Salix rotundifolia
Salix eastwoodiae
least willow, round-leaf willow
Eastwood's willow, mountain willow, Sierra willow, Sierran willow
erect;
branches yellow-green, yellow-brown, or gray-brown, glabrous;
branchlets yellow-brown or red-brown, glabrous;
branches and branchlets sometimes weakly glaucous.
(marcescent but not skeletonized), stipules usually absent or rudimentary, rarely present on late ones;
petiole (convex, or shallowly to deeply grooved, flat), 0.4–4.6(–5.5) mm, (glabrous adaxially);
largest medial blade (2 pairs of secondary veins arising at or close to base, arcing toward apex) broadly elliptic, subcircular, or circular, 1.9–16.3 × 3–10.5 mm, 0.84–1.17(–2.53) times as long as wide, base rounded or convex, margins flat, entire, ciliate, apex retuse, rounded, convex, or acute, abaxial surface glabrous, adaxial highly glossy, glabrous;
proximal blade margins entire;
juvenile blade glabrous or puberulent.
stipules foliaceous, apex acute;
petiole convex to flat, or shallowly grooved adaxially, 3–8–17 mm, pilose or villous adaxially;
largest medial blade narrowly oblong, oblong, or elliptic, 21–57–99 × 6–20–37 mm, 1.9–2.9–5 times as long as wide, base rounded, convex, subcordate, or cordate, margins flat or slightly revolute, entire or serrulate (with relatively short, slender teeth), apex acuminate, acute, or convex, abaxial surface not glaucous, pilose, short-silky, or densely woolly-tomentose to glabrescent, hairs wavy, adaxial dull or slightly glossy, sparsely to densely silky-tomentose, midrib remaining hairy;
proximal blade margins entire or serrulate;
juvenile blade yellowish green, very densely long-silky or woolly abaxially, hairs white (sometimes yellowish).
abaxial nectary 0.5–1 mm, adaxial nectary narrowly oblong or oblong, 0.8–1.4 mm, nectaries distinct;
filaments distinct or connate less than 1/2 their lengths, glabrous;
anthers ellipsoid or globose, 0.4–0.6 mm.
adaxial nectary narrowly oblong to oblong, 0.5–1.1 mm;
filaments distinct, glabrous or hairy basally;
anthers yellow or purple turning yellow, 0.5–0.9 mm.
abaxial nectary present or absent, adaxial nectary usually narrowly oblong or oblong, sometimes flask-shaped, 0.8–2 mm, longer than stipe;
stipe 0.4–0.8 mm;
ovary pyriform, glabrous or puberulent, (hairs in patches, especially on beak), beak slightly bulged below styles;
ovules 7–17 per ovary;
styles connate or slightly distinct distally, 0.5–1 mm;
stigmas flat, abaxially non-papillate with pointed tip, or slenderly or broadly cylindrical, 0.28–0.6 mm.
adaxial nectary narrowly oblong to oblong, 0.5–1.1 mm, longer than or equal to stipe;
stipe 0.2–1.6 mm;
ovary pyriform, short- or long-silky to glabrescent, beak gradually tapering to or slightly bulged below styles;
ovules 12–16 per ovary;
styles 0.5–1.5 mm;
stigmas flat, abaxially non-papillate with rounded tip, slenderly or broadly cylindrical, or 2 plump lobes, 0.18–0.39–0.76 mm (evidentially two size classes).
3.8–8.3 mm.
4–10 mm.
from subterminal buds; staminate subglobose, stout, or indeterminate, 3.3–18.5 × 2.5–12 mm, flowering branchlet 0.5–9 mm; pistillate moderately densely to loosely flowered (2–15 flowers), stout, subglobose, globose, or indeterminate, 4.5–35 × 2–17 mm, flowering branchlet 0.5–22 mm;
floral bract brown, 1.6–2.8 mm, apex rounded or retuse, entire, abaxially sparsely hairy or ciliate, hairs usually wavy, crinkled or curly, rarely straight.
flowering as leaves emerge; staminate stout or subglobose, 9.5–36.5 × 7–15 mm, flowering branchlet 1.5–7 mm; pistillate densely or moderately densely flowered, stout or subglobose, 11–51 × 8–16 mm, flowering branchlet 2–12 mm;
floral bract brown or black, 1.4–2.8 mm, apex rounded or acute, abaxially hairy, hairs straight or wavy.
