S ALICACEAE, 57 
12. Leaves flat. P. balsamifera. 
Leaves wavy. P. laurifolia. 
13. Twigs sharply angled. P. Lindleyana. 
Twigs not angled. P. fortissima. 
14. Tree round-topped. 18. 
Tree oblong. x P. Eugenei. 
Tree pyramidal. P. migra: itahca: 
15. Leaves rather cuneate and attenuate. P. nigra. 
Leaves deltoid. 16. 
16. Buds glabrous. P. deltoides monilifera. 
Buds velvety. P. Sargentii. 
SALIX. Willow. Osier. 
Deciduous shrubs or trees with light brown wood with 
numerous minute scattered ducts and very fine medullary rays; 
round continuous pale pith; chiefly alternate sessile appressed 
oblong buds with a single exposed scale standing directly over 
the leaf-scar, the end-bud lacking; shallow U-shaped or trans- 
verse low leaf-scars with 3 bundle-traces; small if any stipule- 
scars; usually narrow rather small short-petioled leaves; dioeci- 
ous naked flowers in catkins; and small flask-shaped stalked 
capsules with numerous cottony seeds. 
1. Leaves green and glabrate on both sides, narrow. S. nigra. 
Leaves whitened beneath. 2. 
2. Leaves woolly beneath. 3. 
Leaves finally glabrous, or else silky beneath. 5. 
3. Leaves narrow, revolute. S. incana. 
Leaves broad, often crisped: catkins large. 4. 
4. Not weeping. S. caprea. 
Weeping. | S. caprea pendula. 
5. Leaves broad, veiny beneath. 6. 
Leaves narrow or elongated. 7. 
6. Young catkins large, (Pussy Willow). S. discolor. 
Catkins small and slender. S. cordata. 
7. Leaves glabrous, little whitened beneath. S. fragilis. 
Leaves silky or else distinctly white beneath. 8. 
