104 



STRUCTURAL BOTANY. 



margin of the leaf or leaflet, with no reference to the general 

 form. If the leaf be even-edged, having the tissue completely 

 filled out, the appropriate term is, entire. Sometimes a vein runs 

 along such a margin as if a hem. 



309. But when the marginal tissue is deficient, the leaf be- 

 comes dentate, having sharp teeth pointing outward from the 

 centre ; serrate, with sharp teeth pointing forward, like the teetli 

 of a saw ; crenate, with rounded or blunt teeth. The terms 

 denticulate, serrulate, crenulate, denote finer indentations of the 

 several kinds ; doubly dentate, etc. , denote that the teeth aro 

 themselves toothed. 



387 



S81, Serrate leaf of Chestnut. 382, Doublv serrate leaf of Elm. 383, Dentate leaf of Arrow-wood 

 884, Crenate leaf of Catmint. 385, Repand leaf of Circaea. 386, Undulate leaf of Shingle Oak. 38/i 

 Lobed leaf of Chrysanthemum. 



310. The undulate, or wavy edge, is somewhat different from 

 the repand, which bends like the margin of an umbrella. If the 

 veins project, and are tipped with spines, the leaf becomes 

 spinous. Irregularly divided margins are said to be erose or 

 jagged, laciniate or torn, incised or cut. Often, instead of a 

 deficiency, there is a superabundance of marginal tissue, de- 

 denoted by the term crispate or crisped. 



311. Insertion. Several important terms descriptive of the 

 various modes of leaf-insertion must here be noticed. A sessile 

 leaf is said to be amplexicaul when its base lobes adhere to and 



