Salix babylonica
Salix wolfii
weeping willow
Idaho willow, wolf willow, Wolf's willow
branches yellow-brown to red-brown;
branchlets sparsely to moderately densely tomentose, especially at nodes.
branches red-brown, violet, yellow-gray, or yellow-brown, pubescent or pilose to glabrescent;
branchlets yellowish, yellow-brown, red-brown, or yellow-green, sparsely or moderately densely pubescent, or densely long-silky, (inner membranaceous bud-scale layer free, separating from outer layer).
stipules absent or rudimentary on early ones;
petiole convex to flat or shallowly to deeply grooved adaxially, 7–9 mm, tomentose abaxially;
largest medial blade lanceolate, narrowly oblong, or narrowly elliptic, 90–160 × 5–20 mm, 5.5–10.5 times as long as wide, base cuneate, margins flat, spinulose-serrulate or serrulate, apex acuminate, caudate, or acute, surfaces glabrous or sparsely short-silky, hairs straight, dull adaxially;
proximal blade margins entire;
juvenile blade reddish or yellowish green.
stipules rudimentary or foliaceous on early ones, foliaceous on late ones, apex rounded, acuminate, or acute;
petiole convex to flat, or shallowly grooved adaxially, 3–12 mm, pubescent, long-silky, or villous adaxially;
largest medial blade narrowly oblong, narrowly elliptic, elliptic, or oblanceolate, 26–56 × 8–16.5 mm, 2.5–3.7–5.6 times as long as wide, base cuneate, convex, or rounded, margins flat, entire, apex acute, acuminate, or convex, abaxial surface not glaucous, pubescent, short-silky, or villous, hairs appressed or spreading, straight or wavy, adaxial dull, sparsely to densely silky or villous;
proximal blade margins entire;
juvenile blade yellowish green, densely short- or long-silky or villous abaxially, hairs white.
abaxial nectary 0.2–0.6 mm, adaxial nectary oblong or ovate, 0.4–0.7 mm, nectaries distinct or connate and cup-shaped;
filaments distinct, hairy on proximal 1/2 or basally;
anthers (sometimes reddish turning yellow), ellipsoid or globose.
(abaxial nectary 0–0.2 mm), adaxial nectary oblong, 0.4–1.1 mm, (nectaries distinct);
filaments distinct, glabrous;
anthers yellow, 0.3–0.5 mm.
adaxial nectary oblong, square, ovate, or obovate, 0.4–0.8 mm;
ovary ovoid or obturbinate, beak (sometimes pilose proximally), slightly bulged below or abruptly tapering to styles;
ovules 2–4 per ovary;
styles distinct or connate 1/2 their lengths, 0.2–0.3 mm;
stigmas flat, abaxially non-papillate with rounded tip, or 2 plump lobes (almost capitate), 0.2–0.3 mm.
adaxial nectary oblong, ovate, or flask-shaped, 0.4–1.1 mm, shorter to longer than stipe;
stipe 0.2–0.9 mm;
ovary pyriform, glabrous or hairy, beak gradually tapering to or slightly bulged below styles;
ovules 8–16 per ovary;
styles 0.3–1 mm;
stigmas flat, abaxially non-papillate with rounded or pointed tip, or slenderly or broadly cylindrical, 0.24–0.3–0.4 mm.
2–2.7 mm.
3–5 mm.
(flowering just before leaves emerge); staminate 13–35 mm, flowering branchlet 1–6 mm; pistillate densely flowered, stout or subglobose, 9–27 × 2.5–7 mm, flowering branchlet (0–)2–4 mm;
floral bract 1.1–1.8 mm, apex acute, rounded, or truncate, entire, abaxially sparsely hairy throughout or proximally, hairs wavy.
flowering as leaves emerge; staminate stout or subglobose, 9.5–16 × 6–12 mm, flowering branchlet 1–5.5 mm; pistillate moderately or very densely flowered, stout, subglobose or globose, 8.5–38 × 5–12 mm, flowering branchlet 1–11 mm;
floral bract brown, black, or bicolor, 0.8–2 mm, apex rounded or acute, abaxially hairy, hairs wavy, straight, or curly.
= 76.
Salix babylonica
Salix wolfii
Little is known about the origin of the strongly weeping cultivar of Salix babylonica. It was described by Linnaeus (1737[1738]) based on young garden specimens (W. J. Bean 1970–1988, vol. 4). It is thought to have originated in China, although it no longer occurs in the wild and its origin is uncertain. Selections are thought to have been transported to Europe along the trade route from China. In Tajikistan, there are three cultivated clones, one of which is staminate (A. K. Skvortsov 1999). Taxonomic treatments of S. babylonica are variable. Some botanists recognize a single species, including both pendulous and non-pendulous forms (Skvortsov), while others recognize four species: S. babylonica, with a weeping habit, S. capitata Y. L. Chou & Skvortsov, S. pseudolasiogyne H. Léveillé, and the commonly cultivated S. matsudana Koidzumi (Fang Z. F. et al. 1999), with an erect or spreading habit. Here, S. babylonica is treated in a narrow sense, including only weeping forms.
Salix babylonica is not cold tolerant and is not commonly grown in Europe (R. D. Meikle 1984) or in northern North America. In the flora area, cultivated trees with strongly pendulous branches and branchlets have been identified as S. babylonica (G. W. Argus 1985, 1986, 1993), but many are hybrids with S. alba (S. ×sepulcralis) or S. euxina (S. ×pendulina). Salix ×sepulcralis, especially nothovar. chrysocoma, with bright yellow branchlets, is the most commonly grown of these hybrids. All reported occurrences of S. babylonica need verification.
