144 PLANT LIFE. 



the root in obtaining water. Besides, as the rain passes 

 over the foliage and stem, part of it is absorbed and the 

 moisture so obtained refreshes the plant. 



Thus, in the Chickweed, a line of hairs occurs along 

 the stem, changing at every leaf-insertion. The rain 

 travels down each pair of leaves and then runs down 

 this line of hairs, these absorbing as much of the moisture 

 as they can en route. Other well-known examples are 

 those of the Ash leaf, which has a deep groove along its 

 stalk in which lie absorbing hairs, of the Blue Gentian, 

 which has deep grooves with similar absorbing threads 

 at the base of every leaf, and the Gean-tree {Prunus 

 avium). This last is very remarkable, as special absorb- 

 ing discs have been produced on the stalk just below 

 the flat green part of the leaf These little glistening 

 discs or dots are generally supposed to suck in the rain 

 as it travels down the leaf, and so to refresh the 

 tissues.^ 



In all the above examples, the rain is intended to 

 travel inwards and refresh a vertically descending root, 

 but in many cases the roots travel horizontally or are 

 widely spreading, and extend just beyond the shade 

 cast by the plant. In such cases the rain is often delib- 

 erately conveyed from leaf to leaf to the very outside of 

 the foliage and there it drips to the ground. This, for 

 instance, is probably the reason of the long drawn-out 

 tips in such leaves as those of the Lime or Elm. The 

 water drains off by these " acuminate " ends, drips to the 

 foliage below, and so passes outwards. About 30°/^ of 

 the rain never reaches the ground as it is absorbed on 

 the way. The Nettle and most Labiatae with pointed 

 or acute leaves allow the rain to pass in the same way 

 to the outside. 



^ Sometimes described as ' ' nectaries " intended to attract ants. 



