PAKASITIC PLANTS. G7 



like a plastic body ; for, while the stems of most other plants 

 generally assume a cylindrical form, these wonderful climbers 

 have the peculiarity of divesting themselves of their rind when 

 brought into contact with an extraneous body, and of spreading 

 over it, until they at length enclose it in a tubular mass. When 

 during this process the powers of the original root are weakened, 

 the stem sends forth new props to restore the equilibrium, and 

 thus the parasitic race continually acquires fresh strength, while 

 the incarcerated trunk is stifled and destroyed. 



Several species of fig-trees are peculiarly remarkable for this 

 destructive property, and from the facility with which their 

 seeds take root where there is a sufficiency of moisture to permit 

 of germination, are formidable assailants of ancient monuments. 



In many tropical trees which, struggling for air and light in 

 the dense thicket of the forest, attain a prodigious altitude, or 

 from the colossal expansion of their branches require steadying 

 from beneath, we find buttresses projecting like rays from all 

 sides of the trunk. They are frequently from six to twelve 

 inches thick, and project from five to fifteen feet ; and as they 

 ascend they gradually sink into the bole and disappear at the 

 height of from ten to twenty feet from the ground, a beautiful 

 provision, which effectually protects the trees from the leverage 

 of the crown, by which they would otherwise be uprooted. 



Our annual herbs, which from their inconsiderable height are 

 less exposed to the fury of the wind, naturally require no solid 

 ligneous stem for their support. Many grow under the covering 

 shade of some powerful protector ; while others find adequate 

 powers of resistance in the long and tough fibrous cells with 

 which their stems are furnished. 



The flax and hemp plants of our northern Flora, the Phormium 

 tenax of New Zealand, and the Musacese and Bromeliacea3 of the 

 tropical zone, are peculiarly distinguished by this fibrous texture, 

 which, besides serving for their own preservation, renders them 

 also eminently useful to man. 



Although unable to move from the spot, and thus to avoid by 

 a timely flight the attacks of their enemies, the plants have not 

 been left defenceless against man and the herbivorous animals of 

 the woods. Thus many of our native shrubs are guarded by 

 ramparts of thorns and prickles, but the spines of our hawthorns 

 and bramble-bushes give but a faint idea of the size which these 



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