CONCLUDING REMARKS. 115 



struck every one who has noticed them with surprise, for they 

 are quite unlike those of all common papilionaceous plants, and 

 resemble those of a grass. In L. aphaca the tendril, which is 

 not highly developed (for it is unbranched, and has no sponta- 

 neous revolving-power), replaces the leaves, the latter in function 

 being replaced by the large stipules. Now if we suppose the 

 tendrils of L. aphaca to become flattened and foliaccous, like the 

 little-rudimentary tendrils of the Bean, and the large stipules, not 

 being any longer wanted, to become at the same time reduced in 

 size, we should have the exact counterpart of L. nissolia, and its 

 curious leaves are at once rendered intelligible to us. 



It may be added, as it will serve to sum up the foregoing views 

 on the origin of tendril-bearing plants, that if these views be 

 correct, L. nissolia must be descended from a primordial spirally- 

 twining plant ; that this became a leaf-climber ; that first part of 

 the leaf and then the whole leaf became converted into a tendril, 

 with the stipules by compensation greatly increased in size*; 

 that this tendril lost its branches and became simple, then lost its 

 revolving-power (in which state it would resemble the tendril of 

 the existing L. apliaca), and afterwards losing its prehensile power 

 and becoming foliaceous would no longer be called a tendril. In 

 this last stage (that of the existing L. nissolia) the former tendril 

 would reassume its original function of a leaf, and its lately largely 

 developed stipules, being no longer wanted, would decrease in size. 

 If it be true that species become modified in the course of ages, 

 we may conclude that L. nissolia is the result of a long series of 

 changes, in some degree like those just traced. 



The most interesting point in the natural history of climbing 

 plants is their diverse powers of movement; and this led me on 

 to their study. The most different organs — the stem, flower- 

 peduncle, petiole, mid-ribs of the leaf or leaflets, and apparently 

 aerial roots — all possess this power. 



In the first place, the tendrils place themselves in the proper 

 position for action, standing, for instance in the Coba?a, vertically 

 upwards, with their branches divergent and their hooks turned 

 outwards, and with the young terminal shoot thrown on one side ; 

 or, as in Clematis, the young leaves temporarily curve themselves 

 downwards, so as to serve as grapnels. 



* Moquin-Tandon (Elements dc Teratologic, 1841, p. 156) gives the case 

 of a monstrous Bean, in which a case of compensation of this nature was 

 suddenly effected; for the leaves had completely disappeared and the stipules 

 had grown to an enormous size. 



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