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FOC | Family List | FOC Vol. 4 | Salicaceae

3. Salix Linnaeus, Sp. Pl. 2: 1015. 1753.

柳属 liu shu

Pleiariana 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 hainanica A. 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

1 Dwarf shrubs erect, ascending, procumbent, creeping, or cushion-shaped, usually less than 30(-50) cm tall.   (2)
+ Shrubs or trees erect, almost alwaysmore than 30 cm tall.   (8)
2 (1) Young leaves, young shoots, and flowers white woolly   31 Sect. Subviminales
+ Young leaves, young shoots, and flowers not white woolly.   (3)
3 (2) Bracts 2-colored, distal 1/2 dark brown or brown, proximal 1/2 lighter in color.   (4)
+ Bracts yellowish green or apically pinkish, brown on dried specimens.   (5)
4 (3) Petiole of some of leaves ca. 1/4 as long as leaf blade or longer   20 Sect. Diplodictyae
+ Petiole less than 1/4 as long as leaf blade   21 Sect. Myrtosalix
5 (3) Male flower with only an adaxial gland   7 Sect. Fulvopubescentes
+ Male flower with adaxial and abaxial glands.   (6)
6 (5) Plant erect or ascending   10 Sect. Floccosae
+ Plant creeping or cushion-shaped.   (7)
7 (6) At least some young leaves retuse at apex   16 Sect. Retusae
+ Young leaves not retuse at apex   11 Sect. Lindleyanae
8 (1) Stamens 3 or more.   (9)
+ Stamens 2(or 3) or connate into 1.   (13)
9 (8) Stamens 3(or 4)   5 Sect. Amygdalinae
+ Stamens (3 or)4-many.   (10)
10 (9) Bracts membranous; stamens 5(-8), adnate to base of bracts   2 Sect. Urbanianae
+ Bracts not membranous; stamens (3-)5-10, not adnate to bracts.   (11)
11 (10) Catkin less than 4 cm, densely flowered   4 Sect. Pentandrae
+ Catkin more than 4 cm, sparsely flowered at anthesis.   (12)
12 (11) Catkin rachis usually woolly or densely grayish white pubescent; petiole eglandular   1 Sect. Tetraspermae
+ Catkin rachis not woolly or grayish white pubescent; petiole usually glandular at apex   3 Wilsonia
13 (8) Male flower with adaxial and abaxial glands.   (14)
+ Male flower with only an adaxial gland.   (20)
14 (13) Catkin terminal on branchlets; plants 30-50 cm, rarely to 1 m tall   10 Sect. Floccosae
+ Catkin lateral on branchlets; plants more than 1 m tal.   (15)
15 (14) 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.   (16)
+ 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.   (17)
16 (15) Young leaves densely silky on both surfaces or only abaxially, tomentose or comose along midvein, rarely with sparse hairs; filaments pilose   13 Sect. Psilostigmatae
+ Young leaves glabrous on both surfaces; filaments glabrous (pilose at base in S. radinostachya)   8 Sect. Magnificae
17 (15) Young leaf blade mostly lanceolate; trees   6 Sect. Salix
+ Young leaf blade not lanceolate; shrubs, rarely small trees.   (18)
18 (17) Catkin ellipsoid or shortly cylindric, 4(-5) × as long as thick   12 Sect. Sclerophyllae
+ Catkin cylindric, more than 5 × as long as thick.   (19)
19 (18) 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 Sect. Denticulatae
+ Bracts pilose, with at least 1 surface pilose and ciliate; ovary pilose   14 Sect. Eriocladae
20 (13) Plants dwarf, usually 60(-100) cm tall.   (21)
+ Plants more than 1 m tall.   (24)
21 (20) Juvenile branchlets 1-1.5 mm thick; plants growing in marshes.   (22)
+ Juvenile branchlets more than 2 mm thick; plants not growing in marshes.   (23)
22 (21) Branchlets and young leaves glabrous or rarely pilose; bracts mostly uniformly colored except for pink apex   17 Sect. Myrtilloides
+ Branchlets and young leaves densely yellowish brown or white tomentose; bracts 2-colored   29 Sect. Incubaceae
23 (21) Young leaves conspicuously wrinkled adaxially; bracts obovate-orbicular, margin densely shortly ciliate   18 Sect. Chamaetia
+ Young leaves adaxially smooth; bracts long elliptic, with long, soft hairs (shaggy) adaxially   20 Sect. Diplodictyae
24 (20) Stamens 2, free, rarely connate at base within same catkin.   (25)
+ Stamens 2; filaments partly connate or completely connate into 1 stamen.   (41)
25 (24) Catkin pedunculate or subsessile, with leaflets at base.   (26)
+ Catkin sessile, without leaflets at base.   (36)
26 (25) Catkin peduncle more than 5 mm.   (27)
+ Catkin peduncle less than 5 mm or nearly absent.   (29)
