25 



An ovate leaf which is cordate at the base and pointed at 

 the apex is called a cordate leaf ; similarly a leaf which is 

 sagittate, or hastate, at the base and pointed at the apex is 

 called a sagittate, or hastate, leaf. If in a lanceolate, ovate, 

 or cordate leaf we imagine the petiole to be attached to the 

 apex instead of to the base, we get an ob-lanceolate, ob-ovate, 

 or ob-cordate leaf, respectively. 



A peltate leaf is one in which the petiole instead of being 

 attached to the margin of the leaf-blade is joined to some part 

 of its under-surface, so that the leaf-blade is more or less at 

 right-angles to the petiole, as in Nelumbium speciosum. 



If in a deeply cordate leaf we imagine the basal lobes to 

 grow together and join in front of the petiole we get a peltate 

 leaf ; if now such a cordate leaf was sessile on the stem and the 

 same thing happened, the stem would appear to pass through 

 the leaf. Such a leaf is said to be per/oliate and the base 

 of the leaf which thus embraces, or clasps, the stem is said 

 to be amplexicaul. If the base only partly surrounds the stem 

 it is semi-amplexicaul. Occasionally the bases of two opposite 

 sessile leaves grow together and are then said to be connate. In 

 some cases the leaf-blade is continued along the stem below 

 the leaf insertion and the leaf which thus seems to run down 

 the stem is called decurrent, as seen in Verbascum Thapsus. 

 Pinnately and palmately compound leaves are usually known 

 as pinnate and palmate leaves, respectively. 



The prolongation of the petiole of a pinnate leaf, which 

 corresponds to the midrib of a pinnately-veined simple leaf, is 

 called the rhachis. 



When the rhachis terminates in an odd leaflet the leaf is 

 said to be impari , or odd pinnate and when there is no termi- 

 nal leaflet it is pari , or abruptly pinnate. 



The leaflets of a pinnate leaf are usually opposite to each 

 other in pairs, but sometimes they are alternate on the rhachis. 

 The impari-pinnate leaves of Sissoo have alternate leaflets. 

 When the leaflets of a pinnate leaf vary greatly in size the 

 leaf is interruptedly-pinnate. When the terminal leaflet or 

 pair of leaflets is largest, those below it gradually decreasing 

 in size with the smallest at the base, the leaf is lyrately pinnate, 

 as are the leaves of Picrasma quassioides. 



W T hen the rhachis of a pinnate leaf, instead of giving rise 

 directly to leaflets, develops branches on which the leaflets 

 are borne, these branches are termed pinnae and the whole 

 leaf is said to be bi-pinnate, such as are the leaves of Khair 

 (Acacia Catechu). When pinna3, instead of bearing the leaflets 



