no 



The Plant World. 



spicuoiis of the cacti is the " dildoe " (Cereus Swartzii), a columnar 

 form growing to as much as 20 feet in height, a plant the gross 

 physiology of which is probably, very similar to that of the 

 sahuaro {Carncgiea giganica). The slender cylindrical form 

 Harrisia gracilis {Cereus repandus) is strikingly unlike any of 

 the cacti of the southwestern states, and the frequent Opuntia 

 spinosissima is unique in having its crown of segments elevated 

 upon an extremely spinose stem. Melocactus communis has the 



Fig. 1. 



Coastal Desert near Port Henderson, with the Dildoe (Cereus Swartzii) and species 

 of Acacia and Cassia. 



same form as the American barrel cacti {Echinocacius spp.), and 

 is common, although not so conspicuous as the larger forms. 

 All of the cacti and many of the thorn shrubs of the desert areas 

 are not found outside them in the island, while the ephemeral 

 plants are, so far as noted, species which grow elsewhere in the 

 island and are not at all similar to the hoary and tomentose 

 ephemerals of the continental deserts. 



The alluvial valley which lies between the Healthshire Hills 

 and the central complex of hills that forms the backbone of the 

 island is a savanna region, bordered along Kingston harbor with 

 a swamp made up of the mangroves Rhizophora mangle and Avi- 



I 



