Salix reticulata |
Salicaceae |
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net-leaf willow, net-vein willow, netted willow |
willow family |
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Habit | Plants 0.03–0.15 m, (dwarf, forming clones by layering). | Shrubs or trees, heterophyllous or not, sometimes clonal, forming clones by root shoots, rhizomes, layering, or stem fragmentation; glabrous or glabrescent to pubescent; branching monopodial or sympodial. | ||||||||||||
Stems | trailing; branches and branchlets yellow-brown or red-brown, glabrous. |
erect to pendent; branched. |
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Leaves | stipules absent or rudimentary; petiole 3–46 mm, (sometimes glandular distally); largest medial blade amphistomatous or hemiamphistomatous, (2 pairs of secondary veins arising at or close to base, arcing toward apex), oblong, broadly oblong, broadly elliptic, subcircular, or circular, (8–)12–66 × 8–50 mm, 1–1.5 times as long as wide, base convex, rounded, subcordate, or cordate, margins slightly revolute, entire or crenulate (glandular-dotted), apex rounded, convex, or retuse, abaxial surface sparsely long-silky to glabrescent, adaxial (venation deeply impressed), slightly or highly glossy, glabrous or pilose; proximal blade margins entire; juvenile blade glabrous. |
persistent, deciduous or marcescent, alternate (opposite or subopposite in Salix purpurea), spirally arranged, simple; stipules present or not; petiole present; blade margins toothed or entire, sometimes glandular. |
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Inflorescences | racemose or spicate, usually catkins, unbranched, sometimes fasciculate or racemelike cymes, flowering before or as leaves emerge or year-round; floral bract (1) subtending each flower, displaced onto pedicel or distinct, scalelike, apex entire, toothed, or laciniate; bract subtending pistillate flower deciduous or persistent. |
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Peduncles | present or absent. |
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Pedicels | present or absent. |
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Flowers | usually unisexual, sometimes bisexual, usually staminate and pistillate on different plants; sepals present or absent, or perianth modified into 1 or 2 nectaries, or a non-nectariferous disc; stamens 1–60(–70); filaments distinct or connate basally, slender; anthers longitudinally dehiscent; ovary 1, 2–7[–10]-carpellate, 1–7[–10]-locular; placentation usually parietal, sometimes axile on intruded, fused placentae; ovules 1–25 per ovary; style 1 per carpel, distinct or connate; stigmas 2–4, truncate, notched-capitate, or 2- or 3-lobed. |
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Staminate flowers | abaxial nectary 0.5–0.9 mm, adaxial nectary oblong or ovate, 0.5–1 mm, nectaries connate and cup-shaped; filaments distinct, hairy on proximal 1/2 or throughout; anthers ellipsoid or globose, 0.3–0.4 mm. |
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Pistillate flowers | abaxial nectary (0–)0.3–0.5 mm, adaxial nectary narrowly oblong, 0.5–1 mm, equal to or longer than stipe, nectaries distinct or connate and cup-shaped; stipe 0–0.8 mm; ovary pyriform or ovoid, short-silky, hairs flattened, beak abruptly tapering to styles; ovules 8–18 per ovary; styles connate to distinct 1/2 their lengths, 0.2–0.3 mm; stigmas flat, abaxially non-papillate with rounded tip, broadly cylindrical, or 2 plump lobes, 0.2–0.26–0.36 mm. |
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Fruits | capsular, baccate, or drupaceous. |
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Capsules | 4.5–5 mm. |
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Seeds | sometimes surrounded by arillate coma of relatively long, silky hairs; endosperm scant or absent. |
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Catkins | staminate 11–54 × 4–9 mm, flowering branchlet 2–28 mm; pistillate densely flowered (more than 6 flowers), slender or stout, 11–79 × 3–8 mm, flowering branchlet 2–37 mm; floral bract tawny, 0.8–1.8 mm, apex rounded to retuse, entire, abaxially glabrous. |
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2n | = 38. |
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Salix reticulata |
Salicaceae |
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Phenology | Flowering early Jun-mid Aug. | |||||||||||||
Habitat | Arctic-alpine, polygonal tundra, dry tussock tundra, partially stabilized sand dunes, sedge meadows, Dryas tundra on alpine cliffs and ledges, snowbeds, stabilized talus slopes, white spruce woods, treed bogs | |||||||||||||
Elevation | 0-3500 m (0-11500 ft) | |||||||||||||
Distribution |
AK; CO; AB; BC; MB; NL; NT; NU; ON; QC; SK; YT; Europe; Asia (Chukotka, Russian Far East, arctic, e Siberia, Spitzbergen)
