CACTACEAE. 291 



Order 20. OPUNTIALES. 



Fleshy plants, with continuous or jointed stems, mostly leafless, or with 

 small leaves, generally abundantly spiny, the spines developed from 

 cushions of hairs or bristles (areolae). Flowers mostly solitary and sessile, 

 perfect, regular, showy. Calyx-tube adnate to the ovary, its limb many- 

 lobed. Petals numerous, imbricated in several rows, mostly distinct. Sta- 

 mens numerous, inserted on the throat of the calyx. Filaments filiform; 

 anthers small. Ovary 1-celled; ovules numerous, anatropous, borne on 

 several parietal placentae. Style terminal, elongated; stigmas numerous. 

 Fruit a berry, mostly fleshy, sometimes dry. Seeds smooth, or tubercled, 

 the testa usually crustaceous or bony; endosperm little, or copious. Only 

 one family. 



Family 1. CACTACEAE Lindl. 

 CACTUS FAMILY. 



Characters of the order. About 100 genera and not less than 1000 

 species, natives of America. 



Areoles with spines but without glochides ; corolla not rotate. 

 Plants tall or long, erect or climbing. 



Plants tall, mostly erect, with ribbed, columnar branches. 

 Flowers short-campanulate, the style exserted ; fruit 



smooth. 1. Cephalocerus. 



Flowers elongated-campanulate, the style included ; 



fruit tubercled when young. 2. Harrisia. 



Plants climbing or trailing, with aerial roots ; flowers noc- 

 turnal, large, widely campanulate. 



Joints sharply trigonous ; corolla-tube not woolly. 3. Hylocereus. 



Joints terete, ribbed or 4-8-angled ; corolla-tube woolly. 4. Selcnicercus. 

 Plants globose or ovoid, not more than twice as high as thick. 

 Plants ribbed, surmounted by a woolly cephalium which 



bears the flowers. 5. Cactus. 



Plants with no cephalium, tubercled, the areoles bearing 



spines and flowers. 6. Coryphantha. 



Areoles with or without spines, but with glochides ; corolla rotate. 7. Opuntia. 



1. CEPHALOCEREUS Pfeiffer, Allg. Gartenz. 6: 142. 1838. 

 [PiLOCEREUs Lemaire, Cact. Gen. Nov. & Spec. 6. 1839.] 



Large, simple or branched, erect, columnar cacti, the joints leafless, 

 elongated, ribbed and grooved, the upper areoles often densely lanate or long- 

 bristly. Flowers solitary at upper areoles, nocturnal, fleshy, rather small, the 

 tube short-funnelform or campanulate, the segments not very widely ex- 

 panding; ovary subglobose, naked or bearing a few scales, spineless; style 

 usually short-exserted. Fruit a globose or depressed-globose, smooth berry; 

 seeds small and numerous, black or brown. [Greek, head-Cerews.] Forty 

 species or more, of tropical and subtropical America. Type species: Cactus 

 senilis Haw. 



Flowering areoles with wool as long as the spines or longer ; 



plant pale-pruinose. 1. c. Millspatighii. 



Flowering areoles without wool or the wool much shorter than 



the spines ; plant dull green, not pruinose. 2. C. bahamensis. 



