FORM OR FIGURE. 



55 



of individual forms of outline we shall select only the most remarkable, leaving 

 others for explanation in the glossary, 



264. The most obvious aeransement is that which is founded upon the modes 

 of veining ; but it should be premised that different forms of venation often give rise 

 to the same outline. Were we required to characterize our idea of the abstract, 

 typical leaf-form, we should sketch an oval outline of surface, with equal aides and 

 nnequal ends. The nearest approach to this we find, among the 



Diagrams of pinnate-veined leaf-forms. 



119, orbicular, 



120, oval, 



121, elliptical, 



122, oblong, 



123, cuneiform. 



124, spatbulate, 



125, oblanceolate, 



126, obovate, 



127, deltoid, 



128, lanceolate, 



129, ovate. 



265. Feather-veined LEAVES. Of these, the following 

 forms depend upon the length of the veinlets in relation 

 to each other and to the midvein. When the lower veinlets are longer 

 than the others, the form of the blade will be (1) ovate, with the out- 

 line of an egg, the broad end at the base ; (2) lanceolate, or lance- 

 shaped, narrower than ovate, tapering gradually upwards ; (3) deltoid or 

 triangular shaped, like the Greek letter A. 



a. Ip the middle veinlets exceed the others in length, the leaf will 

 be (4) orbicular, roundish or quite circular ; (5) elliptical, with the 

 outline of an ellipse, nearly twice longer than broad; (6) oval, broadly 

 elliptical ; (V) oblong, narrowly elliptical. 



266. When the veinlets are more largely developed in the 

 upper region of the leaf its form becomes (8) obovate, inversely 

 ovate, the narrow end at base ; (9) oblanceolate, that is, lanceolate with 

 the narrow end at base; (10) spatulate, like a spatula, with a narrow 

 base and a broader, rounded apex; (11) cuneate or cuneiform, shaped 

 like a wedge with the point backwards. 



26*7. Again, if the lowest pair of veinlets are lengthened and 

 MORE OR LESS EEcuBVED, the leaf will be variously modified in respect 

 to its base, becoming (12) cordate, or heart-shaped, an ovate outline 

 with a sinus or reentering angle at base; (13) auriculate, with ear- 

 shaped lobes at base; .(14) sagittate, arrow-shaped, with the- lobes 

 pointed, and directed backwards; (15) Aa«ta<e,halbert-shaped, the lobes 

 directed outwards. 



