298 



BOTANT. 



3. Elliptical, wliicb is longer than broad, lias base and apex equal, 

 and sides rounded. 



4. Oblong, which is two to three times longer than broad, with 

 straight, parallel sides. Varieties of this are the linear, which is very 

 narrow and long : when this is rigid and sharp at the apex, it is the 

 needle-shaped leaf ; when small and thread-like, it is capillary. 



5. Oblique : any of the foregoing forms in which one side has be- 

 come broader than the other ; thus, obliquely ovate, obliquely Jieart- 

 shaped, etc. 



The Base and Apex> — In most leaves two extremities may be dis- 

 tinguished and described. There are three general forms, viz. , the 

 acute, obtuse, and notched. (Fig. 192.) 



The extremity is acute when the approaching sides form an acute 

 angle with each other. When the acute extremity is prolonged, it is 

 acuminate. When the apex ends in a bristle, it is cuspidate. 



The extremity is obtuse when blunt or rounded. When so blunt 

 as to seem as if cut off, it is truncate, as in what is known as the 

 wedge-shaped {cuneiform) leaf. In some cases a point or bristle 

 grows from the obtuse apex ; such are said to be mucronate. 



The extremity when indented is notched or emarginate : when 

 this is slight, it is refuse; when so deep from the apex as to appear 



Fig. 193.— Diagrams of the principal forms of base and apex. 



cleft, the leaf is bifid. A common form of emarginate apex is seen 

 in the obcordaie (i.e., inversely heart-shaped) leaf, while the emar- 

 ginate base is found in the cordate (i.e., heart-shaped) leaf. The 

 notch in the base of a leaf is also known as a sinus. 



Margin of the Blade. — When the growth of the leaf has been 

 uniform throughout, its margin is an even and continuous line, and 

 the blade is said to be entire. More commonly there are inequalities 

 in the growth ; when these are rounded and not great, the margin 

 may be wavy, or if somewhat more, sinuate, which readily passes 

 into the lobed form, with the projections {lobes) and the indentations 

 {sinuses) both rounded. (Fig. 193.) 



In some cases the projections alone are rounded, the sinuses being 

 narrow as if cut. When such projections are small, the blade is 



