RELATIONS OF FOLIAGE-LEAVES TO ABSORBENT ROOTS. 



97 



of the stem are only erect for about three-quarters of their length; the upper- 

 most third, including the apex, is bent obliquely outwards and downwards. Drops 

 of rain falling on this upper third of a leaf would flow in a centrifugal direction, 

 and do, as a matter of fact, drip down from the apex. Now the leaves in all 



fj 



^' 



Fig. 14.— Irrigation of Kain-water. 

 In Alfredia cermia. 2 in a Mullein ( Verbascum phlomoides). 



these plants are shorter the higher their position upon the stem, so that the total 

 contour of the plant may be described as a slender pyramid. In consequence of 

 this, water dropping from the outward-bent and drooping apices of superior leaves 

 IS arrested by that part of an inferior leaf which shelves towards the stem, and is 

 thereby conducted centripetally. Thus all the rain-water received by a plant 

 of this kind at last reaches the immediate neighbourhood of the tap-root, and is 



