CORKSCREW SPIRALS 



of the root (see p. 89), the Sensitive Plant, the Monkey 

 and Barberry flowers, are all well-known cases. 



So that it is difficult to find anything in science to con- 

 tradict the comfortable belief that wide-open flowers and 

 stretched-out leaves of plants as they drink in the warm rays 

 of the sunlight are really enjoying themselves, whilst they 

 are doing their day**s work. 



All these interesting facts are so beautifully described and 

 so carefully summed up by Charles Darwin, that we shall 

 only earnestly recommend our readers to get first that fas- 

 cinating book The Power of Movement in Plants^ and then 

 read all the rest of his works.^ 



There are an extraordinary number of these plants and 

 the tendrils are formed exactly where they will be most 

 useful. Every part of a leaf may become a tendril. The 

 whole leaf is changed into one in some kinds of Lathyrus. 

 In a very beautiful creeper which is not so often grown in 

 greenhouses as it might be (Ghriosa superba), the tip of the 

 leaf only acts as a tendril. Leaflets are often made into 

 tendrils. The Clematis is the most economical of them all, 

 for the leaf-stalk coils round and forms little woody rings 

 which hold up the plant. 



Before leaving the subject of tendrils, it may be interest- 

 ing to notice the queer corkscrew spirals in which they roll 

 themselves up. These spirals are formed after the end of the 

 tendril has tied itself to the support and become woody. 

 The free part between the end and its own stem goes on 

 revolving ; now if you tie a piece of string at both ends and 

 make it revolve, you will see at once that it must coil itself 



1 For the above facts : Pfeffer, Pjlanzen-Physiologie, vol. 2, pp. 423-8 ; 

 Green, Vegetable Physiology, p. 3S9 ; Kerner, I.e., p. 697; Bonnier, I.e., 

 p. 305. 



322 



