SURFACE. 



179 



By the outliiu' of tlic leaf, we refer to the general form of its margin, 

 wliether that he I'litire, or not. If not, then the j^eneral form of an 

 outHne is determined by connecting' the extreme points of its margin 

 with one another (Fig. 480, an ohovate onthne). It matters not, there- 

 fore, whether a leaf be entire, toothed, h)bed, or ])arted, or even if it be 

 entirely compoimd or decompound, its outline will l>e the same, pro- 

 vided a line connecting its extreme marginal points with one another 

 possess a given form. The forms of leaves on this basis may be divided 

 into three general classes — (a) those broadest at or about the middle, 

 (6) those broadest at some ])oint al)ove the middle, (c) those broadest 

 at some \nnnt below the middle. 



Vc?^ 



fz% 



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Fig. 4S4. A bullate upiicr 8urf;i( 



, A caiu'olla 



^ 



Of the first class, beginning with the narrowest, \\e have the Capillary 

 or I lair-like forms, the P^iliform or Thread-shaped (Fig. 491), the Acerose 

 or Needle-shaped (Fig. 492), as those of the pine, and the Linear or 

 Ribbon-shaped (Fig. 487), all of which are so elongated that they 

 present the appearance of being about of uniform width throughout. 



A leaf similar to but shorter than the linear, in proportion to its 

 breadth, without regard to the character of its apex or base, is Oblong 

 (Fig. 488). 



One of similar form, but Inning a length of not more than t^\i(•e or 

 thrice its breadth, and narrower than a circle, is ()\al (Figs. 489 and 

 490), a term which must not be confoniuied with Ovate. 



If an oblong or an oval leaf i)ossess a regularly rounded outline into 

 and through the ai)ical and basal portions, it is called Elliptical. \Ve 

 have, therefore, two forms of the elliptical leaf, denominated respectively 

 Oblong-Ellii)tical (Fig. 488) and ()val-Ellii)tical (Fig. 489). 



