THE LEAF 



205 



jmbescerd, if the hair is soft and downy (Gingily), tomentose if 

 rough and wooUj' (iErna lanata), hispid if the hairs are stiff 

 (Ficus aspej;rima). 



(^) As to their texture: succulent = fleshy (Bryophyllum), or 

 coriaceous ^ lesithery (Mango), or membraneous— thin and flexible 

 (Rose), or scarious = thin and dry (stipules of Begonia). 



3. The Arrangement of the Leaves on the Stem is such 

 as to prevent any interference with one another, and thus to 



Fig. 190. —Arrangement of leaves : 1. alternate; 2. decussate; 3. whorled. 



allow free access to both light and air. They are either alternate 

 when they originate singly from the nodes (Shoeflower), or 

 opposite when the leaves are in pairs all up the stem (Tulasi), 

 or ivJiorled if three or more leaves are at a node (Alstonia; Kan. 

 Halemara). Opposite leaves are termed decussate when each 

 pair of leaves is at right angles to the next pair (Labiatse, 

 Acanthacese, Rubiacese). Leaves are said to be bifarious when 

 the leaves are all on the same side of the stem, left and right 

 (Custard Apple). 



