the six central spines falling first, leaving 
the radial spines appressed on the stem. The flowers, which begin to appear on plants twelve to fifteen 
feet high and open from May to July, are produced in great numbers near the top of the stem, each 