= 76.
Salix rotundifolia
Salix eastwoodiae
Varieties 2 (2 in the flora).
Salix rotundifolia is closely related to S. polaris, from which it can be separated by its glabrous ovaries and fewer-flowered catkins. They also differ somewhat in leaf venation: S. rotundifolia typically having three main veins arising from the leaf base, often only one or two pair of secondary veins, and no or indistinct tertiary veins; S. polaris typically having pinnate venation, multiple secondary veins, and distinct tertiary veins. Salix rotundifolia consists of two varieties, the diploid var. dodgeana and the hexaploid var. rotundifolia. In general, var. dodgeana is a high alpine species in the southern cordillera of Wyoming and Montana, the St. Elias Mountains in Alaska and Yukon, the Mackenzie Mountains, Northwest Territories, and the Richardson Mountains, Yukon Territory. A diploid specimen of S. rotundifolia in the Cherski Mountains, Yakutia, Russia (B. A. Jurtzev and P. G. Zhukova 1982), which fits var. dodgeana in its 2–3-flowered catkins, relatively small leaves (3.5 × 3.9 mm), and small stomata (490 µm2), may represent an ancestral population. Variety rotundifolia usually occurs at lower elevations in Alaska and in easternmost Chukotka and Wrangel Island, Russia, but elevation separation is not distinct. There is a general correlation between stomatal size and ploidal level (W. Buechler, pers. comm.), but relatively large stomata in some diploid specimens of S. rotundifolia indicates a need for further cytological study. For the present, it is best to recognize the two cytotypes as varieties.
Hybrids:
Salix rotundifolia forms natural hybrids with S. arctica, S. phlebophylla, and S. polaris.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Salix eastwoodiae and S. commutata are distinct species with different ploidal levels, the former tetraploid and the latter diploid; where they come into contact in the Pacific Northwest, hybrids occur and vegetative plants are often difficult to separate. See comparison below. The most important difference is that ovaries of S. eastwoodiae usually are silky turning glabrescent in age and those of S. commutata are glabrous. Populations occur in Oregon with both glabrous and hairy ovaries without any other evident differences. There are also unusual specimens, which are often tentatively identified as S. eastwoodiae, that have glabrous ovaries and patches of hairs at the base and on the sutures. The possibility that they are hybrids between S. eastwoodiae and S. boothii, S. commutata, or S. lemmonii needs study.
Salix commutata is distinguished from S. eastwoodiae by having leaf blades sometimes amphistomatous, 1.5–3.4 times as long as wide, teeth 0–19 per cm, adaxial surfaces glabrous or pilose to villous, floral bracts tawny to brown, staminate and pistillate adaxial nectaries oblong to square, and ovaries glabrous; S. eastwoodiae has leaf blades hypostomatous, 1.8–5 times as long as wide, teeth 0–10 per cm, adaxial surfaces tomentose or long-silky, floral bracts brown to black, staminate and pistillate adaxial nectaries narrowly oblong to oblong, and ovaries silky to glabrescent.
Hybrids:
Salix eastwoodiae forms natural hybrids with S. arizonica, S. boothii, and S. commutata.
Salix eastwoodiae × S. lasiandra was found in Sierra County, California, growing with both parents in a wetland along a disturbed roadside. It had leaf indumentum and hair color of S. eastwoodiae and leaf shape and margins of S. lasiandra. Catkins of this intersubgeneric hybrid were teratological and presumably infertile.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Pistillate catkins: (3-)4-7-15 flowers; largest medial blades 4.5-8-16.3 mm, 0.92-1.23-2.27 times as long as wide; petioles 0.5-2-4.6 (-5.5) mm; floral bracts: hairs usually wavy, some straight, curly, or crinkled, exceeding bract by 0.32-0.71-1.25(-2.4) mm; pistillate flowers: abaxial nectaries present or absent; 2n = 114. | var. rotundifolia |
1. Pistillate catkins: 2-4-9 flowers; largest medial blades 2.9-6.1-7.4 mm, 0.84-1.5-2.2 times as long as wide; petioles 0.4-1.1-2.8 mm; floral bracts: hairs usually wavy, crinkled, or curly, rarely straight, exceeding bract by 0.1-0.37-0.75 mm; pistillate flowers: abaxial nectaries absent; 2n = 38. | var. dodgeana |
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