22 CAN PLANTS FEEL? 



diverged, the patient explorer may trace them to a 

 common source. 



When it is considered how sensitive all the more highly 

 organised plants are to light, it will be heard with no 

 surprise that a German botanist, Professor Haberlandt, 

 claims to have identified four different organs in plants 

 which are sensitive to touch, and that these are closely 

 analogous to the organs of touch in animals namely, 

 sensitive spots, bristles, hairs, and papillae. The spots 

 occur on the tips of tendrils, in the same position and 

 answering the same purpose as the sensitive tentacles 

 of zoophytes. Charles Darwin has recorded how the 

 tendril of a passion-flower responds to the gentlest touch 

 of a finger by curling round it, and straightens itself out 

 again when the finger is removed. 



One must not interpret as caused by sensation purely 

 mechanical movements like those of the blue sage 

 (Salvia patens) of our greenhouses and gardens. A native 

 of Mexico, its structure is adapted for the visits of 

 humming-birds, which hover before the flower and insert 

 their delicate bills into its narrow throat to extract the 

 honey from nectaries at the base of the style. In so 

 doing they touch a simple lever near the base of the 

 anthers, which descend smartly from the upper lip of the 

 flower, discharge their golden pollen on the intruder, and 

 return to their place when he withdraws. The bird flies 

 off to another flower, where the process is repeated, and 

 cross-fertilisation ensues. Anybody can make the flower 

 go through this performance by thrusting a stem of grass 

 into its throat. But hi the flowers of every species of 

 barberry or mahonia, a similar movement is the result 

 of sensation. The stamens are very irritable, closing up 



