24 



PRACTICAL BOTANY, 



length, breadth, and depth (thickness). Accordingly, as 

 one or other, or none, of these dimensions predominates, 

 vegetable forms are said to be linear^ as leaf -stalks, include 

 ing cylindrical (terete), biangular (two-edged), triangular, 

 quadrangular, etc., forms ; plane or fiat, orbicular, elliptic, 

 or ovate, as leaves, etc. ; or solid (stereometrical), as fruits, 

 tubers, etc. 



66, Linear forms differ from one another in tJie shaj^e 

 of their cross-sections (see cuts below, I. a — A). 



'curved lines, f orbicular, : terete, or cylindrical — Fig.(a) 



and exhibit | semilunar, : semi-terete (b) 



different \ (lialf-terete) 



faces, elliptic or oval, : compressed (c) 



wliicli arc [ biangular, : two-edged (d) 



' vvitb straight sides : triangled. 

 .,, ( curved : triangular. 

 ^'^\ I inward (e) 



curve < curved : three-sided. 

 1^^^« [ outward (f) 

 with straight sides 

 .,-, f curved 



^^--1 cuiv^dn--^ 



[ ^^^^« Uutward (h) 



(Usually the terms triangular and three-sided, as well as quadrangular 

 &nd four-sided, are used indiscrimately.) 



All cross- 

 sections 



are 

 circum- 

 scribed 

 by 



straight or 



slightly 

 curved lines, 

 and exhibit 



tri- 

 angles 



square, 

 quadrangular. 



(g) 

 : four-sided. 



Cut I. 



67. Flat or plane forms are named from their whole 

 or ^partial outline. 



