Salix geyeriana
Salix silicicola
Geyer willow, Geyer's willow
blanket-leaf willow
branches (sometimes ± brittle at base), yellow-green, gray-brown, red-brown, or violet, usually glaucous, glabrous or sparsely tomentose;
branchlets yellowish, yellow-brown, red-brown, or violet, (strongly glaucous or not), glabrous or sparsely to moderately densely pubescent, (buds caprea-type).
branches yellow-brown, gray-brown, or red-brown, not glaucous, villous in patches to glabrescent;
branchlets gray-brown or red-brown, very densely villous.
stipules usually absent or rudimentary (rarely foliaceous);
petiole convex to flat, or shallowly to deeply grooved adaxially, 2–9 mm, velvety, short-silky, or pubescent adaxially;
largest medial blade lorate, narrowly elliptic, or linear, 32–89 × 5.5–14 mm, 3.6–8.4(–11.3) times as long as wide, base cuneate or convex, margins flat or slightly revolute, entire or distantly and shallowly serrulate, apex acute to acuminate, abaxial surface glaucous, glabrous or densely short- or long-silky, hairs (white, sometimes also ferruginous), straight, adaxial slightly glossy, densely short- or long-silky, especially midrib, to glabrescent, (hairs white, sometimes also ferruginous);
proximal blade margins entire or distantly and shallowly serrulate;
juvenile blade reddish or yellowish green, densely to sparsely long- or short-silky abaxially, hairs white, sometimes also ferruginous.
stipules foliaceous, apex acute to acuminate;
petiole convex to flat adaxially, 5–12 mm, villous or tomentose adaxially, (strongly ventricose around floral buds);
largest medial blade (apparently hypostomatous but surfaces obscured by hairs), narrowly oblong, narrowly elliptic, elliptic, or obovate, 36–84 × 19–40 mm, 1.8–3.6 times as long as wide, base convex or cuneate, margins slightly revolute, entire, apex convex or acuminate, abaxial surface very densely woolly-tomentose, hairs wavy, adaxial dull, moderately to very densely, villous-tomentose;
proximal blade margins entire;
juvenile blade color obscured by hairs, very densely tomentose-woolly abaxially, hairs white.
adaxial nectary oblong, ovate, or square, 0.3–0.8(–0.9) mm;
filaments distinct, glabrous or hairy on proximal 1/2 or basally;
anthers yellow or purple turning yellow, ellipsoid or globose, 0.4–0.5(–0.6) mm.
adaxial nectary oblong to narrowly oblong, 0.6–1.5 mm;
filaments distinct;
anthers yellow, ellipsoid, 0.6–0.7 mm.
adaxial nectary oblong, square, or ovate, 0.2–1 mm;
stipe (0.4–)1–2.8 mm;
ovary pyriform (gourd-shaped), beak gradually tapering to styles;
ovules 6–12 per ovary;
styles 0.1–0.2(–0.6) mm;
stigmas flat, abaxially non-papillate with rounded or pointed tip, 0.2–0.3–0.44 mm.
adaxial nectary oblong or obtriangular, 0.5–1.1 mm;
stipe 0–0.3 mm;
ovary pyriform, beak gradually tapering to styles;
ovules 12–14 per ovary;
styles 1.2–2.2 mm;
stigmas 0.52–0.75–1 mm.
(3–)4–6 mm.
4–7 mm.
flowering (before or) as leaves emerge; staminate globose, (1–1.1–)11–18 × 6–11 mm, flowering branchlet 1–5 mm; pistillate densely to loosely flowered, subglobose to globose, 8–21 × 7–17 mm, flowering branchlet 0.5–8 mm;
floral bract tawny or brown (black), 1.2–2.8 mm, apex rounded or acute, abaxially hairy, hairs short, wavy or straight.
flowering before leaves emerge; staminate stout, 40–56 × 14–15 mm, flowering branchlet 0 mm; pistillate densely flowered, slender, 35–125(–130 in fruit) mm, flowering branchlet 0 mm;
floral bract brown or black, 2–3 mm, apex convex to rounded, abaxially hairy, hairs straight.
