40 CAOTACEOtTS PLANTS. 



from apex to base, upon which are arranged bundles of spines, as in 

 other genera. In height these plants are the giants of their family, 

 some forming in the native habitats enormous columns 40 to 60 feet 

 high, while even in cultivation it is not uncommon to find specimens 

 15 to 20 feet in height. Some are very rapid growers, and make large 

 plants in a few years. Others, again, are so slow in growth that a 

 dozen years seem to make no appreciable difference in their size. There 

 are, however, two very distinct sections or groups of species of the 

 true Cereus, which differ considerably in habit ; one species being dis- 

 tinguished by their erect rigid stems, and the other by the procumbent 

 or trailing slender stems. The plants included in both bear handsome 

 and abundant flowers, but the creeping or trailing forms are the most 

 beautiful, and contain most of the much-famed Night-flowering Cactese. 

 The genus Cereus, however, as now constituted includes a large number 

 of plants which were formerly assigned to jother genera, but which 

 modern botanists consider are entitled to no higher rank than sub-genera. 

 Under the name of Cereus are therefore arranged over two hundred 

 species, natives of tropical America, the West Indies, and Galapagos 

 Islands, from regions differing considerably in temperature, but generally 

 agreeing in the peculiar dry stn ly or rocky nature of the soil they 

 inhabit. 



Hooker and Bentham thus characterise the genus and adopt the follow- 

 ing subgenera as pointed out by Dr. Engelmann :— Calyx tube produced 

 beyond the ovary ; lobes numerous, exterior scale-like, interior elongated, 

 spirally imbricated. Petals indefinite, larger than the calyx lobes, 

 spreading. Stamens numerous ; filaments adnate to the base of the 

 calyx, the inner free. Ovary exserted, scaly. Style filiform. Stigmas five 

 to indefinite. Fruit scaly or tuberculated. Flowers lateral, often 

 nocturnal. 



FcAinoccrcns.^Ca,1yx tube short, sub-campanulate. Stigmas thick, 

 green. Seeds tuberculated. Stem dwarf, often sub-globose. 



Mtcei-eus. — Calyx tube long. Stigmas pale. Seeds smooth, rarely 

 rugose. Stem tall. Spines in flower bearing and sterile parts of the 

 plant not different. 



Lepidocerciis. — Calyx tube short, scaly ; lobes few. Petals fleshy. 

 Stigmas pale. Seeds smooth. Stem tall. Spines of floriferous or sterile 

 fascicles alike. 



Pilocereus, — Calyx tube short, scaly ; lobes few. Stigmas pale. Seeds 

 smooth. Stem tall. Sterile and floriferous fascicles dissimilar. 



Ecliinopsis. — Calyx tube elongated, downy; lobes numerous. Stamens 

 in two series ; the exterior adnate to the calyx tube, inner free. Fruit 

 scaly. Stem depressed, ribbed, globose, or cylindrical. 



