WILLOW FAMILY 73 



flowers appearing before the leaves in red-brown or yellowish hanging cat- 

 kins with fringed scales; leaves alternate simple, usually broad; trees. 



1. Leaves with much flattened petioles 



a. Leaves rounded, short-pointed, entire or finely 



toothed P. tremuloides : 



aspen. 



b. Leaves broadly triangular, long-pointed, 



coarsely toothed P. deltoides : 



cottonwood 



2. Leaves with round or roundish petioles 



a. Leaves broadly ovate or rounded, whitish be- 



neath P. balsamifera 



b. Leaves lanceolate to lance-ovate, green be- 



neath 



(1) Leaves blunt or acute, 5-15 cm. long, 1-4 



cm. wide P. angustifolia 



(2) Leaves long-pointed, 5-10 cm. long, 2-5 



cm. wide P. acumindta 



SALIX Linne 1753 WILLOW 



(L. salix, willow, or sallow, the old English name of the willow) 



Plates 12-13. 



Sepals and petals none, stamens 1-10, usually 2, ovary 1 -celled, stigmas 

 2, fruit 2-valved, smooth or hairy; flowers appearing before the leaves in 

 gray, greenish or yellow catkins, with entire usually hairy scales; leaves 

 alternate, simple, mostly narrow ; ours mostly shrubs. 



1. Stems low and creeping, mat-like, 1-4 in. high 5. reticuldta 



2. Stems taller, 1-50 feet high 



a. Leaves smooth or nearly so on both sides when 

 mature 



(1) Leaves linear, linear-oblong or lance- 



linear 5. fluvidtilis 



(2) Leaves broader, lanceolate to obovate 

 (a) Shrubs 



x. Young twigs with a bluish bloom 



y. Young twigs without a bluish bloom; 



leaves oblong lanceolate S. irrordta 



(x) Leaves entire, or mostly so 



m. Leaves lanceolate to lance-ovate 5. chlorophylla 

 n. Leaves obovoid S. Nuttdllii 



