BUDS AND LEAVES. 



19 



outstretched hand or the toes of a bird ; hence such leaves are said to be 

 palmately, digitately, or pedately veined. The leaves of the maple, 

 sycamore, and castor-oil plant (Fig. 27) will serve as illustrations. 



Between these two widely different forms of venation in exogenous 

 plants are other connecting ones, as when a leaf has both a mid-vein with 

 more or less strongly marked lateral branches and large diverging, palmate 

 branches also. 



Again, upon the venation of leaves depends, to a very great extent, their 

 marginal shape. In parallel-veined leaves the margin is commonly entire 

 that is, not notched or indented ; the common grasses, cat-tails, and 

 iris are familiar examples. In very many feather- veined leaves the margin 



PIG. 28. Marginal shapes of leaves. Beginning at the right, the first is serrate, second dentate, third be- 

 tween dentate and crenate, fourth creilate, fifth sinuate-toothed, sixth sinuate. Traced from nature. 



is also entire, as for example the magnolias, laurel, and flowering dogwood, 

 but more commonly they are variously notched or indented. Leaf mar- 

 gins so indented are, characterized in botanical descriptions by technical 

 terms which are, for the most part, self-explanatory ; as for example (Fig. 

 28), serrate, saw-toothed ; dentate, toothed, but with teeth less regular 

 than the preceding, and not pointing forward like them ; crenate, scal- 

 loped ; repand, undulate, or wavy, when the margin makes a wavy 

 line; sinuate, more strongly wavy or sinuous; incised, cut, jagged, 

 etc. Again, when the margin is deeply cut into a definite number of di- 

 visions, the leaf is said to be lobed, as three-lobed, five-lobed, or seven-lobed. 

 When cut more deeply than half way to the centre or base, the leaf is said 

 to be cleft, and hence the terms three-cleft, Jive-cleft, or trifid, quinquefid, 



