Salix humboldtiana
Salix ballii
Humboldt's willow
ball's willow
stipules absent or rudimentary on early ones, foliaceous on late ones, apex acute or convex;
petiole shallowly to deeply grooved adaxially, 2.5–7.5 mm, pubescent;
largest medial blade elliptic to obovate, 23–63 × 10–35 mm, 1.4–2.8 times as long as wide, base convex or rounded, sometimes cordate or subcordate, margins flat, serrulate or sinuate, apex convex, rounded, acute, or acuminate, abaxial surface glaucous, glabrous, adaxial slightly glossy, glabrous or sparsely pubescent on midrib, (hairs white, sometimes also ferruginous);
proximal blade margins serrulate or crenulate;
juvenile blade sometimes reddish, glabrous, or midrib sparsely pubescent abaxially, hairs white, sometimes also ferruginous.
adaxial nectary oblong, square, or ovate, 0.3–1 mm;
filaments distinct, glabrous;
anthers yellow, 0.4–0.8 mm.
adaxial nectary square or oblong, 0.2–0.6 mm, shorter than stipe;
stipe 0.8–2 mm;
ovary pyriform, glabrous, beak gradually tapering to or slightly bulged below styles;
ovules 12–18 per ovary;
styles 0.4–1 mm;
stigmas flat, abaxially non-papillate with pointed tip, or broadly cylindrical, 0.2–0.3–0.36 mm.
3–6 mm.
humboldtiana Willdenow: Humboldt willow is not known to occur in the flora area.
is characterized by: trees, 4–25 m;
branches highly brittle at base, bud-scale margins distinct and overlapping adaxially;
stipules on late leaves rudimentary or foliaceous;
largest medial leaf blade usually linear, abaxial surface not glaucous, adaxial dull; pistillate bract deciduous after flowering;
stamens 3–7;
capsules with distinct, often raised, white veins.;
it occurs throughout much of Mexico to central Chile.
flowering as leaves emerge; staminate stout, 17–29.5 × 8–11 mm, flowering branchlet 3.5–12 mm; pistillate moderately densely flowered, slender, stout, or subglobose, 10–37.5(–45 in fruit) × 5–12 mm, flowering branchlet 2.5–16 mm;
floral bract brown or bicolor, 0.8–1.6 mm, apex rounded, convex or retuse, abaxially hairy throughout or proximally, hairs straight, curly, or wavy.
Salix humboldtiana
Salix ballii
Salix humboldtiana is closely related to S. nigra in its generally narrow leaf blades, which are not glaucous abaxially. The two differ in the following characters: S. humboldtiana has leaf blades linear to sometimes narrowly oblong (10–28.6 times as long as wide), ovaries usually ovoid to ellipsoid, ovary walls often stomatiferous and with raised, white veins, and capsule valves relatively thick, slightly recurved. S. nigra has leaf blades usually narrowly lanceolate (6–13 times as long as wide), ovaries pyriform to obclavate, ovary walls neither stomatiferous nor notably veined, and capsule valves relatively thin and strongly recurved. Both species occur in Chihuahua, Mexico.
The report by R. I. Lonard et al. (1991) that specimens identified as Salix nigra from the lower Rio Grande, Texas, resemble S. humboldtiana in having strongly veined capsules suggests that S. humboldtiana, or intergrades with that species, may occur in Texas. Attempts to locate a voucher specimen were unsuccessful; because strongly veined capsules are diagnostic, further field study is indicated.
An earlier name, Salix chilensis Molina, has been applied to this species; it does not seem to pertain to this taxon (C. K. Schneider 1918).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Occurrence of Salix ballii in Nunavut is on Charlton Island in James Bay.
Salix ballii differs from S. myrtillifolia in having leaves that are distinctly glaucous abaxially. It was described as S. myrtillifolia var. brachypoda by Fernald, who noted that among the characters that distinguish it from S. myrtillifolia only the presence of leaf glaucescence does not occur elsewhere in S. myrtillifolia. This character may be lost when dried over excessive heat. For example, the only specimen supporting the occurrence of S. myrtillifolia on the Gaspe Peninsula, Quebec, is a badly damaged, poorly dried collection that may have lost its glaucescence in drying. A single character difference such as this usually would not recommend a taxon for species rank, but in this case it may be justified inasmuch as S. ballii and S. myrtillifolia are allopatric. A specimen from Île Couture, Lac Mistassini Region, Quebec, may be an exception but confirmatory collections are needed.
Hybrids:
Salix ballii forms natural hybrids with S. glauca var. cordifolia (S. ×ungavensis Lepage). This sterile hybrid with aborted ovaries is known only from the type locality in northern Quebec. It generally resembles S. glauca var. cordifolia but its ovaries are glabrous except for hairy patches at the base and on the stipe. It is evidently a hybrid involving S. glauca var. cordifolia and a species with glabrous ovaries. E. Lepage (1962) was correct in suggesting that the latter was S. ballii (as S. myrtillifolia var. brachypoda). Both taxa grow together in the area; style and floral bract lengths fall within the range of S. ballii, except for a slight overlap with S. glauca var. cordifolia, and its serrulate to crenulate leaf margins are characteristic of S. ballii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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