Genus: Salix

Salix - Willow

By Steven D. Glenn

Not peer reviewed

Last Modified 03/15/2013

Back to Salicaceae


Salix L., Sp. Pl. 2: 1015. 1753. Gen. Pl., ed. 5, 477. 1754. TYPE: Salix alba L. designated by Britton & Brown (1913) or Salix pentandra Hitchcock & Green (1929)

Vetrix Raf., Amer. Monthly Mag. & Crit. Rev. 1: 439. 1817. TYPE: Not designated.

Vimen Raf., Amer. Monthly Mag. & Crit. Rev. 1: 439. 1817. TYPE: Not designated.

Oisodix Raf., Amer. Monthly Mag. & Crit. Rev. 1: 439. 1817. TYPE: Not designated.

Usionis Raf., Alsogr. Amer. 14. 1838. TYPE: Not designated.

Ripselaxis Raf., Alsogr. Amer. 14. 1838. TYPE: Ripselaxis herbacea (L.) Raf. (=Salix herbacea L.).

Nectolis Raf., Alsogr. Amer. 15. 1838. TYPE: Not designated.

Amerina Raf., Alsogr. Amer. 15. 1838. TYPE: Not designated.

Diplusion Raf., Alsogr. Amer. 15. 1838. TYPE: Not designated.

Knafia Opiz, Seznam 56. 1852. TYPE: Unknown.

Lusekia Opiz, Seznam 61. 1852. TYPE: Unknown.

Key to the species of Salix

1. Leaves without apparent sharp teeth...2
1. Leaves with teeth...8

2. Leaves mostly glabrous beneath (excluding few hairs along main vein)...3
2. Leaves hairy throughout beneath...4

3. Small shrub, to 4 ft.; finely reticulate venation (3rd-level veins apparent); fruit glabrous; rare...Salix pedicellaris
3. Large shrub, over 4 ft.; without finely reticulate venation (3rd-level veins not readily visible); fruit hairy; common...Salix discolor

4. Leaves with white hairs beneath...Salix candida
4. Leaves with gray or red hairs beneath...5

5. Leaves with inrolled margins...Salix humilis
5. Leaves without inrolled margins...6

6. Leaves with sparse red or gray hairs beneath...Salix discolor
6. Leaves covered with gray hairs beneath...7

7. Leaves mostly 2.5 cm wide or less; scales subtending fruit pale...Salix bebbiana
7. Leaves (many) 2.6 cm wide or more; scales subtending fruit dark...Salix caprea

8. Leaves mostly glabrous beneath (excluding few hairs along main vein)...9
8. Leaves hairy beneath...19

9. Leaves opposite or subopposite...Salix purpurea
9. Leaves alternate...10

10. Petioles with glands (especially toward top)...11
10. Petioles lacking glands...13

11. Leaves with long-acuminate apices...Salix lucida
11. Leaves with acute-acuminate apices...12

12. Scales subtending fruit long-hairy throughout; native...Salix serissima
12. Scales subtending fruit long-hairy chiefly near the base; alien...Salix pentandra

13. Leaves glaucous beneath...14
13. Leaves green beneath...18

14. Leaves with teeth widely spaced, 3 or fewer per cm...Salix discolor
14. Leaves with teeth closely spaced, 4 or more per cm...15

15. Leaves mostly 1.9 cm wide or more...16
15. Leaves mostly 1.8 cm wide or less...17

16. Stipules large, persistent; small or no glands on teeth; scales subtending fruit dark...Salix eriocephala
16. Stipules small or lacking; prominent glands on teeth; scales subtending fruit pale...Salix fragilis

17. Leaves with long-acuminate and often falcate apices; twigs/branches pendulous; fruit glabrous...Salix babylonica
17. Leaves with acute-acuminate apices; twigs not pendulous; fruit hairy...Salix petiolaris

18. Leaves with teeth widely spaced, 5 or fewer per cm; usually lacking stipules; fruit hairy...Salix exigua
18. Leaves with teeth closely spaced, 6 or more per cm; usually with prominent stipules; fruit glabrous...Salix nigra

19. Leaves mostly 1.8 cm wide or less...20
19. Leaves mostly 1.9 cm wide or more...21

20. Current year’s twigs yellow-tan; fruit glabrous...Salix alba
20. Current year’s twigs brown-gray; fruit hairy...Salix sericea

21. Leaves with sparse red or gray hairs beneath...Salix discolor
21. Leaves covered with gray hairs beneath...22

22. Leaves mostly 2.5 cm wide or less; scales subtending fruit pale...Salix bebbiana
22. Leaves (many) 2.6 cm wide or more; scales subtending fruit dark...Salix caprea

List of Salix Species

Other Links

Interactive Salix key:

References to Salix

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