132 



PLAN DIAGRAMS 



[CH. 



diagrams of these with telling effect, introducing system 

 and order into these difficult cases. 



Fig. 34. ^4, plan diagrams of a <? , and B of a ? inflorescence of the 

 Birch ; C and D, of <? and ? inflorescences respectively of the Alder. In 

 each case the catkin- scale b has a small dichasium of three flowers (the 

 central one * absent in D, however) in its axil. The flowers of the 

 dichasium, of which the central is the oldest, are subtended by bracts a 

 and /3 and bracteoles a' and '. It is these bracts which join the catkin- 

 scales and give them their compound character (Ei). 



Fig. 35. Plan diagrams of Chestnut. A, of a <f lateral shoot with 

 distichous leaves; B, of a shoot with spirally arranged leaves and bearing 

 both <? and ? partial inflorescences ; C, of a cT partial inflorescence, show- 

 ing stamens and rudiment of pistil in the primary flower only. D, a ? 



