Salix hastata |
Salix rotundifolia |
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halberd willow |
least willow, round-leaf willow |
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Habit | Plants 0.2–4 m. Stems: branches reddish brown, not glaucous, (slightly glossy), pilose; branchlets yellow-brown or red-brown, villous or pilose. | Plants 0.005–0.05 m, (dwarf), forming clones by rhizomes. | ||||
Stems | erect; branches yellow-green, yellow-brown, or gray-brown, glabrous; branchlets yellow-brown or red-brown, glabrous; branches and branchlets sometimes weakly glaucous. |
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Leaves | stipules foliaceous, apex acute to acuminate; petiole convex to flat, or shallowly grooved adaxially, 2–6(–9) mm, pilose or villous adaxially; largest medial blade narrowly to broadly elliptic or narrowly ovate to ovate, 25–92 × 10–45 mm, 1.5–2.6(–3.4) times as long as wide, base convex, cuneate, or rounded, margins slightly revolute or flat, shallowly serrulate or entire, apex acuminate, acute, or convex, abaxial surface glaucous, sparsely pubescent, hairs wavy, adaxial dull to slightly glossy, pilose, sparsely pubescent or glabrous, midrib hairy, (hairs white and ferruginous); proximal blade margins entire or finely serrulate; juvenile blade sometimes reddish, sparsely pubescent abaxially, hairs white, sometimes also ferruginous. |
(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. |
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Staminate flowers | adaxial nectary oblong or square, 0.3–0.7 mm; filaments distinct or basally connate, glabrous; anthers purple turning yellow, 0.4–0.6 mm. |
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. |
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Pistillate flowers | adaxial nectary square or obovate, 0.3–0.6 mm, usually shorter than stipe; stipe 0.4–1.2 mm; ovary pyriform, glabrous, beak gradually tapering to styles; ovules 12–22 per ovary; styles connate (sometimes distinct 1/2 their lengths), 0.2–0.5 mm; stigmas flat, abaxially non-papillate with rounded tip, or broadly cylindrical, or 2 plump lobes, 0.2–0.32–0.44 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. |
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Capsules | 3.2–8 mm. |
3.8–8.3 mm. |
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Catkins | flowering as leaves emerge; staminate slender, stout, or subglobose, 14.5–34.5 × 8–12 mm, flowering branchlet 1–7 mm; pistillate moderately densely or loosely flowered, slender or stout, 21–59 × 6–16 mm, flowering branchlet 1.5–9 mm; floral bract brown or bicolor, 1.2–1.8 mm, apex acute to rounded, abaxially glabrate to hairy, hairs straight to wavy. |
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. |
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2n | = 38. |
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Salix hastata |
Salix rotundifolia |
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Phenology | Flowering early Jun-late Jul. | |||||
Habitat | Sandy and gravelly river bars and floodplains, lakeshores, sand dunes and blowouts, Dryas tundra, alpine sedge meadows, balsam poplar thickets, openings in upland spruce-willow forests | |||||
Elevation | 0-1200 m (0-3900 ft) | |||||
Distribution |
AK; NT; YT; Eurasia (Norway, Russia, Siberia) |
AK; MT; WY; NT; YT; e Asia
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Discussion | Salix hastata is characterized by branches pilose with short, curved hairs; juvenile and mature leaves with white or ferruginous hairs adaxially, glaucous or not abaxially; and ovaries often reddish. See 61. S. barclayi and 64. S. farriae. Subspecies subintegrifolia, characterized by entire or subentire leaf margins, is recognized in Flora Nordica as the major northern Eurasian race of Salix hastata, and is described as occurring across Russia into northwestern North America (B. Jonsell and T. Karlsson 2000+, vol. 1). Because leaf marginal toothing is highly variable throughout the species range (E. Hultén 1967), the subspecies is not recognized here or in Russia (A. K. Skvortsov 1999). Hybrids: Salix hastata forms natural hybrids with S. barclayi. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 7, p. 116. | FNA vol. 7, p. 69. | ||||
Parent taxa | Salicaceae > Salix > subg. Vetrix > sect. Hastatae | Salicaceae > Salix > subg. Chamaetia > sect. Herbella | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | S. farriae var. walpolei, S. hastata subsp. subintegrifolia, S. walpolei | |||||
Name authority | Linnaeus: Sp. Pl. 2: 1017. (1753) | Trautvetter: Nouv. Mém. Soc. Imp. Naturalistes Moscou 2: 304, plate 11. (1832) | ||||
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