Salix subg. Chamaetia

Shrubs, 0.005–6 m, clonal by layering or rhizomes, rarely root shoots, or not clonal. Stems erect, trailing, or decumbent; branches flexible at base, usually not glaucous (usually slightly or highly glossy). Buds usually arctica-type (alba-type in S. athabascensis), scale margins connate. Leaves: stipules usually absent or rudimentary, sometimes foliaceous; petiole shallowly or deeply grooved, convex, or flat adaxially, often not glandular, sometimes with 1 or 2 pairs of spherical glands distally; largest medial blade amphistomatous, hemiamphistomatous, or hypostomatous, (usually pinnately veined), narrowly to broadly elliptic, obovate, subcircular, circular, oblanceolate, narrowly oblong, oblong, or broadly obovate, 0.8–5.5 times as long as wide, angle of base and of apex usually less than or greater than 90o, (abaxial surface usually glaucous), surface hairs usually white, rarely ferruginous; juvenile blade (usually yellowish green), hairs usually white, rarely ferruginous. Catkins flowering as leaves emerge, usually from lateral buds (sometimes subterminal); staminate on flowering branchlet or sessile; pistillate on flowering branchlet, usually stout, globose, or subglobose, sometimes slender; floral bract brown, tawny, or bicolor, apex usually entire, sometimes toothed; pistillate bract usually persistent after flowering. Staminate flowers: abaxial nectary present or absent; stamens 2 (1 in S. uva-ursi); filaments distinct or connate, glabrous or hairy; anthers usually purple, or red turning yellow. Pistillate flowers: abaxial nectary absent or present; ovary usually not glaucous, hairy or glabrous, hairs flattened, ribbonlike, or cylindrical, beak abruptly or gradually tapering to styles or slightly bulged below styles; ovules 4–23 per ovary; styles usually connate; stigmas flat, abaxially non-papillate with rounded tip, or stigmas slenderly or broadly cylindrical, or 2 plump lobes.

Distribution

North America, Eurasia.

Discussion

Species ca. 133 (27 species in the flora).

Eight of the 14 sections recognized in this subgenus are found in the flora area.

Subgenus Chamaetia is difficult to separate from subg. Vetrix by morphological characters. It has diverged in habit, which is often dwarfed and rhizomatous; in leaf venation, which often is almost palmate with several veins that diverge from near the base of the blade; in buds, which often contain all the vegetative and reproductive structures that will be produced during the growing season; and less-needed structures such as cataphylls, and in some axillary buds, which are highly reduced. It is possible, as A. K. Skvortsov (1999) pointed out, that this reduction has gone so far that relationships are obscured. The primary characters that distinguish subg. Chamaetia are adaptations to arctic-alpine environments that involve simplification through reduction (Skvortsov). Molecular studies have not resolved any species usually placed in subg. Chamaetia from subg. Vetrix (E. Leskinen and C. Alström-Rapaport 1999; T. Azuma et al. 2000); two unpublished DNA studies also have not revealed a “Chametia” clade. A phenetic study (G. W. Argus 1997) revealed a distinct group separated at a level similar to other subgenera. The exception to this was sect. Glaucae, which sometimes clustered with subg. Chamaetia and other times with subg. Vetrix. This inconsistent clustering may be due to high polyploidy in sect. Glaucae, which may have evolved through hybridization with members of subg. Vetrix, perhaps sect. Hastatae. Although it is clear that subg. Chamaetia is more closely related to subg. Vetrix than to subg. Salix, it is highly probable that it is polyphyletic and does not deserve subgeneric rank. Until more information is available, it is taxonomically useful to treat it as a subgenus.

Selected References

None.

Lower Taxa

Salix sect. Chamaetia, Salix sect. Diplodictyae, Salix sect. Glaucae, Salix sect. Herbella, Salix sect. Myrtilloides, Salix sect. Myrtosalix, Salix sect. Ovalifoliae, Salix sect. Setchellianae

