Ohap.l twining plants. 35 



most improbable. It would be hardly possible with 

 any plant which ascended above a few feet in height, 

 or which lived in an exposed situation ; for the stem 

 could be pulled away easily from its support, with but 

 little unwinding ; nor could it have adhered at all, 

 had not the intemodes soon become moderately rigid. 

 With leaf-climbers, as we shall soon see, analogous 

 cases frequently occur ; but these present no difficulty, 

 as the stem is secured by the clasping petioles. 



In the many other revolving and twining plants 

 observed by me, I never but twice saw the movement 

 reversed ; once, and only for a short space, in Ipomaea 

 jucunda ; but frequently with Hibbertia dentata. This 

 plant at first perplexed me much, for I continually 

 observed its long and flexible shoots, evidently well 

 fitted for twining, make a whole, or half, or quarter 

 circle in one direction and then in an opposite 

 direction; consequently, when I placed the shoots 

 near thin or thick sticks, or perpendicularly stretched 

 string, they seemed as if constantly trying to ascend, 

 but always failed. I then surrounded the plant with a 

 mass of branched twigs ; the shoots ascended, and 

 passed through them, but several came out laterally, and 

 their depending extremities seldom turned upwards as 

 is usual with twining plants. Fiaally, I surrounded 

 a second plant with many thin upright sticks, and 

 placed it near the first one with twigs; and now 

 both had got what they liked, for they twined up 

 ■ the parallel sticks, sometimes winding roimd one and 

 sometimes round several ; and the shoots travelled 