27 (26) Catkin less than 5 × as long as thick   19 Sect. Glaucae
+ Catkin more than 5 × as long as thick.   (28)
28 (27) Young leaves abaxially silky downy or tomentose   14 Sect. Eriocladae
+ Young leaves abaxially glabrous or pubescent or, if ± silky, then most leaves not unfolded at anthesis   9 Sect. Denticulatae
29 (26) Filaments downy basally.   (30)
+ Filaments glabrous (except in a few species of   23 Sect. Arbuscella
30 (29) Young leaves pubescent, glabrescent   15 Sect. Heterochromae
+ Young leaves often russet or white silky or appressed downy.   (31)
31 (30) Young leaves russet or white silky; bracts glabrous or with long hairs   7 Sect. Fulvopubescentes
+ Young leaves appressed downy; bracts pilose only at base   9 Sect. Denticulatae
32 Young leaf blade dentate at margin.   (33)
+ Young leaf blade entire at margin.   (34)
33 (32) Young leaf blade lanceolate or oblanceolate, rarely elliptic or obovate at anthesis   23 Sect. Arbuscella
+ Young leaf blade narrowly obovate to suborbicular at anthesis   22 Sect. Hastatae
34 (32) Young leaves glabrous abaxially or tomentose only at base adaxially (except for cataphyll); bracts yellowish green or brown when dried   23 Sect. Arbuscella
+ Young leaves silky or tomentose abaxially; bracts dark colored toward apex.   (35)
35 (34) Filaments ca. 4 × as long as bracts; young leaf blade narrowly elliptic to elliptic   25 Sect. Lanatae
+ Filaments 2-3 × as long as bracts; young leaf blade undeveloped at anthesis or slightly oblanceolate to narrowly obovate   27 Sect. Argyraceae
36 (25) Catkin ellipsoid to shortly cylindric, rarely subglobose, 2-3.5 × as long as thick (sometimes cylindric in   28 Vimen
+ Catkin cylindric, more than 4 × as long as thick.   (40)
37 Leaf blade elliptic, obovate, or oblong-obovate.   (38)
+ Leaf blade linear or linear-lanceolate to oblong.   (39)
38 (37) Filaments ca. 2 × as long as bracts, glabrous   27 Sect. Argyraceae
+ Filaments nearly 3 × as long as bracts or longer, usually pilose at base   24 Vetrix
39 (37) Young leaf blade linear; branchlets yellowish, glabrous; plants growing on sand dunes   37 Sect. Flavidae
+ Young leaf blade linear-lanceolate to oblong; branchlets grayish green or reddish black, pilose or glabrous; plants not growing on sand dunes   24 Vetrix
40 (36) Bracts nearly black, apex acute   26 Sect. Daphnella
+ Bracts yellowish green to brown, apex obtuse or rounded   15 Sect. Heterochromae
41 (24) Leaf blade more than 6 × as long as wide or, if nearly 6 × as long as wide, then young branchlets gray downy or tomentose.   (42)
+ Leaf blade less than 6 × as long as wide.   (44)
42 (41) Branchlets and young leaves glabrous or slightly pilose, soon glabrescent   36 Helix
+ Branchlets and young leaves with appressed hairs or gray downy and tomentose.   (43)
43 (42) Anthers reddish purple; bracts black; young leaf blade linear-oblanceolate   35 Sect. Haoanae
+ Anthers yellow or yellowish red; bracts yellowish green or apex reddish; young leaf blade linear   34 Sect. Cheilophilae
44 (41) Catkin with leaflets at base or, if leaflets absent, then catkins opposite or subopposite.   (45)
+ Catkin without leaflets at base.   (47)
45 (44) Bracts yellowish green or brownish when dried, sometimes slightly pink distally; anthers yellow or reddish in distal part of catkin   33 Sect. Variegatae
+ Bracts brown to black; anthers reddish purple or, if yellow, then catkin less than 1 cm thick.   (46)
46 (45) Catkins opposite or, if alternate, then young leaf blade elliptic; anthers reddish purple; shrubs   32 Sect. Caesiae
+ Catkins alternate; young leaf blade lanceolate or oblanceolate, rarely long elliptic; anthers yellow or purple; trees   6 Sect. Salix
47 (44) Catkin long and slender, more than 3 cm, 4-5 mm thick; gland linear, more than 0.9 mm, apex usually incurved   30 Sect. Sieboldianae
+ Catkin short and thick, 1-3 cm, ca. 1 cm thick; gland ovate or linear, apex not incurved.   (48)
48 (47) Bracts yellowish green, brown when dried, glabrous or pubescent proximally   12 Sect. Sclerophyllae
+ Bracts nearly black, with long hairs.   (49)
49 (48) Anthers reddish purple   31 Sect. Subviminales
+ Anthers yellow   24 Vetrix

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