IN BXTKA-TEOPICAL COUNTRIES. 257 



Populus tremuloides, Michaux. 



The North American Aspen. Height, 50 feet. It extends 

 west of California, where a particular species, P. trichocarpa 

 (Torrey), occurs. All Poplars might be planted, like all Wil- 

 lows, in gullies, to intercept forest fires; also generally on 

 river banks. 



Portulacaria Afra, Jacquin. 



South Africa. Called Spekboorn. Affords the principal food 

 for elephants ; thus this succulent shrub may deserve natural- 

 isation on stony ridges and in sandy desert land, as likely 

 noui'ishiug to sheep. 



Pouzolzia tuberosa, Wight, 



India. The turnip-shaped root of this herb is edible. The 

 plant may prove hardy. 



Prangos pabularia, Lindley. 



Plateaux of Mongolia and Thibet. A perennial fodder-herb, 

 much relished by sheep, eligible for cold and arid localities 

 and deserving naturalisation on Alpine pasture-grounds. Other 

 perennial species exist near the Mediterranean Sea, on the 

 Atlas, the Caucasus, and the Indian highlands. P. pabularia 

 is regarded by some as the Silphium of Arrianus. 



Pringlea antiscorbutica, W. Anderson and R. Brown.* 



The Cabbage or Horse-radish of Kerguelen's Island. The 

 perennial long roots taste somewhat like horse-radish. The 

 leaves in never-ceasing growth are crowded cabbage-like into 

 heads, beneath which the annual flower-stalks arise. The 

 plant ascends mountains in its native island to the height of 

 1,400 feet, but luxuiiates most on the sea-border. To arctic 

 and other antarctic cduntries it would be a boon. Probably 

 it would live on our Alps. Whalers might bring us the roots 

 and seeds of this remarkable plant, which seems to have never 

 entered into culture yet. The plant was used by the celebrated 

 Captain Cook and all subsequent navigators, touching at 

 yonder remote spot, as cabbage, and it proved to possess power- 

 ful properties against scurvy. Dr. Hooker observes that 

 Pringlea can sectionally be referred to Cochlearia. The whole 

 plant is rich in a pungent volatile oil. Through culture im- 

 portant new culinary varieties may likely be raised from this 

 plant. The taste of this vegetable in its natural growth is like 

 mustard and cress, and the Kerguelen's Land Cabbage, when 

 boiled, proved a wholesome and agreeable substitute for the 

 ordinary cabbage. 



