GENERAL MOEPHOLOGY OF THE PLANT 69 



1. Margins. — We have already stated that the condition of 

 the margins is dependent upon the extent to which the wings 

 of the epipodium and its branches are united. Thus if the 

 fusion of the wings of the several axes is complete and extends 

 to their apices, so that the margins are perfectly even, or ftee 

 from every kind of irregularity, the leaf is entire {figs. 92 and 

 116). But when the fusion is not quite complete, and the 



Fig. 120. 



Fig. 12 



Diagram of the margins of leaves, a. Bicrenate. 6. Biserrate. 

 c. Duplicato-dentate. 



margins are uneven, we have several modifications, which 

 are distinguished by characteristic terms. Thus, if the 

 margins present sharp indentations like the teeth of a saw, 

 and all point to the apex, the leaf is serrate {figs. 114 and 

 142), as in the common Dead-nettle ; if similar teeth point 



Fig. 121. 



Fig. 122. 



Fig. 121. Sinuated leaf of the Oak. Fig. 122. Spiny leaf of the Holly ine.c 



Aquifolium), with wavy margins. 



towards the base, the leaf is described as retroserrate ; ii 

 these teeth are themselves serrate, it is biserrate {figs. 120, b, 

 and 131), as in the Elm and Nettle-leaved Bell-flower ; when 

 the margins are minutely serrate, they are termed serrulate, as 

 in Barosma serratifolia. When the teeth are sharp, and pro- 

 ject almost or quite at right angles to the margin, the leaf is 

 dentate or toothed {Jigs. 110 and 137), as in the Melon, and the 



