Salix interior
Salix laevigata
sandbar willow
polished willow, red willow
stipules absent or rudimentary on early ones, rudimentary or foliaceous on late ones;
petiole 1–5(–9) mm, glabrous or sparsely villous adaxially;
largest medial blade linear to lorate, 60–160 × 4–11 mm, (6.5–)11–19(–31) times as long as wide, base cuneate, margins flat, remotely spinulose-serrulate (teeth 2–5 per cm), apex acute or subacuminate, abaxial surface thinly glaucous, densely villous or long-silky to glabrescent, adaxial slightly glossy, pilose or densely villous to glabrescent;
proximal blade margins entire;
juvenile blade reddish or yellowish green, moderately densely to sparsely long-silky abaxially.
stipules rudimentary grading into foliaceous or absent on early ones, usually foliaceous on late ones, apex acute, acuminate, rounded or convex;
petiole (shallowly or deeply grooved adaxially, margins sometimes touching, sometimes with basilaminar glands, thickening), 3.5–18 mm, pubescent to glabrescent adaxially;
largest medial blade lorate, narrowly oblong, narrowly elliptic, lanceolate, or obovate, 53–190 × 11–35 mm, 2.8–9 times as long as wide, base convex, subcordate, rounded, or cuneate, margins crenate, entire, or finely serrulate, apex acuminate, acute, or caudate, abaxial surface glabrous or pubescent, hairs spreading, white and/or ferruginous, adaxial highly or slightly glossy, glabrous or pubescent, midrib sometimes villous;
proximal blade margins entire;
juvenile blade glabrous or moderately densely long-silky to pilose abaxially, hairs white and/or ferruginous.
abaxial nectary 0.5–1.1 mm, adaxial nectary ovate, narrowly oblong, or flask-shaped, 0.6–1.4 mm, nectaries distinct;
filaments hairy;
anthers 0.4–0.9 mm.
abaxial nectary 0.4–0.6 mm, adaxial nectary oblong, square, or ovate, 0.3–0.6 mm, nectaries distinct;
stamens 3–7;
filaments (sometimes basally connate), hairy on proximal 1/2 or basally;
anthers 0.4–0.6 mm.
adaxial nectary narrowly oblong, 0.4–1.1 mm, shorter to longer than stipe;
stipe 0.4–0.8 mm;
ovary obclavate to pyriform, glabrous, glabrescent, or long-silky, beak abruptly tapering to styles;
ovules 16–36 per ovary;
styles 0–0.2 mm;
stigmas flat, abaxially non-papillate with pointed tip, or broadly cylindrical, 0.3–0.7 mm.
adaxial nectary square, 0.2–0.6 mm;
stipe 1.4–2.8 mm;
ovary pyriform, obturbinate, or ellipsoidal, beak slightly bulged below styles;
ovules 12–24 per ovary;
styles 0.1–0.2 mm;
stigmas 0.2–0.23–0.28 mm.
(4–)5–8(–10) mm.
3–5.5 mm.
(flowering throughout season); staminate 20–61 × 4–10 mm, flowering branchlet 3–20 mm; pistillate loosely flowered, slender or stout, 20–67 × 5–9 mm, flowering branchlet 3–19 mm;
floral bract (sometimes greenish), 1.5–3.5 mm, apex acute, acuminate, or rounded, entire, erose, or toothed, abaxially hairy either proximally or distally, hairs wavy.
staminate 31–83 × 7–13 mm, flowering branchlet 2–26 mm; pistillate 28–79 × 6–11 mm, flowering branchlet 3–14 mm;
floral bract 1.6–3.4 mm, apex rounded or acute, irregularly toothed or entire, abaxially sparsely to moderately densely hairy proximally or throughout, hairs wavy; pistillate bract deciduous after flowering.
= 38.
Salix interior
Salix laevigata
Sometimes Salix interior is treated as a subspecies of S. exigua (R. D. Dorn 1998). Salix exigua and S. interior hybridize and apparently intergrade in the western Great Plains; because the area of overlap is relatively small and distinctiveness of the two taxa is not compromised by hybridization and introgression, it is best to treat them as separate species.
Leaves on sylleptic shoots are usually very densely silky. Salix interior sometimes has shoots that arise from buds on either side of the normal axillary bud. They do not seem to be directly related to the stipules because they are enclosed by the petiole. Catkins with both staminate and pistillate flowers are rare in S. interior, but a Quebec specimen had some catkins predominantly pistillate and others staminate; most were a mixture. The flowers were not teratological, but a mature capsule contained aborted ovules.
Hybrids:
Salix interior forms natural hybrids with S. exigua var. exigua. Controlled pollinations using S. interior (as S. exigua) from southern Ontario (A. Mosseler 1990) successfully produced F1 hybrids with S. bebbiana, S. discolor, S. eriocephala, and S. petiolaris. Seed production was usually relatively low, except in crosses with S. discolor. In general, F1 viability was relatively low in crosses with these members of subg. Vetrix. No seeds were produced in crosses with members of subgenera Protitea or Salix. Morphology of the hybrids usually was intermediate between the two parents, but when S. petiolaris was used as the maternal parent, the F1s more closely resembled that species. J. Salick and E. Pfeffer (1999) extended these findings to show that, although crosses between S. interior (as S. exigua) and S. eriocephala are partially sterile, their clonal growth parameters (sprouting, shoot length, and biomass production) are strong and thus permit these partially sterile hybrids to exist as successful individuals and perhaps to “... make a contribution to interspecific gene flow over time.” Of particular taxonomic interest is that, in this cross, the staminate parent has a significant influence on leaf shape, whereas in the cross S. eriocephala × S. petiolaris it is the pistillate parent that is significant for leaf shape. Relatively few hybrids resembling those produced by Mosseler have been recognized in nature, but it is possible that the unusually broadly leaved plants named S. interior var. exterior and var. wheeleri, from northern Maine, Nebraska, New York, and West Virginia, and probably elsewhere, may be hybrids. Phenological isolation may be strong enough to prevent crosses in nature (A. Mosseler and C. S. Papadopol 1989) with the earlier flowering S. eriocephala and S. petiolaris, a barrier that even an occasional period of overlap cannot breach.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Hybrids:
Salix laevigata forms natural hybrids with S. gooddingii.
Related Species:
Salix humboldtiana Willdenow: Humboldt willow is not known to occur in the flora area. It 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.
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.)
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