PROTECTION OF GREEN LEAVES AGAINST ATTACKS OF ANIMALS. 437 



between the teeth of the oxen, torn from the ground, and dropped, so that it forth- 

 with dries up and perishes. I saw thousands of the tufts, which had been rooted up 

 by oxen, lying, dried and bleached by the sun, on the meadows on the Almboden 

 of Oberiss, in the Tyrolese Stubaithal. It must not be supposed that the animals 

 accomplish this clearance of the meadow deliberately; but it may indeed be 

 admitted that they root up the patches of Mat-grass in order thus to obtain the 







Fig. 116. Acanthus spinosissimus. 



enjoyment of the other plants growing between them, and avoid the risk in doing 

 so of wounding their mouths with the pointed Mat-grass leaves. 



A considerable proportion of plants with sharp acicular leaves inhabit steppes 

 specially distinguished by the great dryness of their summer, particularly the 

 elevated steppes of Persia, where they form a remarkable feature of the landscape. 

 This applies most of all to the numerous species of the genus Acantholimon, a 

 group of which, intermixed with spiny Tragacanth bushes, drawn from nature by 

 Stapf, is exhibited in fig. 114. Like gigantic sea-urchins, lying strewn in groups 

 on the sea-bottom, these plants, growing in hemispherical patches, live on the stony 



