29 



leaves are usually of some shade of green and the lower sur- Colour, 

 face is frequently paler than the upper. The colour of young 

 leaves is sometimes characteristic and is often of some shade 

 of red or purple. As examples we may note the pinkish, or 

 purplish, young leaves of Quercus incana, the bright red ones 

 of Acer caesium, the beautiful purple and brown of those of 

 Mango and the dark red brown of Cassia Fistula. Mature 

 leaves frequently undergo a striking change of colour before 

 they fall off the plant. Such colours are usually called 

 autumn tints and often enable the Forester to recognise his 

 trees from a long distance. As examples we may note : 



The yellow of Odina Wodier, the pale leather-brown of 

 Lagerstrcemia parviflora, the brick -red of Antidesma diandrum, 

 the beautiful red, purple, and orange of Sapium sebiferum, and 

 the dark red, or bronze, of Anogeissus latifolia. Some leaves, 

 on drying, undergo a characteristic change of colour ; those of 

 Dalbergia paniculata turn black and those of many species of 

 Symplocos turn bright yellow. 



Many leaves have a strong and characteristic smell especially Smell, 

 when they are crushed. As examples may be noted the un- 

 pleasant smell of leaves of Viburnum foetens, Premna latifolia 

 and Solanum verbasci folium, the aromatic odour of those of 

 Skimmia Laureola and Cinnamomum Tamala, the black-cur- 

 rant-like smell of Pogostemon plectranthoides and the well-known 

 smell of TJiymus Serpyllum. 



The taste of leaves is also often peculiar. The leaves of Taste - 

 Eauhinia malabarica, Acacia pennata and Antidesma dian- 

 drum, for example, have a characteristic acid taste. 



Leaves which are strongly aromatic frequently have the Glands, 

 ethereal oil, to which the smell is due, stored in small recep- 

 tacles called glands in the leaf tissue. Such glands, being 

 translucent, are easily seen when the leaf is held up to the 

 light as pale spots. Such leaves are said to be gland-dotted. 

 As examples may be taken a leaf of the Orange, or of Zan- 

 thoxylum alatum. 



The texture of leaves, as well as excrescences, such as 

 hairs, scales and so on, which commonly appear on other parts 

 of the plant besides the leaves, will be considered later, when 

 the detailed account of each member has been completed. 



27. The principal points to be pjf rs of 

 paid attention to as regards the petiole of the leaf are its 

 length y which varies greatly in different plants, and its gen- 

 eral shape. In some plants it is very slender and thread-like 

 and is said to be filiform, in others it is stout. Like the 



