OF THE COMPO0ND LEAF. 



61 



hnmber and opposite. It is unequally pinnate wlieti the rachis bears 

 an odd terminal leaflet, and equally pinnate when there is no terminal 

 leaflet, and interruptedly pinnate when the leaflets are alternately large 

 and small (159, etc). 



288. The number of leaflets in the pinnate leap varies from 

 thirty pairs and upwards (as in some acacias), down to three, when the 

 leaf is said to be ternate or trifoliate ; or two, becoming hinate, or 

 finally even to one leaflet in the lemon. Such a leaf is theoretically 

 compound, on account of the leaflet (blade) being articulated to the 

 petiole. 



165 164 



Compound leavos. 162, Clematis. 163, Erigenia balbosa. 164, Acacia. 165, Honey-locust. 



289. A BipiNNATE LEAF (twicc pinnate) is formed wherf the rachis 

 bears pinnoe or secondary pinnate leaves, instead of leaflets, and tripin- 

 nate (thrice pinnate), when pinnae take the places of the leaflets of a 

 bipinnate leaf. When the division is still more complicated the leaf is 

 decompound. 



290. Transition leaves. Different degrees of division often exist in different 

 parts of the same lea^ illustrating tlie gradual transition of leaves from simple to 



169 166 168 167 



167, Lemon. 168, Jefferaonla. 169, Potentilla anserina. 166, P. tridentata. 



