208 COMMON CANADIAN WILD PLANTS. 



one small scale to which is attached 4 short filaments ; 3 flowers 

 under each scale of the catkin. Fertile catkins stout, oblong, the 

 scales or bracts 5-lobed and with 2 or 3 flowers under each ; each 

 flower a naked ovary, becoming a winged nutlet in fruit. Bark 

 easily coming off in sheets. 



2. II nus. Catkins much as in Betula, but each fertile and sterile 

 flower has a distinct 3-5-parted calyx. Catkins solitary or clus- 

 tered at the ends of leafless branchlets or peduncles. Nutlets 

 wingless or nearly so. 



(These two genera are included in Cupulit'erse in Macoun's Catalogue.) 



1. BET'ULA, Tourn. BIRCH. 



1. B. lenta, L. (CHERRY- BIRCH. SWEET or BLACK BIRCH.) 

 Bark of the trunk dark brown, close, aromatic ; that of the 

 twigs bronze-coloured. Wood rose-coloured. Leaves ovate, 

 with somewhat heart-shaped base, doubly serrate, pointed, 

 short -petioled. Fruiting catkins sessile, thick, oblong- 

 cylindrical. Moist woods. 



2. B. lu'tea, Michx. (YELLOW or GRAY BIRCH.) Bark of 

 the trunk yellowish-gray, somewhat silvery, scaling off in 

 thin layers. Leaves hardly at all heart-shaped. Fruiting 

 catkins thicker and shorter than in No. 1. Moist woods. 



3. B. populifo'lia, Ait. (AMERICAN WHITE BIRCH. GRAY 

 BIRCH.) Leaves very tremulous on slender petioles, trian- 

 gular, very taper-pointed, nearly truncate at the base, 

 smooth and shining except when young. Bark of trunk 

 white, less separable than -in Canoe Birch. Poor soil, Atl. 

 Prov. 



4. B. papyra'eea, Ait. (B. papyri/era, Michx., in Ma- 

 coun's Catalogue.) (PAPER or CANOE BIRCH.) Bark of the 

 trunk white, easily separating in sheets. Leaves ovate, 

 taper-pointed, heart-shaped, long-petioled. Fruiting cat- 

 kins cylindrical, usually hanging on slender peduncles. 

 Woods. 



5. B. pu'mila, L. (Low BIRCH.) A shrub with brownish 

 bark, not glandular. Leaves ovate or roundish, pale 

 beneath ; veinlets on both surfaces finely reticulated. Cat- 

 kins mostly erect, on short peduncles. Bogs and low- 

 grounds , northward. 



