ECHINOCACTUS, CEREUS, AND OPUNTIA. 
4, ECHINOCACTUS Link & Otto, Verh. Preuss. Gartenb. Ver. 3, 420, 
t. 13 (1827). 
Usually globose, but becoming oblong or even stout-cylindrical, 
mostly with spine-bearing ribs (sometimes represented only by vertical 
or spiral rows of tubercles): flower-bearing areolwe usually contiguous 
to the young spine-bearing areole and just above them, but sometimes 
further removed (connected with them by a short groove), and rarely 
even in the axil of a tubercle: ovary bearing scales which are naked 
or woolly in the axils: fruit succulent or dry: seeds often albuminous: 
embryo usually curved, with more or less foliaceous cotyledons.—A stro- 
phytum Lem, (1839); Gymnocalycium Pfeiff. (1844); Malacocarpus Salm- 
Dyek (1850). 
As the genera of Cactacew have no very definite boundaries it is to be expected 
that Eehinocactus will be found merging into neighboring genera. The mamillate 
forms, such as /, simpsoni, are clearly intermediate between Cactus and Echinocactus, 
but are nearer the latter in what are considered the more essential characters; while 
the oval and cylindric forms look toward certain species of Cereus, though the gen- 
eral globose ontline is well maintained. Inasmuch as the flowers are related to the 
nascent spiniferous areoke the Cactus relationship is with the Coryphanths, among 
which, as has been pointed out, Cactus macromeris has its Echinocactus tendencies. 
The genus Cereus holds the same sort of relationship to the Kumamillarias, the flow- 
ers in both appearing in connection with the mature spiniferous areole. As shown 
recently by W. F. Ganong,! the so-called floriferous and spiniferous areole are sim- 
ply more or less separated regions of a single pulvinus, which appears in its simple 
form in Opuntia. The same observer also calls attention to the occurrence of true 
but minute leaves in Cactus, Pechinocactus, and Cereus, structures which are prominent 
in Opuntia,and have been taken to be a distinguishing mark of that genus.. . 
“Seales of the ovary subulate, copiously woolly in the axils: fruit dry and enveloped in 
wool: spines (wanting in No.7) rigid and annulate, not hooked.—ERIOCARPI. 
+ Ribs 10 to 27, acute. 
1. Echinocactus polycephalus Engelm. & Bigel.; Engelm, Syn. Cact. 276 (1856). 
Globose (15 to 25 em, in diameter) to ovate (25 to 40 em. high, 12.5 
to 25 cm. in diameter) and cylindrical (reaching 60 to 70 em. high and 
about 25 cm. in diameter), profusely branched at base: ribs 13 to 21 
(occasionally 10): spines 8 to 15, very stout and compressed, more or 
less recurved and reddish; radials 4 to 11, comparatively s slender vr (the 
1 Morphologie und Biologie der Cacteen. 
357 
