18 



GLOSSAJtr OF 



Division. 



Simple : when the blade is in one piece, however deeply it 

 may be cut. 



Compound : when the blade is in two or more distinct pieces, 

 which are then known as leaflets. 



A compound leaf is 



(a) Pinnate: when the leaflets are arranged on each 

 side of a central or mid rib ; and such a pinnate leaf will 

 be odd-pinnate if there is an odd leaflet at tlie end (Fig, 

 33) ; abrupt! y -pin nate if there is not a terminal leaflet 

 (Fig. 34) ; and pinnate u-ith a tendril if the mid-rib ends 

 in a tendril, as in Pea, etc. (Fig. 35). 



Again : the leaf is twice-pinnate if the primary divi- 

 sions are themselves pinnate (Fig. 36) ; thrice-pinnate if 

 the subdivision is carried through another stage ; and 

 decompound if still more divided. 



It is interruptedly -pinnate if, as in Tomato, there are 

 small leaflets interspersed among the larger ones (Fig. 37). 



(b) Palmate : if the leaflets are spread out from the 

 end of the petiole, like fingers (Fig. 38). 



A compound leaf is further described by mentioning 

 the number and form of the leaflets. (An example of the 

 complete descrijition of a compound leaf is given at the 

 beginning of the leaf-schedules later on). 



Venation. 



Straight- VEINED : when the veins run nearly parallel, either 

 from end to end of the leaf, as in grasses (Fig. 39), or 

 from a central rib to the margin, as in Calla (Fig. 40). 



Net-veined : when the veins run in all directions, forming a 

 net-work. Such a leaf is 



(a) pinnately-net-veincd : when there a distinct cen- 

 tral rib with the smaller veins^hranching from it on each 

 side (Fig. 41) ; and 



(b) palmately-net-veined : when there are several chief 

 ribs radiating from the end of the petiole (Fig. 42). 



Outline. 



1. Of leaves nearly alike at both ends. 

 Filiform : thread-like, as in Asparagus. 

 AcicuLAR : needle-shaped, as in Pine (Fiir. 43). 



