OF THE COMPOUND LEAF. 



61 



number and opposite. It is unequally pinnate yrhen 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 leaf varies from 

 thii'ty pairs and upwards (as in some acacias), down to tlaee, when thp 

 loaf is said to be ternate or trifoliate; or two, becoming binate, ,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. 



162 165 164 



Compound leaves. 162, Clematis, 163, Erigenla bulbosa. 164, Acacia. 165, Iloney-lcicuflt. 



289. A BiPiNNATE LEAF (twicc pinnate) is formed when the rachis 

 bears ^'rawcE 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 



arts of the same lep,f, illustrating the gradaal transition of leaves from simple to 



169 166 168 lOT 



167, Lemon. 168, Jeflforsonio. 169, Potentlllo anserina. 166, P. tridentoto. 