= 38.
= 38.
Salix geyeriana
Salix silicicola
Salix geyeriana is characterized by its dark gray appearance, slender, dark branches, narrow leaves long-silky on both surfaces, general absence of stipules, and small, subglobose catkins. Plants in the Pacific Northwest with foliaceous stipules may be hybrids or introgressants, but the other parent is unknown.
Hybrids:
Salix geyeriana forms natural hybrids with S. bebbiana, S. irrorata, S. lemmonii, S. ligulifolia, and S. pedicellaris. Alleged hybrids with S. sitchensis, based on plants from British Columbia with broader, more hairy leaves, and catkins longer than in S. geyeriana, but with the short stipes of S. sitchensis (J. K. Henry 1915), are unconvincing.
Salix geyeriana × S. irrorata: A series of specimens from Arizona usually resemble S. geyeriana but have some characters of S. irrorata: foliaceous stipules, toothed leaf margins, catkins flowering before leaves emerge, shorter stipes (0.4–1.2 mm), and longer styles (0.2–0.6 mm). They also have some unique characters: proximal leaves sometimes serrulate, leaves sometimes amphistomatous, adaxial leaf surfaces mostly with ferruginous hairs, and ovaries sometimes gourd-shaped.
Salix geyeriana × S. lemmonii is uncommon but in mixed stands of the parental species some plants resemble S. geyeriana in having relatively short, subspherical catkins, small anthers, and petioles sometimes with petiolar glands; and S. lemmonii in having leaf blades amphistomatous, margins serrulate, and foliaceous stipules on early leaves. Because the species have different chromosome numbers, hybrids may be infertile, but occasional seeds have been seen. This hybrid is known from California (Lassen and Sierra counties), Oregon (Jefferson and Lane counties), and near Victoria, British Columbia.
Salix geyeriana × S. ligulifolia: Plants in Arizona with rudimentary stipules and leaves with ferruginous hairs may be this hybrid.
Salix geyeriana × S. pedicellaris occurs in Washington. It has the white and ferruginous hairs on leaves and ovaries of S. geyeriana, and leaves glaucous adaxially with prominent 2 and 3 veins of S. pedicellaris.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Comparisons of genetic variation in Salix alaxensis var. alaxensis from British Columbia and S. silicicola from Lake Athabasca sand dunes, Saskatchewan, based on isozyme loci, fit predicted relationships between progenitor and derived taxon (B. G. Purdy and R. J. Bayer 1995). Allelic diversity of S. silicicola was a subset of that of S. alaxensis, there was less genetic variation in S. silicicola than in S. alaxensis, and interspecific genetic variation within the two species was similar and relatively very high. This suggested a recent origin for the derived S. silicicola.
Salix silicicola is a uniform population that differs from S. alaxensis in its very densely villous or tomentose leaves and branchlets. These characters seem to be an adaptation to reduce sand abrasion and water loss in a sand dune environment. It is unlikely that it would have evolved in situ but probably derived from a pre-adapted source such as the one represented by specimens of putative S. silicicola from Pelly Lake, Nunavut. The isozyme study did not include specimens from that population or of S. alaxensis from Northwest Territories from which S. silicicola is likely to have been derived. Occurrence of S. silicicola-like plants in northern continental Nunavut suggests that during the late Pleistocene, it had a wider range, which now is represented by two disjunct populations. The question of appropriate taxonomic rank for the derived taxon is still unresolved. Although S. silicicola is different from S. alaxensis in its general appearance, they are very similar genetically, and argument could be made for treating them as varieties (B. Boivin 1966b).
Hybrids:
Salix silicicola forms natural hybrids with S. brachycarpa var. psammophila.
of conservation concern
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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