464 



ON USEFUL AND 



BOOK I. 



as the horse-chesnut ; in others very small, as in the willow. In 

 some they are covered with a coat of glutinous matter, as those 

 of the horse-chesnut; in others with a dry tegument, as those 

 of the beech. Some buds are of a red colour, as those of the 

 lime ; others are yellow, as those of the willow ; others black, 

 as those of the ash: brown, as in the beech ; or red and green, 

 as those of the common sycamore. 



9. There is an almost infinite variety in the leaves of trees 

 and shrubs. Some are very broad, as the common laurel ; 

 others very narrow, as the larch. There is a medium between 

 these two extremes in the willow and the almond. Some leaves 

 are entire, as the bay ; others serrated, as the cherry ; pinna- 

 tifid, as the acacia, &c. Some leaves are covered with down, 

 as the sea buckthorn; others with wool, as the hoary poplar; 

 others with prickles, as the holly ; others with a glutinous sub- 

 stance, as the gum cut us, &c. Leaves are of all the different 

 shades of green in the summer months ; and of all the different 

 tints of red and yellow in autumn and spring. Some trees re- 

 tain their leaves and colour throughout the whole year, as the 

 pine tribe ; others lose their green colour in autumn, yet retain 

 their leaves all winter, as the beech and the hornbeam in some 

 circumstances. The elm, the ash, and, most other trees, drop 

 their leaves in autumn, and are naked all winter. Leaves have, 

 in general, the same properties as the bark, only in a fainter 

 degree. These are of considerable importance. Those of the 



