Flora of China 4: 162–274. 1999. 3. SALIX Linnaeus, Sp. Pl. 2: 1015. 1753. 柳属 liu shu Pleiarina N. Chao & G. T. Gong. Trees or shrubs deciduous, rarely evergreen (if shrubs, then erect, ascending procumbent, creeping, or cushion- shaped); pith terete. Branches terete. Terminal bud usually absent; buds with single scale. Leaves alternate, rarely subopposite or opposite; stipules small, free, deciduous or persistent, developed mainly on vigorous branchlets; petiole short; leaf blade variously shaped, often long and narrow. Flowering precocious, coetaneous, or serotinous; catkins upright or spreading, rarely pendulous; bracts entire, persistent or caducous. Flowers entomophilous or anemophilous, each with 1 or 2 glands: 1 abaxial (dorsal) or absent and 1 adaxial (ventral), i.e., abaxial gland between bract and stipe, adaxial gland between stipe and rachis. Male flower: stamens 2–many; filaments free or partly to completely connate, usually exceeding bracts; anthers 2-loculed (rarely 4-loculed if filaments connate), opening lengthwise. Female flower: ovary 2-loculed, sessile or stipitate; style 1, short, slender, or absent, entire or 2- cleft; stigmas 1 or 2, lobed or entire. Capsule 2-valved. Seeds mostly green or gray-green, small, surrounded by fine hairs. About 520 species: cold and temperate regions of N hemisphere, a few in S hemisphere; 275 species (189 endemic, at least one introduced) in China. A. K. Skvortsov indicates that sections Caesiae, Flavidae, Haoanae, and Helix are in many ways interrelated and might, therefore, be united. Salix hainanicaA. K. Skvortsov (Harvard Papers in Botany 3: 107. 1998), was published just after this account was finalized, and it should be referred to sect. Tetraspermae. The genus Pleiarina,to which several taxa of Salix were transferred by N. Chao and G. T. Gong (J. Sichuan Forest. Sci. Tech. 17(2): 1–8. 1996), is here treated as a synonym of Salix. Key to sections based on male plants 1a. Dwarf shrubs erect, ascending, procumbent, creeping, or cushion-shaped, usually less than 30(–50) cm tall. 2a. Young leaves, young shoots, and flowers white woolly ............................................................ 31. Subviminales 2b. Young leaves, young shoots, and flowers not white woolly. 3a. Bracts 2-colored, distal 1/2 dark brown or brown, proximal 1/2 lighter in color. 4a. Petiole of some of leaves ca. 1/4 as long as leaf blade or longer .......................................... 20. Diplodictyae 4b. Petiole less than 1/4 as long as leaf blade ................................................................................. 21. Myrtosalix 3a. Bracts yellowish green or apically pinkish, brown on dried specimens. 5a. Male flower with only an adaxial gland ......................................................................... 7. Fulvopubescentes 5b. Male flower with adaxial and abaxial glands. 6a. Plant erect or ascending ......................................................................................................... 10. Floccosae 6b. Plant creeping or cushion-shaped. 7a. At least some young leaves retuse at apex .............................................................................. 16. Retusae 7b. Young leaves not retuse at apex ...................................................................................... 11. Lindleyanae 1b. Shrubs or trees erect, almost alwaysmore than 30 cm tall. 8a. Stamens 3 or more. 9a. Stamens 3(or 4) ......................................................................................................................... 5. Amygdalinae 9b. Stamens (3 or)4–many. 10a. Bracts membranous; stamens 5(–8), adnate to base of bracts ................................................ 2. Urbanianae 10b. Bracts not membranous; stamens (3–)5–10, not adnate to bracts. 11a. Catkin less than 4 cm, densely flowered ............................................................................. 4. Pentandrae 11b. Catkin more than 4 cm, sparsely flowered at anthesis. 12a. Catkin rachis usually woolly or densely grayish white pubescent; petiole eglandular .. 1. Tetraspermae 12b. Catkin rachis not woolly or grayish white pubescent; petiole usually glandular at apex ...... 3. Wilsonia 8b. Stamens 2(or 3) or connate into 1. 13a. Male flower with adaxial and abaxial glands. 14a. Catkin terminal on branchlets; plants 30–50 cm, rarely to 1 m tall ........................................ 10. Floccosae 14b. Catkin lateral on branchlets; plants more than 1 m tall 15a. Catkin stout, pedunculate or not, more than 8 mm thick or, if catkin only ca. 5 mm thick, then inflorescence more than 5 cm or nearly all filaments pubescent; young leaf blade already large at anthesis, usually 3–4 cm. Flora of China 4: 162–274. 1999. 