218 



BULLETIN 68. 



In cultivation in this country it is represented by no less than 

 three well marked botanical varieties, differing from the species 

 and from each other in the habit of growth, shape and color of 

 leaves and character of twigs. 



P. balsamifera variety intermedia (Loudon, Encyc. of Trees 

 and Shrubs, 830 (1842). P. laurifolia of American horticulturists, 

 not of botanists. P. Sibirica pyramidalis, of horticulturists). 



Fig. 4. A com- 

 paratively slow 

 growing tree of 

 close upright 

 habit, from 

 Northern Eur- 

 ope, where it is 

 used as a street 

 tree. The leaves 

 are very thick 

 and hard, finely 

 nat. serrate, oval in 

 outline, and 



prominently whitened beneath, and they are commonly rather small 

 for this group. Twigs hard and cylindrical. It is considered to 

 be a valuable tree for hot and dry interior climates ; and it also 

 has distinct merit for ornamental planting. It eventually becomes 

 a large tree. The Populus laurifolia and P. Sibirica pyramidalis 

 of American nurserymen are, so far as I can determine, only minor 

 variations of one varietal type. All these trees are amongst 

 the recent introductions of Russian poplars. 



P. balsamifera var. viminalis, (Loudon, Encyc. 830, t. 1510. 

 P. viminalis, L,odd. Cat. (1836). P. Lindleyana, Booth, Rev. 

 Hort. 1867, 380. P. salicifolia, P. crispa, P. Dudleyi, and P. 

 pyramidalis suaveolens of horticulturists. Also sometimes called 

 P. laurifolia]. Fig. 5. A tree of only moderate and rather slen- 

 der growth, with a partial weeping habit when old ; native to 

 northern Europe. It is at once distinguished from other forms of 

 Populus balsamifera by its sharply angled twigs (k, fig. i), and 

 broad-lanceolate willow-like leaves which are finely serrate and 

 often crinkled-margined. 



balsamifera variety intermedia, 

 size. 



