52 



SAGACITY AND MORALITY OF PLANTS. 



Fig. i6. — Yellow '.Vetch {Lathynis aph- 

 acd), showing leaf-like stipules (j), and 

 true leaves converted into tendrils (f). 



little more on one side than the other. This twining 

 habit, however, does not manifest itself until the 

 plant has grown for some time. At first the stem 



is erect, and puts forth 

 its leaves at the joints, 

 or nodes, in the ordinary 

 way ; but when it has de- 

 veloped two or three 

 such joints all its natural 

 erectness gradually leaves 

 it. The spaces between 

 the next joints grow 

 faster, and more un- 

 equally, so as to cause the stem to curl and revolve. 

 Of course the amount and rapidity of this curve will 

 be proportionate to the unequal growth. The plant 

 appears as if it were feeling for something to twine 

 round, and when it has found such an object it at 

 once begins to clasp it. The habit of growing erect 

 at first, even among such confirmed twining plants as 

 the Honeysuckle, Tropaeolum, and Hop, etc., plainly 

 shows us that twining has been gradually acquired. 

 All sorts of plants alike have adopted the practice, 

 even Ferns and Adder's-tongues ; for it is highly 

 developed in the well-known Lygodmm, and is also 

 indulged in by Ophioglossuin japoniciniiy which latter 

 climbs by means of its twining leaf-stalks. The habit 

 is indulged in in varying degrees. Some plants 

 only occasionally require it, such as the Bitter-sweet 



