54 WILLOW FAMILY 



Key to the Species 



1. Leaves with much flattened petioles 



a. Petiole and lower leaf surface white or 



woolly; leaves lobed P. alba 



b. Petioles and mature leaves smooth 



(1) Leaves coarsely wavy-toothed, densely 



woolly at first /'. grand id entata 



(2) Leaves more finely crenate-toothed, 



smooth 



(a) Leaves round or ovate, short-pointed P. tremuloides 



(b) Leaves truncate at base, long-pointed 



x. Branches spreading; crown broad P. deltoides 



y. Branches erect ; crown long and nar- 

 row P. nigra italica 



2. Leaves with round or channeled petioles, 



a. Leaves 1-3 cm. wide, more or less lanceolate; 



petioles smooth P. an gusli folia 



b. Leaves 4-10 cm. wide, ovate; petioles hairy 



( 1 ) Leaves smooth on both sides, not heart- 



shaped at the base P. balsa mi f era 



(2) Leaves hairy below, heart-shaped at 



base P. b. candicans 



Populus alba Linne White Poplar, Silver Leaf 



Tall tree, 50-100 ft. high, 2-4 ft. diam. ; bark smooth, bright, gray 

 or yellow-green ; leaves ovate or broadly wedge-shaped, tip blunt or 

 rounded, base more or less truncate, densely white-woolly when young, 

 the upper surface becoming smooth and green at maturity, 4-6 cm. long, 

 3-4 cm. wide, petioles densely white-woolly, 3-4 cm. long; staminate 

 catkins 3-5 cm. long, fruiting catkins 5-6 cm. long, capsules small, 3 f 

 mm. long; alba, white, referring to leaves and bark. 



Cultivated and thence spreading spontaneously by means of root 

 sprouts; native of Eurasia. Flowering in March or April, the cottony 

 seeds flying in June. Our commonest variety is P. a. in v c a, often called 

 the "silver-leaf maple," with snowy lower leaf surface and larger lobes. 

 Propagated by cuttings and suckers. 



Wood white to yellowish, soft, weak, splitting with difficulty, weight 

 38 lbs.; used for boxes, flooring, interior finishing, rollers; of little value 



