GROUP IY. PHANEROGAMIA : DICOTYLEDONES : MONOCHLAMYDE.E. 581 



surface; in A. glutinosa, the black or common Alder, they are obovate or evea 

 emarginate, and green on both surfaces. In Ainu* viridis, the mountain Alder, 

 only the $ catkins are destitute of bud-scales in the winter: the fruit is winged. 

 Betula, the Birch. In both kinds of catkins the three flowers have only the 

 bracteoles a and /3. In the $ flowers the perianth is usually incomplete, and 

 there are only two stamens, the filaments of which are forked. In the ? 

 catkins, the two bracteoles cohere with the bract to form a three-lobed scale 

 which falls off together with the winged fruit. The $ catkins are borne ter- 

 minally on the shoots of the previous year, and are not covered with bud- scales 

 during the winter ; the 9 catkins are borne terminally on lateral dwarf-shoots 

 which have only a few leaves, and they are enclosed by bud- scales during the 

 winter ; as a consequence, flowering takes place after the unfolding of the 

 leaves. The shoots of successive yeais form sympodia, and the leaves are 

 arranged spirally. B. verrucosa has white glands on the leaves and young 

 shoots : B. pubescens has no glands, but the shoots are hairy ; it is a northern 

 form : B. fruticosa and B. nana are shrubs occurring in high latitudes : B. alba 

 is the common Birch. 



Order 2. CoRYLACEvE. Flowers 

 monoecious, in ^ and $ catkins. 

 The flowers have no perianth ; 

 that of the $ flower is rudi- 

 mentary. The inferior ovary is 

 bilocular ; one loculus is sterile, 

 the other contains two sus- 

 pended anatropous ovules : the 

 fruit is one- seeded and indehis- 

 cent (a nut). Two flowers are 

 borne in the axil of the bract of 

 the ? catkin, the median flower 

 being absent. The one-seeded 

 fruit is surrounded by a leafy 

 investment (cupule) formed by 

 the three bracteoles (a a i j3 l and 

 ft a, ft respectively, Fig. 382) of 

 median flower only is developed 

 deeply forked. 



Fio. 38 L Alnus glutinosa. A Branch 

 bearing catkins (in winter). B a group of 

 <J flowers (from above). C The same after 

 removal of flowers (lateral view). E Group 

 of ? flowers, seen from -within. F The 

 same after the removal of the flowers. G 

 a scale from the ? catkin : 6 bract ; a, /3, /3' 

 bracteoles. 



each side. In the <^ catkin the 

 : the filaments of the stamens are 



In Corylus, the Hazel, the ? catkin resembles a bud, since the external 

 sterile brcts have the same structure as the bud-scales (Fig. 385 B) ; the red 

 stigmata p'oject at the top ; the investment of the fruit is irregularly cut ; a 

 small piojection is formed on the fruit, the nut, by the remains of the epigynous 

 perianth. Each bract of the $ amentum bears two bracteoles a and /3, and a 

 flower consisting of four forked stamens (Figs. 385-6). Both kinds of amenta 

 are placed in the axils of the leaves of the previous year, and are not enclosed 