Key

1	Plants 0.08-6 m, (relatively low to tall) not dwarf	> 2
1	Plants 0.005-0.15 m, dwarf	> 11
2	Ovaries glabrous	> 3
2	Ovaries hairy (sometimes glabrescent in S. fuscescens)	> 6
3	Plants forming clones by root shoots; branchlets woolly; largest medial blades amphistomatous [2d2. Salix sect. Setchellianae].	Salix setchelliana
3	Plants not clonal or forming clones by layering; branchlets glabrous or velvety; largest medial blades hypostomatous	Salix sect. Myrtilloides
4	Branches red-brown, weakly glaucous; petioles 1-3.5 mm; stipes 0-0.4 mm; staminate abaxial nectaries present (Gaspe Peninsula, Quebec).	Salix chlorolepis
4	Branches yellow-brown or gray-brown, not glaucous; petioles 2-9 mm; stipes 0.4-3.2 mm; staminate abaxial nectaries present or absent	> 5
5	Stipules rudimentary; largest medial blades dull, glaucous or sparsely short-silky adaxially; proximal blade margins entire; staminate abaxial nectaries absent; stipes 2.1-3.2 mm; styles 0.1-0.2 mm; pistillate flowering branchlets 7-25 mm; plants clonal by layering.	Salix pedicellaris
5	Stipules foliaceous; largest medial blades slightly glossy, not glaucous adaxially; proximal blade margins serrulate; staminate abaxial nectaries present; stipes 0.4-1.2 mm; styles 0.6-0.8 mm; pistillate flowering branchlets 4-7 mm; plants not clonal.	Salix raupii
6	Juvenile blades glabrous; branchlets glabrous; largest medial blades glabrous abaxially, margins toothed proximally.	Salix fuscescens
6	Juvenile blades hairy; branchlets hairy or glabrescent; largest medial blades hairy abaxially, margins entire or toothed throughout	> 7
7	Juvenile and largest medial blades: hairs usually white, sometimes also ferruginous; branchlets pubescent.	Salix athabascensis
7	Juvenile and largest medial blades: hairs white; branchlets pilose, villous, tomentose, woolly, or long-silky to glabrescent	> 8
8	Largest medial blades: veins strongly impressed-reticulate adaxially, margins strongly revolute; branches dull; petioles with 2 dark spherical glands distally; catkins from subterminal buds.	Salix vestita
8	Largest medial blades: veins not strongly impressed-reticulate adaxially, margins slightly revolute or flat; branches slightly to highly glossy; petioles without glands distally; catkins from lateral buds	> 9
9	Petioles 1-27 mm, much longer than subtended buds; stipes 0.3-2.8 mm; largest medial blades narrowly elliptic, elliptic, oblanceolate, or obovate, apex acute, acuminate, convex, or rounded.	Salix glauca
9	Petioles 1.3-5 mm, often shorter than or barely exceeding subtended buds; stipes 0-0.6 mm; largest medial blades narrowly oblong, oblong, narrowly to broadly elliptic, narrowly oblanceolate or oblanceolate, obovate or ovate, apex acuminate, acute, rounded, or convex	> 10
10	Stipules absent or rudimentary on early leaves; ovules 2-10 per ovary; pistillate catkins stout to globose, densely flowered, 0.3-20 mm; floral bracts usually tawny; largest medial blades with flat margins.	Salix brachycarpa
10	Stipules foliaceous on early leaves; ovules 8-20 per ovary; pistillate catkins usually slender, sometimes stout or subglobose, moderately densely flowered, 16-69 mm; floral bracts tawny, brown, or black; largest medial blades with slightly revolute margins.	Salix niphoclada
11	Catkins from subterminal buds	> 12
11	Catkins from lateral buds	> 16
12	Largest medial blades glaucous abaxially; staminate abaxial nectaries present	> 13
12	Largest medial blades not glaucous abaxially; staminate abaxial nectaries present or absent	> 14
13	Plants 3-15 cm; stipules often rudimentary; largest medial blades amphistomatous or hemiamphistomatous, oblong to obovate or circular, usually broader, 1-1.5 times as long as wide, margins crenulate or entire; anthers 0.3-0.4 mm; filaments hairy throughout or on proximal 1/2; ovaries obclavate to pyriform; capsules 4.5-5 mm.	Salix reticulata
13	Plants 1-4 cm; stipules usually absent; largest medial blades hypostomatous, elliptic to broadly elliptic, usually narrower, 1.1-2.8 times as long as wide, margins entire; anthers 0.4-0.6 mm; filaments glabrous or hairy basally; ovaries obturbinate; capsules 3-4 mm.	Salix nivalis
14	Largest medial blades: margins crenulate, bases subcordate or cordate; styles 0.2-0.4 mm; pistillate abaxial nectaries present; floral bracts 0.5-1.5 mm.	Salix herbacea
14	Largest medial blades: margins entire, bases cuneate, rounded, or convex; styles 0.5-1.2 mm; pistillate abaxial nectaries absent; floral bracts 1.5-2.8 mm	> 15
15	Ovaries villous or pilose; leaves deciduous (in autumn); catkins more than 15-flowered; petioles 1.3-10 mm; branches red-brown.	Salix polaris
