678 



CXCVII. BETULACE^L 



Birch. 



3 <J flowers with sqiiamifonn 

 perianth (inag.). 



Birch. 



Scale and aqiuuniila* 



of a <? catkin, outer 



face (mag.). 



Birch. 



Scale bearing 3 $ flowers 

 (mag.). 



Birch, (fietula alba.) 



J 1 and 9 catkins. 



Ainu*. 



Scale and squamulic 



bearing it 9 flowers, 



inner face. 



Jacquemont's Birch. 



Scale furnished with its 



3 fruits (mag.). 



A I nus. 



Scale bearing 3 <? 

 flowers (mag.). 



Alntu glutinoM. 



Scale furnished with 2 



Bquamulie, and bearing 



3 <? flowers (mag.). 



A In n.i. 

 Ripe 9 catkin. 



A I n n.i. 



Ripe 9 catkin cut 

 transversely (mag.). 



A In us. 

 Diagram of 2 9 flowers. 



Alnus. 

 Diagram of flower. 



Jacqnernont's Birch. 



Vertical section of fruit 



(mag.). 



coriaceous scales caducous when full grown (Betula} ; sometimes erect in a corymbose 

 raceme, with the scales at first fleshy, then woody and persistent (Alnus) ; scales 

 sessile, 3-lobed and flowered (Betula), or entire and each accompanied by 4 lateral 

 squainules, and 2-flowered (Alnus). PERIANTH 0. OVARY sessile, with twol-ovuled 

 cells, of which one is often empty ; stigmas 2, terminal, sessile, elongate, filiform ; 

 ovules pendulous from the septum a little below its top, anatropous. STROBILUS 

 formed by the enlarged scales. NUTS winged or annular, 1-celled and 1 -seeded. 

 SEED inverted ; testa membranous, thin. EMBRYO exalbuminous, straight ; cotyledons 

 plane, foliaceous in germination ; radicle superior. 



Betula. 



GENERA. 



* Alnus. 



Clethropsis. 



We shall indicate the affinities of Hctulacea with Cupulifera and Myricece under those families. 

 They approach Ulmacea: in the stamens being opposite to the calyx-lobes, in the 2-celled ovary and 



