POPULUS. BETULA. 307 



scales notched at the end. Damp woods. T. IV. White Poplar. 

 Abele. 



2. P. canescens (Sm.); l.-buds downy not viscous, 1. roundish 

 angularly toothed cottony and white beneath, 1. of young shoots 

 cordate-ovate undivided,' stig. 2 wedgeshaped 3 4-lobed (pur- 

 ple). E. B. 1619. With suckers. L. not lobed, except occa- 

 sionally the youngest. Catkin-scales deeply cut at the end. 

 Damp woods. T. IV. Gray Poplar. E. 



3. P. tremula (L.) ; l.-buds glabrous slightly viscous, 1. nearly 

 round acute serrate glabrous on both sides, young 1. slightly 

 downy, stig. 2 bifid erect. E. B. 1909. A rather large tree, 

 with suckers. Fed. laterally compressed. Catkin-scales deeply 

 palmately cut. Woods. T. III. IV. Aspen. 



4. P. nigra (L.) ; I. triangular acuminate serrate glabrous, 

 " catkins lax cylindrical, stig. 2 roundish 2-lobed." E. B. 1910. 

 A large tree without suckers. L. remarkably triangular. Young 

 shoots glabrous. Catkin-scales palmately cut, glabrous. Damp 

 places, river-banks. T. III. Black Poplar. 



Tribe II. Myricea. 

 3. MYRICA Linn. Sweet Gale. 



1. M. Gale(L.); 1. lanceolate broader upwards serrate, st. 

 shrubby. E. B. 562. Height 34 feet. Bushy. Catkins ses- 

 sile, erect. Fr. with resinous glands. L. fragrant when bruised. 

 Bogs. Sh. V. 



Tribe III. Betulinea. 

 4. BETULA Linn. Birch. 



1. B. alba (L.) ; 1. rhomboid-triangular doubly serrate abruptly 

 acuminate, scales of the fern, catkins 3-lobed, lateral lobes falcate- 

 reflexed, fr. obovate-elliptical. E. B. 2198 (upper fig.). B. alba 

 Koch. B. odorata R. xii. 626. B. verrucosa Fries ! L. usually 

 glabrous often covered with resinous spots above, always having 

 a manifest tendency to. a rhomboidal form. Young shoots mostly 

 with resinous tubercles. Stip. ovate-lanceolate, acute, thrice as 

 long as broad, circinate ; sides not deflexed. Buds conical. Young 

 twigs often very long and pendulous. The catkin-scales distin- 

 guish this from the next ; the shape of the 1. also is different. 

 Rather common. T. IV. V. White Birch. 



2. B. glutinosa (Fries !) ; 1. rhomboid-ovate or cordate un- 

 equally serrate acute, scales of the fern, catkins 3-lobed, lateral 

 lobes ascending, fr. broadly obovate. E. B. 2198 (lower fig.). 

 B. alba R. xii. 623. B. pubescens Koch. L. usually glabrous, 



