CACTUS FAMILY. 153 



$ 2. Tube formed of (lie united sepals, $c. more or less extended beyond the ovary. 



* Stems and branches of flat and leaf -like joints, with the margins more or lexs toothed 



w crenate, and with an evident woody centre or midrib, with no prickles and 

 no bristles, or only tufts of very short ones in the notches. 



2. EPIPHYLLUM. Joints of the branches short and truncate, very smooth, and 



flowering from the end. Flowers open in the daytime and for several days, 

 mostly oblique, the tube not much lengthened; the sepals and petals rose-red, 

 rather few, the innermost and larger ones about 8. Stamens not very many. 

 Stigmas erect or conniving. 



3. PHYLLOCACTUS. Leaf-like branches or joints long, arising from the side of 



older ones, which with age form terete stems. Flowers from the marginal 

 notches, slightly if at all irregular. Stigmas slender and spreading. 



* * Stems or branches 3 - many-angled or grooved, or terete, and with tubercles or 



woolly tufts bearing a cluster of spines, prickles, or bristles. 



4. CEREUS. Stem mostly elongated, rarely globular, regularly ribbed or angled 



lengthwise, and with the clusters of spines or bristles on the ridges one 

 above the other. Flowers from the side of the stem, commonly with a 

 conspicuous tube, which, with the ovary below, is beset with scale-like 

 sepals and generally with woolly or bristly tufts in their axils. Petals 

 numerous and spreading. 



5. ECHINOCACTUS. Stem globular, depressed, or sometimes oblong-club-shaped, 



with many ribs or ridges bearing clusters of spines one above the other. 

 Flowers naked at the summit of the ridges, and with a short or very short 

 tube: otherwise as in Cereus. 



6. MELOCACTUS. Stem globular with a broad base, or conical, with many ribs 



bearing clusters of spines as in Echinocactus; but the flowers small and im- 

 mersed in a woolly cylindrical muff-like mass at the summit. Sepals and 

 petals united in a cylindrical tube, which is often swollen at the base. Fila- 

 ments short. Ovary and berry not scaly. 



7. MAM1LLARIA. Stems globular or cylindrical, mostly tufted, not ribbed, cov- 



ered with distinct and strongly projecting nipple-shaped tubercles, which are 

 arranged in spiral order and tipped with a cluster of prickles. Flowers from 

 the axils of the tubercles, with a short tube. Ovary and berry not scaly. 



1. OPUNTIA, PRICKLY-PEAR CACTUS, INDIAN FIG, &c. (An 



ancient name, transferred to these American plants.) Fl. summer. Fruit 

 often eatable. 



1. Stamens not longer than the roundish, in ours yellow, widely opening petals. 

 # Low, prostrate or spreading, native species, also cultivated. 



O. Vlllgaris, COMMON PRICKLY-PEAR. On rocks and sand, from coast 

 of New England S., with pale and rounded-obovate flat joints, 3' - 6' long, 

 bearing minute appressed leaves, having bristles but hardly any spines in their 

 axils, and a nearly smooth eatable berry. 



O. Rafinesquii. Common W. & S. W. : deeper green, with joints 4' -8' 

 long, the little leaves spreading, several small spines and a single stronger one 

 in the clusters, and flower often with a reddish centre. 



O. Missouri6nsis. From Wisconsin W. on the plains : Avith obovate 

 joints 2' -4' long and tubercled, tufts of straw-colored bristles and 5-10 long 

 and slender spines ; the berry dry and prickly. 



O. Pe8-C6rvi. On the coast S., with small and narrow, almost cylindri- 

 cal, easily separable joints, their spines in pairs ; the berry small and bristly. 



* * Erect, shrubby or tree-like, cultivated in conservatories, from West Indies and 

 South America : berry edible. 



O. Ficus-Indica. Joints obovate, thick and heavy, 1 long, with minute 

 spines or none ; berry obovate, bristly. 



O. Tuna. Joints oval, 4' -8' long, with several unequal spines in the tufts, 

 the longer ones about 1' long. 



O. Brasiliensis. Tree-like, with a round straight trunk rising 10 or 

 more high, bearing short branches, their ultimate joints obovate or oblong, 

 sinuate, thinner and more leaf-like than in the others, armed with single long 

 and very sharp spines. 



