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FNA | Family List | FNA Vol. 7 | Salicaceae | Salix

23. Salix sessilifolia Nuttall, N. Amer. Sylv. 1: 68. 1842.

Northwest sandbar willow Northwest sandbar willow

Salix exigua Nuttall var. sessilifolia (Nuttall) Dorn; S. fluviatilis Nutall var. sessilifolia (Nuttall) Scoggan; S. longifolia Muhlenberg var. sessilifolia (Nuttall) M. E. Jones; S. macrostachya Nuttall; S. macrostachya var. cusickii Rowlee; S. sessilifolia var. villosa Andersson

Shrubs, 3-5 m. Stems: branches gray-brown or red-brown, hairy or glabrous; branchlets red-brown, densely villous. Leaves: stipules absent or rudimentary on early ones, rudimentary or foliaceous on late ones (apex acute); petiole 1-6 mm, long-silky adaxially; largest medial blade (sometimes hypostomatous, glands submarginal), linear, lorate, narrowly elliptic, or narrowly oblanceolate, 40-120 × 7.5-16 mm, 3-8.5 times as long as wide, base cuneate or convex, margins flat, remotely spinulose-serrulate, apex acuminate, acute, or caudate, abaxial surface not glaucous, densely to sparsely long- or short-silky or villous, hairs appressed or spreading, straight or wavy, adaxial dull, sparsely long-silky or villous; proximal blade margins entire; juvenile blade yellowish green, very densely long-silky or villous abaxially. Catkins: staminate 38-45 × 6-7 mm, flowering branchlet 25-45 mm; pistillate densely flowered, slender, 40-73 × 6-7 mm, flowering branchlet 20-32 mm; floral bract (sometimes brown), 2.4-3.2 mm, apex acute or rounded, entire or irregularly toothed, abaxially hairy, hairs wavy. Staminate flowers: abaxial nectary 0.4-1 mm, adaxial nectary narrowly oblong, oblong, or flask-shaped, 0.5-1.1 mm, nectaries distinct; filaments hairy on proximal 1/2; anthers 0.8-1.2 mm. Pistillate flowers: adaxial nectary oblong, square, ovate, or flask-shaped, 0.6-1 mm, longer than stipe; stipe 0.2-0.7 mm; ovary pyriform, villous or long-silky, beak abruptly tapering to styles; ovules 24-36 per ovary; styles 0.1-0.7 mm; stigmas flat, abaxially non-papillate with pointed tip, or slenderly cylindrical, 0.4-1 mm. Capsules 4-5.5 mm.

Flowering late Apr-late May. Riparian, streamshores, floodplains, sandy or gravelly substrates; 0-200 m; B.C.; Oreg., Wash.

Hybrids:

Salix sessilifolia forms natural hybrids with S. columbiana and S. melanopsis.

Excluded species:

Salix microphylla Schlechtendal & Chamisso occurs only in Mexico and Guatemala. (See 17. S. taxifolia for comments on its nomenclature.) It is characterized by: shrubs or trees, 0.8-6 m; stipules on late leaves foliaceous; largest medial blade amphistomatous, lorate, narrowly oblong, or narrowly oblanceolate, 5.6-24 × 1.2-3.8 mm, 2.1-13.3 times as long as wide, margins entire or serrulate; staminate abaxial nectary absent; stipes 0.2-1.2 mm; ovary pyriform, long-silky; ovules 21-43 per ovary; style 0.2-0.3 mm; stigmas persistent, slenderly cylindrical lobes, 0.6-0.75-0.92 mm; capsules 4-7 mm (Mexico, Central America [Guatemala]).


 

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