114 MB. DAKWIK ON CLTMBIKa PLANTS. 



avoid asking, wtetlier the difference between foliar and axial 

 organs can be of so fimdamental a nature as is generally sup- 

 posed to be the case *. 



We have attempted to trace some of the stages in the genesis 

 of climbing plants. But, during the endless fluctuations in the 

 conditions of life to which all organic beings have been exposed, 

 it might have been expected that some climbing plants would have 

 lost the habit of climbing. In the cases given of certain South 

 African plants belonging to great twining families, which m 

 certain districts of their native country never twine, but reassnme 

 this habit when cultivated in England, we have a case in pomt, 

 In the leaf-climbing Clematis Jlammida^ and in the tendril-bearmg 

 Vine, we see no loss in the power of climbing, but only a remnant 

 of that revohdng-power which is indispensable to all twiners, and 

 is 80 common, as well as so advantageous, to most climbers. In 

 Tecoma radicans, one of the Bignoniaceie, we see a last and 

 doubtful trace of the revolving-power. 



AVitb respect to the abortion of tendrils, certain cultivated 

 varieties of Oucurhita jpepo have, according to Naudinf, either 

 quite lost these organs or bear semi-monstrous representatives of 

 them. In my limited experience, I have met with only one in- 

 stance of their natural suppression, namely, in the common Bean. 

 All the other species of Vicia, I believe, bear tendrils ; but the Bean 

 is stiff enough to support its own stem, and in this species, at the 

 end of the petiole where a tendril ought to have arisen, a small 

 pointed filament ia always present, about a third of an inch in 

 length, and which must be considered as the rudiment of a tendril. 

 This may be the more safely inferred, because I bave seen m 

 young unhealthy specimens of true tendril-bearing plants similar 

 rudiments. In tlie Bean these filaments are variable in shape, as 

 is so frequently the case with all rudimentary organs, being either 

 cylindrical, or foliaceous, or deeply furrowed on the upper surface. 

 It is a rather curious little fact, that many of these filaments 

 when foliaceous bave dark-coloured glands on their lower surfaces, 

 like those on the stipules, which secrete a sweet fluid ; so that 

 these rudiments have been feebly utilized. 



One other analogous case, though hypothetical, is worth giving. 

 Nearly all the species of Lathyrus possess tendrils; but L.nissohd 

 is destitute of them. This plant has leaves, which must have 



Mr. Herbert Spencer has recently argued (« Principles of Biology,' 1865, 

 p. Viet seq.) with much force that there is no fundamental distinction between 

 foliar and axial organs in plants. 



t Annales des Sc, Nat. 4th series, Bot. torn. vi. 1856, p. 31. 