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Nearly worldwide |
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Discussion | The reported occurrence of Salix reticulata in Colorado (R. D. Dorn 1997) needs further study. Salix reticulata occurs in Europe in northern Scotland, northern Scandinavia, the Alps and other European mountains, and arctic Eurasia. The species is circumpolar except for Greenland and Iceland. A population of Salix reticulata on the Queen Charlotte Islands, with consistently glabrous ovaries, was named subsp. glabellicarpa. Some southeastern Alaska populations have plants with glabrous, partially hairy, and completely short-silky ovaries growing together. The possibility that subsp. glabellicarpa may be a hybrid or a simple mutation needs study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 50+, species ca. 1000 (4 genera, 123 species in the flora). Taxonomic placement of the Salicaceae and the genera included in it have varied greatly. Some botanists (H. G. A. Engler and K. Prantl 1887–1915) treated it as a primitive member of the Dicotyledoneae and grouped it with other families having simple, apetalous, unisexual flowers arranged in catkins, the “Amentiferae.” At about the same time, others (C. E. Bessey 1915) took a different view, regarding the simple flowers as the result of reduction, and placed the taxa in Caryophyllales. As early as 1905, H. Hallier could see that there were similarities between Salicaceae and Flacourtiaceae; at the time, he was vigorously challenged by E. Gilg (1915). A. D. J. Meeuse (1975) summarized evidence for a close relationship between these families, including wood anatomy, phytochemistry, host-parasite relationships (including rust fungi), and morphology. He concluded that the Salicaceae could be combined with the Flacourtiaceae, “perhaps as a tribe.” A. Cronquist (1988) and R. F. Thorne (1992b) placed the Salicaceae, in a narrow sense, in Violales near Flacourtiaceae. Molecular studies support a close relationship between Salicaceae and Flacourtiaceae in Malpighiales and show that Flacourtiaceae, in a broad sense, is paraphyletic. Based on a study of plastid rbcL DNA sequences, Salix and Populus were nested within a subset of 52 genera of Flacourtiaceae (M. W. Chase et al. 2002). Chase et al. proposed moving some genera from broadly circumscribed Flacourtiaceae to Salicaceae. Other studies, based on different gene sequences, came to the same conclusion (O. I. Nandi et al. 1998; V. Savolainen et al. 2000; K. W. Hilu et al. 2003; Angiosperm Phylogeny Group 2003). The discovery of the extinct fossil genus Pseudosalix (L. D. Boucher et al. 2003), from the Eocene Green River Formation of Utah, provided further support for placing some members of Flacourtiaceae in Salicaceae. The well-preserved Pseudosalix fossils, in which reproductive structures are directly associated with the leaves, occur intermixed with Populus fossils. The leaves are slender and have salicoid teeth, inflorescences are cymose, flowers are unisexual, pedicellate, tetrasepalous, and 3- or 4-carpellate, and seeds are comose, i.e., having characteristics intermediate between Salicaceae and Flacourtiaceae. The presence, in both families, of salicoid teeth is often cited in support of their close relationship (W. S. Judd 1997b; O. Nandi et al. 1998; M. W. Chase et al. 2002; H. P. Wilkinson 2007). Salicoid teeth were first recognized and defined as having the tip of the medial vein (seta) of the tooth retained as a dark, but not opaque, non-deciduous spherical callosity fused to the tooth apex and were reported to occur in Salicaceae and Idesia of the Flacourtiaceae (L. J. Hickey and J. A. Wolfe 1975). Nandi et al. reported that a broad survey of angiosperm leaves showed that salicoid teeth occur outside of Flacourtiaceae and Salicaceae only in Tetracentraceae. Isozyme and cytological evidence show that Populus and Salix are ancient polyploids (D. E. Soltis and P. S. Soltis 1990; Wang R. and Wang J. 1991). All Salix and Populus species contain salicin (R. T. Palo 1984). The genera often included in Salicaceae, in the narrow sense, are Chosenia, Populus, Salix (A. K. Skvortsov 1999), and, sometimes, Toisusu. Molecular studies (E. Leskinen and C. Alström-Rapaport 1999; T. Azuma et al. 2000) show that Chosenia is nested within Salix. H. Ohashi (2001) treated Toisusu as Salix subg. Pleuradinea Kimura and Chosenia as Salix subg. Chosenia (Nakai) H. Ohashi. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 65. | FNA vol. 7, p. 3. | ||||||||||||
Parent taxa | Salicaceae > Salix > subg. Chamaetia > sect. Chamaetia | |||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | S. reticulata var. gigantifolia, S. reticulata subsp. glabellicarpa, S. reticulata var. semicalva | |||||||||||||
Name authority | Linnaeus: Sp. Pl. 2: 1018. (1753) | Mirbel | ||||||||||||
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