ALDER 



237 



catkin; 10, one of its scales bearing two female flowers, seen sejDarately 

 in 11 ; 12 14, fruiting scales seen from above, from below and from 

 the front ; 15, 16, the fruit whole and in section ; 17, ripe cone-like 

 fruiting catkins ; 18, one of the cone-like catkins after shedding its fruits ; 

 19, a twig; 20, section of branch, p. 237 (Wi). 



[The $ catkins in fruit are superficially cone-like. See 

 note, p. 202.] 



Alnus glutinosa, L. Alder (Figs. 74, 75). Tree with 

 dark bark and obovate leaves, in three series. Monoecious 

 anemophilous flowers in catkins, on firm, rough stalks. 



The (/ catkins at first stiff, then lax and pendent, 

 violet-brown, 5 6 up to 8 10 cm. long, smooth. Each 

 violet-brown to reddish scale of the ^ catkin subtends 

 a dichasial group of 3 flowers, each with 4 simple yellow 

 stamens opposite the segments of a 4-lobed perianth, and 



Fig. 75. Alder, Alnus glutinosa. A, shoot with s and catkins; B, 

 catkin-scale with three <? flowers and their bracts a ^ and bracteoles 

 a' /3' seen from above ; C, the same, without the flowers, seen from the 

 side ; D, plan-diagram of the same ; E, catkin-scale with its pair of ? flowers 

 aud their bracts and bracteoles seen from above ; F, the same with the 

 flowers removed ; G, the same fused to form the woody compound scale of 

 the ripe, fruiting catkin; H, plan-diagram of E. In all, h the cover-scale 

 (catkin-scale); a /3 the bracts; a' /3' the bracteoles; * the missing central 

 ? flower of the dichasium \n E ; axis of catkin (Ei). 



