22 THE MEMBERS OF PLANTS. 



branches run through the whole leaf-plate, which have 

 improperly been termed nerves, and sometimes veins, 

 but which I shall term leaf-ribs 1 , and their small 

 branches riblets 2 . 



The simplest form of leaf-ribs occurs in grasses and 

 other plants, the bases of whose leaves sheath or em- 

 brace the stems 3 ; and in some other leaves there 

 are, besides the main or mid rib 4 , in the middle of 

 the leaf two nearly as large at each side 5 , from which 

 botanists term such leaves three-nerved; and when 

 the large ribs are five, seven, or any other number* 

 they are named accordingly. In the tulip, no branches 

 are observable. 



Ribs of Leaves. a, grass leaf, one-ribbed; b, ivy leaf, three- 

 ribbed ; c, grape leaf, five -ribbed. 



By following out the branching from the mid-rib, 

 some clue may be obtained to the almost countless array 



(1) In Latin, Cosice folii. (2) In Latin, CostuJee. 



(3) In Latin, Folia amplexicaulia. (4) In Latin, Costa media. 



(5) In Latin, Costce laterales. 



