58 



WOODY PLANTS 



row columnar crown; twigs glabrous, orange, changing to gray; 

 buds slender, glabrous. Introduced from Europe as an ornamen- 

 tal tree, spreading by sprouts; usually staminate. A striking tree 

 because of its formal columnar habit, often planted along avenues 

 (Fig. 33). 



6. P. balsamifera L. Balsam Poplar . Tacamahac. (P^ 

 tacamahacca Mill. ). A tree to 30 m. high, the trunk up to 2 m. 

 in diameter; bark on young stems greenish or reddish-brown, on 

 older trunks becoming gray or grayish-black, divided into scaly 

 or shaggy ridges; buds large, heavily coated with yellow balsam- 

 scented resin; branchlets lustrous, terete. River-banks and rich 

 soil, Labrador to Alaska, south to New York, Michigan, and 

 Colorado. 



7. P. gileadensis Rouleau. Balm of Gilead . Tree to 30 m. 

 with stout spreading branches; twigs brown, pubescent; buds large, 

 viscid. Horticultural in origin; only the pistillate tree is known, 

 spreading by sprouts and cuttings (Fig. 34). 



8. ^. eugenei Saint-Simon. Carolina Poplar. A tree to 30m. 

 high of pyramidal habit; twigs green, gray or buff; buds small, 

 viscid, tapering from base to apex. Horticultural in origin; only 

 the staminate tree is known, spreading from sprouts and cuttings; 

 formerly much planted as a street tree but now in disfavor because 

 the roots clog sewers (Fig. 35). 



9. P_. heterophylla L. Swamp Cottonwood . A tree up to 30 m. 

 high; bark furrowed, in narrow plates, somewhat scaly; branch- 

 lets whitish-tomentose, becoming glabrate and lustrous; buds 1- 

 1.5 cm. long, canescent-tomentose. Swamps and bottomlands, 

 mostly in the coastal plain, from Louisiana and Florida north to 

 New York, inland about the Great Lakes. 



MYRICA L. (Myricaceae) 



Aromatic shrubs or small trees, deciduous in cool climates. 

 Twigs rounded or angular, slender, resinous-dotted when young; 

 pith small, somewhat angled, continuous, green. Buds small, soli- 

 tary, sessile, sub-globose or ovoid, with 2 or 4 exposed scales; 

 end-bud absent. Leaf- scars alternate, half-elliptical or somewhat 

 3-sided, more or less raised; bundle-traces 3; stipule-scars (if 

 present) small. Fruit globose or ovoid, with a waxy coat or resi- 

 nous dots. 



a. Buds conical or oblong; 



fruits covered with resin-drops 1. M. gale 



