152 GENERAL BOTANY 



lanate or woolly if they are long and cover the leaf 

 thickly like wool ; 



silky if long and fine and shining like silk ; 



glandular if they make the leaf sticky; 



ciliate if the edge has fine short hairs like cilia. 



Compound words are often used and will be easily 

 understood, as glandular-pubescent, meaning that the 

 hairs are glandular and short, silkily-pubescent, and so 

 on. Ordinary common words are also used as velvety 

 (meaning a soft but shining surface like that of fine 

 velvet). 



Some leaves when held up against the light show 

 numerous white dots, due to globules of transparent 

 oil. Such leaves are gland-dotted. The oil is nearly 

 always scented, and gives a strong smell to the leaf if 

 it be crushed, as the Orange, Eucalyptus and Myrtle. 



The leaf-blade is traversed by veins (vascular 

 bundles) which carry the sap backwards and forwards 

 to every part of the blade, and also serve to stiffen 

 it, for being thin it could not remain flat without 

 this stiffening. 



The way in which the veins run is often very 

 characteristic, serving to distinguish plants and even 

 whole families of plants, and is termed the venation. 

 There are three main types of venation. 



Parallel venation in the leaves of grasses, Bam- 

 boo, Wheat, Paddy and other similar plants, a number 

 of veins enter the blade from the leaf-base, and run 

 more or less parallel to the tip. They are connected 

 by numerous much thinner cross veins which are in 

 comparison quite inconspicuous. This is termed parallel 

 venation. 



