Salix interior
Salix barrattiana
sandbar willow
Barratt's 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 (sometimes marcescent), foliaceous, (resinous, 1.5–7.5 mm), apex acute;
petiole shallowly grooved, or convex to flat adaxially, 4–15 mm, villous or puberulent adaxially, (weakly ventricose around floral buds);
largest medial blade narrowly to broadly elliptic, oblanceolate, or obovate, 35–95 × 10–29 mm, 2.2–4.2(–5) times as long as wide, base usually convex, rounded, or cuneate, sometimes cordate, margins flat, entire, apex acute, convex, or acuminate, abaxial surface not glaucous, moderately to very densely long-silky tomentose to glabrescent, hairs wavy, adaxial slightly glossy, sparsely villous or pubescent to glabrescent;
proximal blade margins entire;
juvenile blade color sometimes obscured by hairs, very densely long-silky abaxially, hairs white.
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.
adaxial nectary narrowly oblong to oblong, 0.4–1.8 mm;
filaments distinct;
anthers yellow or purple turning yellow, ellipsoid or shortly cylindrical, 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 narrowly oblong to oblong, 0.6–1.3 mm;
stipe 0.2–0.6 mm;
ovary pyriform, (hairs refractive), beak gradually tapering to styles;
ovules 16–21 per ovary;
styles 0.6–1.8 mm;
stigmas 0.28–0.47–0.64 mm.
(4–)5–8(–10) mm.
4.5–6 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.
flowering before leaves emerge; staminate stout or subglobose, 20–57 × 13–18 mm, flowering branchlet 0–2 mm; pistillate densely flowered, slender to stout, 28–92(–105 in fruit) × 12–19 mm, flowering branchlet 0–5 mm;
floral bract brown or black, 2.8–5.2 mm, apex acute to convex, abaxially hairy, hairs straight.
= 38.
Salix interior
Salix barrattiana
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.)
Salix barrattiana has stipules and buds that are typically strongly oily or resinous, staining pressing sheets yellow. The Montana and Wyoming records are the basis for a conservation assessment by J. A. R. Ladyman (www.fs.fed.us/r2/projects/scp/assessments/salixbarrattiana.pdf). The Wyoming population is represented by three staminate specimens. Their buds and stipules are not conspicuously oily and further verification is needed.
Salix barrattiana is placed here in sect. Villosae, but it is morphologically similar also to members of sect. Lanatae. The most conspicuous difference is its hairy ovaries. Inconsistent phenetic clustering of this species (G. W. Argus 1997) shows the difficulty in determining its sectional placement. The suggestion that it may link the two sections by hybridization and introgression, or by alloploidy, still remains to be assessed.
Hybrids:
Salix barrattiana forms natural hybrids with S. barclayi, S. commutata, and S. pseudomyrsinites.
Salix barrattiana × S. commutata: This hybrid, known from Alberta and the Yukon, usually resembles S. barrattiana, but ovaries are hairy in patches, stipes at ca. 1 mm are long for that species, and buds and stipules are not oily. A British Columbia specimen has glabrous ovaries and oily stipules.
Salix barrattiana × S. pseudomyrsinites is a rare putative hybrid that combines characteristics of the two parents.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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