22 O THE CACTACEAE. 



Mammillaria besleri is credited by the Index Kewensis to Link and Otto in Riimpler 

 (Forster, Handb. Cact. ed. 2. 1020. 1885) which is the index of that work where the name 

 Melocactus besleri is intended. 



We have referred to this species the plant collected by Dr. Rose at Joazeiro, Bahia, in 

 1915 (No. 19764), although we are not quite certain of this reference. Dr. Rose found the 

 plant on the dry mesa east of the town. It is deep-seated in the hard ground and appears 

 only a little above the surface. Old plants produce a large white-woolly cephalium from 

 near the center of which the flowers appear. Birds are said to be very fond of the fruit of 

 this plant. 



Illustrations: Nov. Act. Nat. Cur. 16 1 : pi. 16, as Cactus placentijormis ; Nov. Act. Nat. 

 Cur. 18: Suppl. 1. pi. 4, f. 2; Verh. Kon. Akad. Wetensch. II. 5 3 : pi. 1, f. 2, 2a, 2b; Verh. 

 Ver. Beford. Gartenb. 3: pi. 21, as Melocactus besleri; Krook, Handb. Cact. 63; Nov. Act. 

 Nat. Cur. 19: Suppl. 1. pi. 15; Palmer, Cult. Cact. 127; Forster, Handb. Cact. ed. 2. 449. 

 f. 51 ; Pfeiffer, Abbild. Beschr. Cact. 2 : pi. 1, as Discocactus insignis; Besler, Hort. Eystett. 

 4. Ord. f. 1, as Melocactus; Engler and Prantl, Pflanzenfam. 3 6a : f. 64. 



Figure 234 is a reproduction of the first illustration cited above; figure 233 is from a 

 photograph, taken by Paul G. Russell, of Dr. Rose's plant at Joazeiro, Brazil. 



7. Discocactus bahiensis sp. nov. 



Small, about 6 cm. in diameter, somewhat flattened; ribs about 10, but nearly hidden under the 

 mass of spines ; cephalium prominent, made up of a mass of white wool, almost devoid of bristles ; 

 spines 7 to 9, slightly flattened, stout, somewhat curved backward, rose-colored, 1.5 to 3 cm. long; 

 flowers 4 to 5 cm. long with a slender tube; perianth-segments oblong, white, tinged with yellow; 

 fruit a small naked berry; seeds globular, tuberculate. 



Obtained by Dr. J. N. Rose through Dr. Leo Zehntner near Joazeiro, Bahia, Brazil 

 (Rose's No. 19783, type, and No. 19742). 



Somewhat similar to D. zehntneri in size, but with different spines, a more prominent 

 cephalium, and coarser tuberculations on the seeds. 



Plate xxiv, figure 4, shows the type which flowered in the New York Botanical Garden 

 in April 1916. 



2. CACTUS Linnaeus, Sp. PI. 466. 1753. 



Melocactus Link and Otto, Verh. Ver. Beford. Gartenb. 3: 417. 1827. 



Plants solitary or clustered, globular to short cylindric, sometimes depressed, at least when 

 young, 1 -jointed, bearing clusters of spines on the ribs; ribs 9 to 20, mostly straight, rarely spiraled 

 in some individuals ; inflorescence a compact mass of hairs and bristles forming a cephalium borne 

 at the top of the plant, this often very large and elongated; flowers small, pinkish, appearing in the 

 mid-afternoon from the top of the cephalium, tubular-salverform, the few perianth-segments spread- 

 ing; stamens attached near the top of the slender flower-tube; style slender; stigma-lobes linear, 

 few; fruit clavate, naked, red or rarely white; seeds black. 



Type species: Cactus melocactus Linnaeus. 



The terminal cephalium is a woody axis, the wood-elements arranged in interlock- 

 ing spirals, showing a characteristic, complicated pattern, in cross-section, well illustrated 

 in that of Cactus intortus; on this axis the flower-bearing areoles are densely aggregated, 

 spineless, but woolly and often bristly. 



The fruits in this genus are very much alike in shape, varying from white to scarlet, 

 always smooth, naked, and of an agreeable acid taste. They are often eaten in the West 

 Indies being slightly juicy when first ripe. 



About 224 names occur under Melocactus and 282 under Cactus; many of the latter, 

 however, are referable to other genera. We recognize 18 species in the genus Cactus as 

 here circumscribed. 



