CACTUS FAMILY 207 



CACTALES CACTUS ORDER 

 CACTACEAE CACTUS FAMILY 



Sepals many, united or separate; grown to the ovary, petals many, in 

 several rows, mostly separate, stamens many, inserted on the throat of the 

 calyx, ovary 1-celled, fruit a berry, mostly fleshy but sometimes . nearly 

 dry; flowers usually solitary, sessile, terminal or lateral; fleshy plants with 

 continuous or jointed stems, the latter often ridged or tubercled; leafless 

 or nearly so, with spines arising from cushions of minute bristles. 



1. Stems jointed, the joints flat or cylindric OPUNTIA 



2. Stems not jointed, but with ridges or nipples 



a. Stems with ribs or ridges 



(1) Flowers greenish to red or purple ECHINOCEREUS 



(2) Flowers yellow ECHINOCACTUS 



b. Stems with nipple-like projections 



(1) Flowers and fruits arising between the 



nipples CACTUS 



(2) Flowers arising from the nipples ECHINOCACTUS 



CACTUS Linne 1753 NIPPLE CACTUS 



(Gr. name of a prickly plant) 



PL 32, fig. 7. 



Sepals many, united into a bell-shaped or funnelform calyx, grown to 

 the ovary, petals in several rows, yellowish-green to purple, ovary smooth, 

 berry ovoid or club-shaped ; flowers borne at the bases of the tubercles ; 

 leaves none ; stems solitary or clustered, globose or ovoid, with tubercles 

 or nipples ; tubercles conic or cylindric, woolly and with clusters of spines 

 at the apex. 



1. Central spine one or none in each cluster; flow- 



ers yellowish-green ; plants single or clustered C. missouriensis 



2. Central spine 3-12 in each cluster; flowers purple C.viviparus 



ECHINOCACTUS Link and Otto 1827 

 (Gr. e chinos, hedgehog, kaktos, cactus) 



Sepals many, united into a tube grown to the ovary, petals numerous, 

 rose, purple to yellow, berry usually covered with scales and tufts of bristles ; 

 flowers borne on tubercles at or near points from which the spines are de- 

 veloped; stems globose, oblong or cylindric, leafless, tubercled; tubercles 

 arranged in straight or spiral rows, often forming ridges. 



