24 LEAVES, FLOWERS, AND FRUIT 



Veining of Blades of Leaves. — Another of the differ- 

 ences in the blades of leaves necessary to know is that of 

 the veining (see Plates I— IV, Figs. A-X). Nearly all 

 blades will be found to have a conspicuous central vein 

 called the midrib extending the length of the blade. 

 Frequently there are two or more side veins of almost 

 equal strength extending from the base of the blade. If 

 these are more conspicuous than others and extend out- 

 ward toward the sides, the blades are said to be radiate- 

 veined; but if they more or less follow the direction of the 

 midrib, the blades are said to be 3-ribbed, 5-ribbed, or 

 7-ribbed as the case may be. A more common veining is 

 when the only rib extending from the base is the midrib 

 and the veins next in size extend from this in a regular 

 manner outward from base to tip ; this gives what is 

 called feather-veining. A peculiar variety of feather- 

 veining is shown in birch and elm' leaves, where the veins 

 along the sides of the midrib are distinctly marked and 

 extend nearly parallel with each other to the margin of 

 the blade ; this is called straight-veined. 



Between all these ribs and veins there is, in almost all 

 bushes, a network of fine veins which gives the name net- 

 veined to the blades. In the United States there are 

 many leaves so thick and fleshy that this network does 

 not show, and the blades are well described as obscurely 

 veined. In such plants as wheat, corn, and the palms the 

 veining does not form a network and the leaves are said 

 to be parallel-veined: 



Forms of Blades. — (See Plates I-IV, Figs. A-X, also 

 other fig,ures in book.) In the description of blade 

 forms in this book only the commonest of English words 

 are used and most readers will understand them without 

 explanation and illustration; but for those who need a 

 review of form words and their explanation a few para- 

 graphs are given. 



Broad blades more than half as wide as long will, if 

 widest at about the middle, be called oval; if widest near 



