MACLOSKIE CACTACE/E. 59! 



Family 74. CACTACE^E. Cactus Family. 



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

 jointed and bearing spines arising from cushions; and flowers 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 i -celled, with parietal placentae. Fruit a 

 'berry. Seeds numerous, with copious or scanty endosperm. 



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







KEY TO THE GENERA. 



i 



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. 



&2. 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. 



cz. 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. CGERULESCENS Salm. 



Erect, attenuate, 8-angled, cceruleous. Costa 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. 



