LEAVES. 203 



gardening. Barren and thin soils are best suited to the 

 wide spreading roots, which creep extensively on the surface ; 

 dry and sandy plains are adapted to those which penetrate 

 deep for nourishment, and are supplied with bulbs for its 

 preservation, or with downy radicles for its abundant ab- 

 sorption. 



Linnaius enumerates seven kinds of trunks, stems, or 

 stalks of vegetables. These are necessary to be known for 

 botanical distinctions, though some are more important than 

 others. 



About midsummer the progress of vegetation seems to be 

 suspended, and for several days the vital energies of the tree 

 are exerted in the formation of buds. We no longer observe 

 the vigorous growth of spring, but if we examine the young 

 branches, we shall find the newly formed buds at the base 

 of the leaf-stalk, immediately above the place of their inser- 

 tion. After the fall of the leaves they are more conspicuous, 

 and during the winter we may perceive a gradual enlarge- 

 ment, corresponding to the developement of the tender germs 

 which they enclose. Plants, as is well known, may be pro- 

 pagated by buds, and in that sense each bud is a separate 

 being, or a young plant in itself; but such propagation is only 

 the extension of an individual, and not a rc-production of the 

 species, as by seed. 



Leaves are eminently ornamental to plants from their pleaa* 

 ing colour, and the infinite variety as well as elegance of 

 their forms. Their different situations, insertions, forms, 

 and surfaces, which are of the greatest possible use in sys- 

 tematical botany, cannot here be described. A knowledge 

 of their real use with regard to the plant is a curious branch 

 of vegetable physiology. That leaves give out moisture, or 

 are organs of insensible perspiration, is proved by the simple 

 experiment of gathering the leafy branch of a tree, and im- 

 mediately stopping the wound at its base with wax to pre- 

 vent the effusion of moisture in that direction. In a very 

 short time the leaves droop, wither, and are dried up. If the 

 same branch, partly faded, though not dead, be placed in a 

 very damp cellar, or immersed in water, the leaves revive, 

 by which their power of absorption is also proved. A know^- 

 ledge of the perspiring and absorbing power of leaves is often 

 of great practical importance. It teaches us that plants 

 droop, in consequence of the excess of the former, and are 



|tt. 



