CATKIN-BEARING TRIBE 265 



P. tremula (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. 



POPULUS (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. 



Suh-order II. Myrice.e. — Sweet-Gale Tribe 



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

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

 like, i-seeded. (Name, the Greek name ot 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. 



Siib-order III. Betuline^.. — Birch Group 



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

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

 10-13 ; scales of the fertile catkin 3-Iobed, ^-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. 