Hybrids:
Salix ×sepulcralis Simonkai: Weeping willow, S. alba × S. babylonica, is introduced from Europe and widely naturalized throughout the world. Synonyms include S. ×salamonii Carrière ex Henry and S. ×sepulcralis nothovar. chrysocoma (Dode) Meikle. It is characterized by: trees, to 12 m, stems pendulous; branches somewhat to highly brittle at base, yellowish, yellow-green, or yellow-brown; branchlets yellowish, yellow-green, or golden; stipules rudimentary or foliaceous on late leaves; petiole not glandular or with pairs or clusters of spherical glands distally or scattered throughout, short-silky adaxially; largest medial blade amphistomatous or hemiamphistomatous, narrowly elliptic to very narrowly so, margins finely serrulate or spinulose-serrulate, abaxial surface glaucous, adaxial glaucous, sparsely long-silky to glabrescent, hairs white or white and ferruginous, adaxial surface slightly glossy; catkins on distinct flowering branchlet 3–14 mm; staminate moderately densely flowered, slender, 23–53 × 3–9 mm; pistillate moderately densely to loosely flowered, slender to stout, 18–30 × 3–8 mm, flowering branchlet 3–14 mm; pistillate bracts persistent after flowering; staminate abaxial and adaxial nectaries distinct; stamens 2; anthers 0.5–0.8 mm; pistillate nectary longer than stipe; stipe 0–0.2 mm; ovaries gradually tapering to styles; ovules 4 per ovary; styles 0.15–2 mm; capsules 1–2 mm. In the flora area, it occurs in: British Columbia, New Brunswick, Nova Scotia, Ontario, Quebec; Alaska, Arizona, Arkansas, California, Connecticut, District of Columbia, Illinois, Iowa, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Missouri, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, Pennsylvania, Tennessee, Utah, Virginia, and West Virginia.
The most commonly cultivated, and sometimes escaped, weeping willow with golden or yellow-green branchlets is Salix ×sepulcralis nothovar. chrysocoma (Dode) Meikle. It probably originated as S. alba var. vitellina × S. babylonica (R. D. Meikle 1984). According to F. S. Santamour Jr. and A. J. McArdle (1988), S. ×sepulcralis cv. Salamonii has a broadly pyramidal crown and is only slightly pendulous. It is not clear just how this cultivar differs from S. ×pendulina. For a discussion of the taxonomy of these and other weeping willows see J. Chmela (1983).
Salix ×pendulina Wenderoth: Weeping willow, S. babylonica × S. euxina, is introduced from Europe and grown throughout the world. It is characterized by: trees, 2.5–12 m, stems pendulous; branches highly brittle at base, yellow-brown, gray-brown, or red-brown; branchlets yellowish to brownish; stipules foliaceous on late leaves; petioles glabrous, pilose, or velvety to glabrescent adaxially; largest medial blade amphistomatous or hypostomatous, very narrowly elliptic to lanceolate, or linear, margins serrulate, irregularly so, or spinulose-serrulate, abaxial surface glaucous, adaxial slightly glossy or dull; catkins on distinct flowering branchlet, 3–14 mm; staminate loosely flowered, stout, 16–34 × 7–11 mm; pistillate densely or moderately densely flowered, slender or stout, 20–36 × 3.5–11 mm; pistillate bract persistent after flowering; staminate abaxial and adaxial nectaries connate and shallowly cup-shaped; stamens 2; anthers 0.5–0.6 mm; pistillate nectary longer than stipe; stipe 0 mm; styles 0.2–0.6 mm; ovules 4–8 per ovary; capsules 1.8–3.5 mm. In the flora area, it occurs in: Ontario; California, Connecticut, District of Columbia, Georgia, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, Ohio, Oregon, Pennsylvania, Texas, Virginia, Washington, and West Virginia.
Reports of this hybrid in British Columbia and California are undocumented. Plants of Salix ×pendulina with prominent, caudate stipules are var. blanda (Andersson) Meikle; those with ovaries with patchy or streaky hairiness are var. elegantissima (K. Koch) Meikle.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
The two varieties of Salix wolfii are distinguished mainly by ovary hairiness; other characters in the key overlap. Ovaries of the typical var. wolfii are glabrous and those of var. idahoensis are hairy. In the latter variety, ovaries are sometimes hairy throughout, but most have hairs in streaks or in a patch at the base of the ovary and on the stipes. These plants usually do not set seed and may be infertile hybrids. Occasional occurrence of staminate flowers with abaxial nectaries suggests that this variety may be a hybrid with S. glauca or S. brachycarpa, although it could also be with S. eastwoodiae, as suggested by S. J. Brunsfeld and F. D. Johnson (1985). The presence of both abaxial and adaxial nectaries in staminate flowers of S. wolfii (staminate plants cannot be identified to variety) is an unusual character in subg. Vetrix; it rarely occurs in S. argyrocarpa, S. breweri, and S. orestera, but is common in S. wolfii. Both hairy ovaries and abaxial nectaries could have been acquired through hybridization and introgression, or polyploidy, with S. glauca or S. brachycarpa. Cytological study of S. wolfii may help answer this question.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Ovaries glabrous; pistillate adaxial nectaries 0.4-0.8 mm; stipes 0.2-0.9 mm. | var. wolfii |
1. Ovaries pubescent or tomentose (hairs in streaks or patches); pistillate adaxial nectaries 0.4-1.1 mm; stipes 0-0.4 mm | var. idahoensis |
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