16a. Young leaves densely silky on both surfaces or only abaxially, tomentose or comose along midvein, rarely with sparse hairs; filaments pilose ................................................... 13. Psilostigmatae 16b. Young leaves glabrous on both surfaces; filaments glabrous (pilose at base in S. radinostachya) ................................................................................................................... 8. Magnificae 15b. Catkin slender, less than 8 mm thick, rarely more than 1 cm thick and then mostly ellipsoid or shortly cylindric; young leaf blade less than 3 cm at anthesis. 17a. Young leaf blade mostly lanceolate; trees ................................................................................... 6. Salix 17b. Young leaf blade not lanceolate; shrubs, rarely small trees. 18a. Catkin ellipsoid or shortly cylindric, 4(–5) × as long as thick .................................. 12. Sclerophyllae 18b. Catkin cylindric, more than 5 × as long as thick. 19a. Bracts usually glabrous or only ciliate or, if pilose on 1 or both surfaces, then gland ca. 1/2 as long as bracts or longer; ovary glabrous ................................................................... 9. Denticulatae 19b. Bracts pilose, with at least 1 surface pilose and ciliate; ovary pilose ........................ 14. Eriocladae 13b. Male flower with only an adaxial gland. 20a. Plants dwarf, usually 60(–100) cm tall. 21a. Juvenile branchlets 1–1.5 mm thick; plants growing in marshes. 22a. Branchlets and young leaves glabrous or rarely pilose; bracts mostly uniformly colored except for pink apex ....................................................................................................................... 17. Myrtilloides 22b. Branchlets and young leaves densely yellowish brown or white tomentose; bracts 2-colored 29. Incubaceae 21b. Juvenile branchlets more than 2 mm thick; plants not growing in marshes. 23a. Young leaves conspicuously wrinkled adaxially; bracts obovate-orbicular, margin densely shortly ciliate .......................................................................................................................................... 18. Chamaetia 23b. Young leaves adaxially smooth; bracts long elliptic, with long, soft hairs (shaggy) adaxially 20. Diplodictyae 20b. Plants more than 1 m tall. 24a. Stamens 2, free, rarely connate at base within same catkin. 25a. Catkin pedunculate or subsessile, with leaflets at base. 26a. Catkin peduncle more than 5 mm. 27a. Catkin less than 5 × as long as thick .............................................................................. 19. Glaucae 27b. Catkin more than 5 × as long as thick. 28a. Young leaves abaxially silky downy or tomentose ................................................. 14. Eriocladae 28b. Young leaves abaxially glabrous or pubescent or, if ± silky, then most leaves not unfolded at anthesis ............................................................................................... 9. Denticulatae 26b. Catkin peduncle less than 5 mm or nearly absent. 29a. Filaments downy basally. 30a. Young leaves pubescent, glabrescent .............................................................. 15. Heterochromae 30b. Young leaves often russet or white silky or appressed downy. 31a. Young leaves russet or white silky; bracts glabrous or with long hairs ...... 7. Fulvopubescentes 31b. Young leaves appressed downy; bracts pilose only at base ................................ 9. Denticulatae 29b. Filaments glabrous (except in a few species of 23. Arbuscella). 32a. Young leaf blade dentate at margin. 33a. Young leaf blade lanceolate or oblanceolate, rarely elliptic or obovate at anthesis 23. Arbuscella 33b. Young leaf blade narrowly obovate to suborbicular at anthesis .............................. 22. Hastatae 32b. Young leaf blade entire at margin. 34a. Young leaves glabrous abaxially or tomentose only at base adaxially (except for cataphyll); bracts yellowish green or brown when dried ...................................... 23. Arbuscella 34b. Young leaves silky or tomentose abaxially; bracts dark colored toward apex. 35a. Filaments ca. 4 × as long as bracts; young leaf blade narrowly elliptic to elliptic . 25. Lanatae 35b. Filaments 2–3 × as long as bracts; young leaf blade undeveloped at anthesis or slightly oblanceolate to narrowly obovate ........................................................ 27. Argyraceae 25b. Catkin sessile, without leaflets at base. 36a. Catkin ellipsoid to shortly cylindric, rarely subglobose, 2–3.5 × as long as thick (sometimes cylindric in 28. Vimen). 37a. Leaf blade elliptic, obovate, or oblong-obovate. Flora of China 4: 162–274. 1999. 38a. Filaments ca. 2 × as long as bracts, glabrous ......................................................... 27. Argyraceae 38b.