CUPULIFER/E 257 



Distrihution. — Europe, temperate and Arctic Asia ; N. America 

 (a variety). 



Betula puhescens Ehrh. 



A similar tree with narrower pointed leaves which are pubescent 

 and finally only downy at the midrib. Fruit broadly winged. 



Damp woods, peat-bogs and moors in the plains, sub-Alps and 

 Alps. April, May. 



Distribution. — Switzerland, Jura, Alps, Pyrenees ; Central and 

 Northern Europe, Caucasus, Northern Asia, Greenland. 



Alnus L. Alder. 



Stamens 4. Scales of female catkin persistent, woody. 

 Alnus viridis DC. Green Alder. (Plate XVIII.) 



A shrub sometimes attaining the height of a small tree in the 

 lower mountains. Leaves stalked, green, ovate-acute, doubly 

 serrate, glabrous. Flowers in monoecious catkins, male cylindrical, 

 drooping ; female oval, stalked, 2-5 in erect racemes, not \ inch 

 long, forming a woody cone ripening the second year. 



Mountains and clearings in the lower Alps, from 3000 to 6600 feet, 

 especially abundant on granite and schist. 



Distribution. — Central and Eastern Europe, Northern Asia and 

 America. 



Alnus incana Medik. 



A shrub or tree with silvery bark and oval-acute leaves doubly 

 serrate, glabrous above, downy and grey beneath. Fruit not 

 winged. 



Damp woods, borders of streams, etc., up to 5000 feet. March, 

 April. 



Distribution. — Alps, Jura ; Europe, temperate Asia, N. America. 

 Alnus glutinosa L. Common Alder. 



This weU-known tree has obtuse, almost orbicular leaves, which 

 are shortly petioled and sticky at first on the upper side. 



Damp woods, by water, etc., up to 4000 feet. February to April. 



Distribution. — Europe, temperate Asia, N. Africa. British. 



CORYLUS L. 



Fruit a woody, i-seeded nut, enclosed in the much enlarged 

 coriaceous involucre. Species 7. 



Corylus Avellana L. Hazel. 



A glandular, pubescent shrub, rarely a tree of 30 feet. Leaves 

 orbicular-cordate, doubly serrate cuspidate. Fruit a woody i-seeded 

 nut, enclosed in the greatly enlarged coriaceous involucre. Male 



