MACLOSKIE CACTACEyE. 591 



Family 74. CACTACE.E. Cactus Family. 



Fleshy, leafless plants (or with small leaves], the stems continuous or 

 jointed and bearing spines arising from cushions ; zndfawers mostly soli- 

 tary, large and showy, sessile, regular, and perfect. Calyx-tube adnate to 

 the ovary, with many calyx-lobes and petals. Stamens numerous, inserted 

 on the tubular axis. Ovary \ -celled, with parietal placentas. Fruit a 

 berry. Seeds numerous, with copious or scanty endosperm. 



Species 1,000, nearly all American, xerophil plants. 



KEY TO THE GENERA. 



A. Not jointed, but angular or fluted or mamillate. Leaves reduced to scales. Flowers sessile 

 on or near areoles. Perianth funnelform to salver-shaped, with a distinct tube. No 

 barbed spines. Seeds mostly pendulous on long funicles. 



b. Stem long, fluted or angled. I. Cereus, p. 591. 



b2. Stem short, globular to clavate, or short-columnar. 



c. Corolla greatly elongated, salver- or funnelform, with gradually widening tube ; arising 



from the older parts of the ridges. 2. Echinopsis, p. 592. 



c2. Corolla shorter, salver- or funnelform. Stem conical or clavate. 



3. Echinocactus, p. 593. 



A2. Jointed ; joints round or flat and leaf-like. Fugacious, cylindric leaves when young. Barbed 

 spines. Seeds with short funicles, which broaden and surround them. Filaments not as 

 long as the rotate corolla. 4. Opuntia, p. 593. 



A$. As Opuntia, but spines not barbed; seeds lens-shaped. 5. Maihuenia, p. 595. 



A^. Jointed ; joints clavate, rounded apically, attenuate basally. Areoles spirally arranged, 

 approximate, small, with scanty wool. Barbed spines in youth. Flowers small, termi- 

 nal. Filaments shorter than the perianth. Seeds winged. 6. Pterocactus, p. 596. 



i. CEREUS Haw. 



Stem short or long, costate on the angles, pulvilligerous with lateral 

 flowers. Calyx-tube prolonged above the ovary, with tomentose pulvilli. 

 Petals many-seriate, exceeding the calyx-lobes, recurved-patent. Stamens 

 free almost as long as the calyx-tube. Ovary exsert, spiny or scaly. 



i. C. COERULESCENS Salm. 



Erect, attenuate, 8-angled, cceruleous. Costce obtuse, scarcely repand. 

 Cushions large, oval, with black tomentum and short, gray wool. Cen- 

 tral spines 3-4, rigid, black; lateral radiant, slender, white, save at 

 extremities. 



