152 ORGANOGRAPHY. 



1. Varieties of JReticuIated Venation. 



a. True netted. — In such a leaf, the midrib giA'es off branches 

 from its sides, which proceed at first towards the margins, and 

 then curve towards the apex, terminating finally within the 

 margin, Avith which they are connected by small veins, as in the 

 Dead-nettle (fig. 291), Lilac, &c. 



Fig. 291. Fig. 292. Fig. 293. 



Fig. 291. Leaf of the Dead- 

 nettle (Lamium). The 

 venation is the true netted, 

 and its margin is serrated. 



Fig. 293. Feather-veined 

 leaf of the Oak. Its 

 leaves are arranged in 

 a pinnatifid manner. 



Fig. 294. 



Fig. 292. Feather- veined leaf of the Spanish Chestnut. 



b. Feather-veined or pinnatehj-veined. — In these the midrib 

 gives off lateral veins which proceed at once to the margins, 

 and are connected by numerous branching vcinlcts, as in the 

 Beech, Chestnut (Jig. 292), Holly, Oak (fig. 293), &c. 



c. Ribbed. - This name is applied to 

 a leaf Avhich possesses three or more 

 ribs that run in a curved manner 

 from, at or near tlicir base to the 

 apex, towards which they converge; 

 such ribs being connected together 

 by brandling veins, as in Cinnamon 

 (fig. 294), Mchistoma, &c. If a ribbed 

 leaf has tliree ribs proceeding from 

 the base, it is said to bo three-ribbed or 

 tricostate ; if ^VQ, fire-ribbed or qninque- 

 costate ; if more tliaii five, mnUicoatate. 

 If the midrib of sucli a leaf gives off 

 on eacli side, a httlo above its base, 

 another rib, it is said to be triple- 



Ribbed leaf of Cin- 

 namon. 



