Salix humboldtiana
Salix serissima
Humboldt's willow
autumn willow
stipules absent or rudimentary;
petiole shallowly to deeply grooved adaxially, 3–13 mm, with pairs of spherical glands distally or throughout, glabrous adaxially;
largest medial blade hypostomatous or hemiamphistomatous, narrowly oblong, very narrowly elliptic, elliptic, lanceolate, or narrowly ovate, 43–110 × 9–33 mm, 2.4–6 times as long as wide, base convex or cuneate, margins flat, serrulate, apex acuminate, caudate, or acute, abaxial surface usually not glaucous, sometimes thinly so (appearing pale green), slightly glossy, glabrous, adaxial highly glossy, glabrous;
proximal blade margins serrulate or entire;
juvenile blade reddish or yellowish green, glabrous abaxially.
abaxial nectary 0.5–1.1 mm, adaxial nectary oblong or ovate, 0.4–1.1 mm, nectaries distinct or connate and cup-shaped;
stamens 3–9;
filaments distinct or basally connate, hairy on proximal 1/2 or basally;
anthers ellipsoid or shortly cylindrical, 0.5–0.7 mm.
adaxial nectary ovate, oblong, or flask-shaped, 0.3–1.1 mm, shorter than stipe;
stipe 1.2–2.4 mm;
ovary pyriform to obclavate, beak slightly bulged below or abruptly tapering to styles;
ovules 12–16 per ovary;
styles connate, 0.3–1 mm;
stigmas flat, abaxially non-papillate with rounded tip, or slenderly cylindrical, 0.4–0.7 mm.
7–12 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.
staminate (stout), 25–53 × 12–16 mm, flowering branchlet 5–14 mm; pistillate (fruiting in autumn, often persistent) moderately densely to loosely flowered, stout to globose, 17–42(–65 in fruit) × 11–22 mm, flowering branchlet 5–32(–65 in fruit) mm;
floral bract (sometimes greenish tawny), 1.2–4 mm, apex acute, rounded, or truncate, glandular-toothed, abaxially moderately densely hairy, hairs straight or wavy.
= 76.
Salix humboldtiana
Salix serissima
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.)
Salix serissima is found in Nunavut only on Akimiski Island in James Bay.
Flowering of Salix serissima is often described as serotinous (i.e., long after leaves emerge), but actually, they flower just as leaves emerge. Although they flower only a little later in spring than related species, they set fruit in late summer, and fruiting catkins often persist throughout winter. Their seeds remain dormant throughout the winter and germinate in the spring, thus enabling them to invade fens by completing their first annual growth before the sedges and grasses are tall enough to shade them out. This strategy has been reported to occur also in the related S. pentandra (A. K. Skvortsov 1999).
North American Salix serissima is closely related to Eurasian S. pseudopentandra (Floderus) Floderus (A. K. Skvortsov 1999), which is known in China as S. pentandra var. intermedia Nakai and possibly also S. humaensis Y. L. Chou & R. C. Chou (Fang Z. F. et al. 1999). The relationship of S. serissima and S. pseudopentandra is similar to that of S. arbusculoides and S. boganidensis (G. W. Argus 1997). These two species, along with the amphiberingian S. vestita, are relictual members of former panboreal distributions.
Hybrids:
Hybrids between Salix lucida and S. serissima have been reported (M. L. Fernald 1950); no convincing specimens have been seen.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
WildflowerSearch
iNaturalist
USDA Plants Database
BC
Go Botany
IL Wildflowers
MI Flora
MN Wildflowers
PNW Herbaria
