EARLY SPRING 



45 



long as it is folded, is surrounded by a complete protective covering. 

 As the epidermis develops, and the danger of loss by evaporation thus 

 reduced, the leaf straightens itself out, and the hairs either fall or 

 become shrivelled. The leaf of the Wayfaring Tree is protected, 

 while young, by a complete covering of starhke hairs which form 

 a fine felted coat over the whole surface ; and when the epidermis 

 is properly formed, the hairs are all shed. 



Some young leaves 

 are preserved by scaly 

 stipules which sur- 

 round them after they 

 have emerged from the 

 bud ; and as soon as 

 the epidermis is suffi- 

 ciently impermeable 

 the stipules, having 

 done their work, fall 

 to the ground. So 

 great is the shower of 

 these transient struc- 

 tures, in the case of 

 the Oak, Elm, and 

 Lime trees, that the 

 ground is almost com- 

 pletely covered by 

 them. 



Young leaves have 

 yet another way of 

 preventing the evap- 

 oration of their sap, 

 and that is by turning 

 themselves into the erect position so that the warmth of the 

 spring sun has but little effect on them. The young leaves of 

 various grasses turn their apices upwards ; while those of the 

 Horsechestnut, after having lost the protection afforded by the 

 woolly covering and the original folding, turn themselves with 

 their points downwards. Later, when the epidermis is well 

 formed, and the leaves are so far developed that they are capable 

 of utilising the energy of the sun in the performance of their 

 functions, they take up the horizontal position. 



Another interesting matter for spring observation is the relative 



Twig op the ldie m Spring, showing the 

 Deciduous, Scaly Stipules. 



