THE SPECIES OF CACTI COMMONLY CULTIVATED UNDER THE 
GENERIC NAME ANHALONIUM. 
BY CHARLES HENRY THOMPSON. 
Diversities of opinion are so prevalent as to just what 
plants should be included in this group, as well as to 
the validity of a generic separation of the two forms from 
Mamillaria and Echinocactus respectively, that naturally 
much confusion has arisen. The object of this paper is 
not so much an attempt at a monograph as it is to bring 
together the literature of the various species, with illustra- 
tions of each, photographed from living plants, and in 
addition to give such notes as I have taken in my observa- 
tions and studies of the plants grown in the Missouri 
Botanical Garden. 
I shall treat the group as being made up of two distinct 
genera, in that respect following Coulter’s revision of the 
order. 
ANALYTICAL KEY. 
I. Tubercles evident, the exposed surface triangular in outline; the 
epidermis cartilaginous in texture. ARIOCARPUS. 
Upper surface of the tubercles with a longitudinal wool-bearing 
groove along the median line. 
Upper surface of tubercles strongly and irregularly fissured, 
11-13 mm. long by 1.5-2.5 cm. broad. A. fissuratus. 
Upper surface of tubercles flat and finely papulose, about one 
cm. broad and half as long. A, Kotschubeyanus. 
Upper surface of tubercles not grooved. 
Tubercles reflexed and closely imbricated, giving a flat sur- 
face to the top of the plant. Upper surface slightly wavy 
to wrinkled, tinted with dull reddish-brown. 
A. furfuraceus. 
Tubercles more open, squarrosely spreading, more elongated, 
gray-green. A. retusus. 
II. Tubercles scarcely evident; ribs quite prominent: plants decidedly 
succulent; epidermis flexible. LOPHOPHORA. 
Ribs commonly 8, quite regular. L. Williamsii. 
Ribs commonly J3, irregular to much broken. L. Lewinii. 
(127) 
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