FREAKS OF PLANT LIFE. 



South Africa, 1 of which Dr. John Shaw has given a 

 graphic account, the modifying influence being in 

 this case the introduction of the Merino sheep. After 

 alluding to the introduction of a noxious bur-weed 

 (Xanthium spinosuni), he says that when these 

 sheep were first introduced they fed mainly on grasses, 

 but in a country with periodical rains and a high sun 

 these plants had to give way and succumb. Shrubby 

 plants were not eaten as long as the -grass was 

 prominent. But the grass vanished rapidly, and the 

 scrub came to be the main resource of the flocks, and 

 the ground was given over to bush, and scrub, and 

 obnoxious herbs. The climate then became affected, 

 the hardy plants of the southern desert tracts spread 

 northward, and the pleasant country was rapidly 

 becoming an extension of dreary, scrubby, half- 

 deserted Karoo. " Some tracts of the country," he 

 says, " are poisoned by the extraordinary increase of 

 the Tripteris flexnosa, and transport riders, with their 

 oxen, our only carrying power, have to travel through 

 certain parts without pausing, on account of the 

 Melicm, grasses which have increased to an extent 

 scarcely to be fancied in the last few years, and on 

 eating which cattle become affected with intoxication 

 to an alarming extent." This is only one example, 



1 On the changes going on in the Vegetation of South Africa, 

 1 "Linnean Journal," vol. xiv. (1874), p. 202. 



