770 



THE PINE FAMILY. 



3. Black Poplar. Populus nigra, Linn. (Fig. 927.) 



(Eng. Bot. t. 1910.) 



A tall, quick-growing tree, readily 

 assuming a somewhat pyramidal form, 

 quite glabrous, with very glutinous buds. 

 Leaves broadly rhomboidal or nearly 

 triangular, tapering at the top, the lower 

 angles rounded, the edge crenated or 

 serrated, green on both sides. Catkins 

 loose, about 2 inches long, the scales 

 hairy only at the tips. Stamens more nu- 

 merous than in the Aspen or the white P., 

 and the lobes of the stigmas shorter and 

 broader. 



In moist places, the borders of streams, 

 etc., in central and southern Europe, 

 and the more temperate portions of Eus- 

 sian Asia. In northern Europe it has 

 been much planted, and is now common 

 in Scandinavia as well as in Britain, 

 but probably not truly indigenous even 

 in southern England. Fl. early spring. 



The well-known Lornbardy P. is believed to be a cultivated variety of 



the black P. of Eastern origin. 



Fig. 927. 



LXXIII. THE PINE FAMILY. CONIFERS. 



Trees or shrubs, mostly with resinous juice. Leaves stiff, and 

 in the European genera always entire, either subulate or linear, 

 or short or scale-like. Flowers monoecious or dioecious, in cylin- 

 drical or short catkins, with closely-packed scales, or the females 

 rarely solitary. Stamens inserted either on the axis of the catkin 

 under the scales, or the anther-cells sessile on the inside of the 

 scales themselves, which then form a part of the stamens. Ovules 

 and seeds naked, that is, without ovary, style, or pericarp, either 

 inserted under the catkin-scales or solitary and quite exposed. 



An extensive Order, spread over the whole globe, although within 

 the tropics chiefly confined to mountainous districts. In the northern 

 hemisphere they often form vast forests, and include the loftiest trees 



