CATKIN-BEARING TRIBE 265 



P. iremula (Aspen). Smaller than the last ; leaves smaller, 

 orbicular, toothed, not cottony beneath, borne on slender stems, 

 and therefore agitated by the least breath of air ; suckers from 

 the root. 



POPULDS (Poplar) 



P. nigra (Black Poplar). A tall tree of pyramidal growth. 

 Leaves rhomboid, serrated, not cottony beneath ; buds sticky ; 

 no suckers from the root. Not indigenous, but common by streams 

 and rivers. 



The Lombardy Poplar is not indigenous, having been introduced 

 from the East. 



Sub-order II. Myrice^e. Sweet-Gale Tribe 



3. Myrica (Sweet-Gale). Stamens and pistils on different plants ; 

 scales of the catkin concave ; stamens 4-8 ; stigmas 2 ; fruit drupe- 

 like, i-seeded. (Name, the Greek name of the Tamarisk.) The 

 only British species is M. Gale (Sweet-Gale). A low shrub, about 

 3 feet high, which has a sweet resinous smell when bruised. Leaves 

 ovate-lanceolate, toothed towards the upper end. . The catkins 

 appear before the leaves in the spring. Found in bogs in Scotland 

 and the north of England, and occasionally in the south. 



Sub-order III. Betuline^e. Birch Group 



4. Betula (Birch). Stamens and pistils in separate flowers 

 {monoecious) ; scales of the barren catkins in threes ; stamens 

 10-12 ; scales of the fertile catkin globed, ^-flowered ; stigmas 2 ; 

 fruit flattened, i-seeded, winged. (Name, the Latin name of the 

 tree.) There are two British species, viz. 



B. alba (Common, White, or Silver Birch). A very graceful 

 tree, with silvery-white bark, which peels from the trunk in a 

 curious manner. The branches are slender and somewhat pendu- 

 lous, and the leaves, borne on long stalks, are broadly ovate, 

 pointed, and serrate. A common forest tree. 