15	Ovaries glabrous or puberulent (hairs in patches, especially on beaks); leaves usually marcescent; catkins 2-15-flowered; petioles 0.4-5.5 mm; branches yellow-green, yellow-brown, or gray-brown.	Salix rotundifolia
16	Ovaries glabrous	> 17
16	Ovaries hairy	> 23
17	Largest medial blades not glaucous abaxially.	Salix nummularia
17	Largest medial blades glaucous abaxially	> 18
18	Largest medial blades highly glossy adaxially	> 19
18	Largest medial blades slightly glossy adaxially	> 21
19	Stamens usually 1; largest medial blades 4-23 mm; petioles 2-6.5 mm; ovules 4-9 per ovary; ovaries not glaucous; arctic-alpine northeastern North America and Greenland.	Salix uva-ursi
19	Stamens 2; largest medial blades 8.5-46 mm; petioles 1.1-20 mm; ovules 10-15 per ovary; ovaries glaucous or not; arctic northwestern North America	> 20
20	Branches trailing or erect, not or weakly glaucous; ovaries: beak gradually tapering to styles; styles 0.6-2 mm; largest medial blades amphistomatous or hemiamphistomatous; plants often rhizomatous.	Salix stolonifera
20	Branches trailing, not glaucous; ovaries: beak abruptly tapering to styles; styles 0.2-0.8 mm; largest medial blades hypostomatous; plants not rhizomatous.	Salix ovalifolia
21	Leaves and stipules marcescent; juvenile leaves yellow-green; stamens 1; staminate abaxial nectaries absent; largest medial blades: margins serrulate or crenulate.	Salix uva-ursi
21	Leaves and stipules deciduous; juvenile leaves reddish; stamens 2; staminate abaxial nectaries present or absent; largest medial blades: margins entire	> 22
22	Staminate catkins 5.5-14 mm; ovaries obnapiform, beak abruptly tapering to styles; Newfoundland.	Salix jejuna
22	Staminate catkins 21-53 mm; ovaries obclavate to pyriform, beak gradually tapering to styles or slightly bulged distally; Alaska, Northwest Territories.	Salix sphenophylla
23	Juvenile leaves reddish	> 24
23	Juvenile leaves yellowish green	> 26
24	Staminate catkins 21-53 mm, flowering branchlets 8-20 mm; ovaries: beak gradually tapering to or slightly bulged below styles; largest medial blades 19-52 mm.	Salix sphenophylla
24	Staminate catkins 4.8-15 mm, flowering branchlets 1-7 mm; ovaries: beak abruptly tapering to styles; largest medial blades 8-25 mm	> 25
25	Capsules 5.2-9.6 mm; largest medial blades hypostomatous, highly glossy adaxially; pistillate abaxial nectaries sometimes present; petioles 1.1-7(-16) mm; Alaska, Northwest Territories, Yukon.	Salix ovalifolia
25	Capsules 3-5 mm; largest medial blades amphistomatous or hemiamphistomatous, slightly glossy adaxially; pistillate abaxial nectaries absent; petioles 1.5-14 mm; Newfoundland.	Salix jejuna
26	Largest medial blades not glaucous abaxially	> 27
26	Largest medial blades glaucous abaxially	> 28
27	Largest medial blades deciduous, slightly glossy adaxially; petioles glabrous adaxially; floral bracts 1.5-2.5 mm; pistillate nectaries longer than stipes.	Salix polaris
27	Largest medial blades marcescent (becoming skeletonized), highly glossy adaxially; petioles hairy adaxially; floral bracts 1-1.3 mm; pistillate nectaries shorter than or equal to stipes.	Salix phlebophylla
28	Ovary hairs ribbonlike, usually crinkled (refractive); staminate abaxial nectaries absent; largest medial blades: margins closely and prominently serrulate or crenulate (sometimes entire in S. arctophila)	> 29
28	Ovary hairs flattened, not crinkled (white, not refractive); staminate abaxial nectaries present or absent; largest medial blades: margins entire	> 30
29	Largest medial blades: margins closely and prominently serrulate or spinulose-serrulate (teeth 7-14 per cm); stipes 0.2-0.4 mm; pistillate nectaries equal to or longer than stipes.	Salix chamissonis
29	Largest medial blades: margins inconspicuously crenulate or entire (teeth 1-8 per cm); stipes 0.8-1.4 mm; pistillate nectaries shorter than stipes.	Salix arctophila
30	Largest medial blades 9-26 × 3.8-7.5 mm, petioles 1.5-5 mm; plants forming rhizomatous mats; pistillate catkins 10-23 mm, 15-35(-43)-flowered; stipes 0-0.6 mm; staminate abaxial nectaries present.	Salix cascadensis
30	Largest medial blades 10-85 × 5.5-60 mm, petioles 2-35 mm; plants not forming rhizomatous mats (often trailing and rooting); pistillate catkins 20-145 mm, 18-80-flowered; stipes 0.2-1.6 mm; staminate abaxial nectaries present or absent	> 31
31	Branchlets usually villous or pilose, sometimes glabrous; floral bracts brown or black; stipules usually foliaceous; stipes 0.2-1.6 mm; styles 0.6-2.2 mm; plants 3-25 cm; arctic and northern cordillera.	Salix arctica
31	Branchlets usually glabrous, sometimes pilose to glabrescent; floral bracts tawny or light brown; stipules absent or rudimentary; stipes 0.2-0.8 mm; styles 0.4-1.6 mm; plants 2-10 cm; southern cordillera.	Salix petrophila