LESSON 8.] THEIR FOKMS AS TO GENERAL OUTLINE. 57 



mon Pickerel- weed of our ponds, in the Banana (Fig.. 47), and many 

 similar plants of warm climates. 



145. Netted-veined leaves are also of two sorts, as is shown in 

 the examples already referred to. In one case the veins all rise 

 from a single rib (the midrib), as in Fig. 83. Such leaves are called 

 feather-veined or jdnnately-veined ; both terms meaning the same 

 thing, namely, ihat the veins are arranged on the sides of the rib 

 like the plume of a feather on each side of the shaft. 



146. In the other case (as in the Button wood. Fig. 50, Maple, 

 &c,), the veins branch off from three, five, seven, or nine ribs, which 

 spread from the top of the leaf-stalk, and run through the blade like 

 the toes of a web-footed bird. Hence these are said to be palmately 

 or dlgitately veined, or (since the ribs diverge tike rays from a 

 centre) radiate-veined. 



147. Since the general outline of leaves accords with the frame- 

 work or skeleton, it is plain that feather-veined leaves will incline to • 

 elongated shapes, or at least will be longer than broad ; while in 

 radiate-veined leaves more rounded ibrms are to be expected. A 

 glance at the following figures shows this. Whether we consider 

 the veins of the leaf to be adapted to the shape of the blade, or the 

 green pulp to be moulded to the framework, is not very material. 

 Either way, the outline of each leaf corresponds with the mode of 

 spreading, the extenf, and the relative 1< ngth of the veins. Thus, in 

 oblong or elliptical leaves of the feather-veined sort (Fig. 87, 88), 

 the principal veins are nearly equal in length ; while in ovate and 

 heart-shaped leaves (Fig. 89, 90), those below the middle are 

 longest; and in leaves which widen upwards (Fig. 91 — 94), the 

 veins above the middle are longer than the others. 



148. Let us pass on, without particular referpnce to the kind of 

 veining, to enumerate the principal ^^^—'^'^ 



149. F-ifms of leaves as to General Outline. It is necessary to give 



names to the principal shapes, and to define them rather precisely, 

 since they afford the easiest marks for distinguishing species. The 

 same terras are used for all other flattened parts as well, such as the 

 petals of the flowers ; so that they make up a great part of the 

 descriptive language of Botany. We do not mention the names of 

 common plants which exhibit these various shapes. It will be a good 

 exercise for young students to look them up and apply them. 



150. Beginning with the narrower and proceeding to the broadest 

 forms, a leaf is said to be 



S&F— 4 



