Common names: Willow Family
Treatment appears in FNA Volume 7. Treatment on page 3. Mentioned on page 4, 8, 9, 23, 29, 51.

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 erect to pendent; branched. Leaves 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. Peduncles present or absent. 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. Pedicels present or absent. 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-lobed or 3-lobed. Fruits capsular, baccate, or drupaceous. Seeds sometimes surrounded by arillate coma of relatively long, silky hairs; endosperm scant or absent.

Discussion

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.

Illustrations

 Family TaxonIllustrator 
FNA7 P1 Populus heterophylla.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Populus fremontii
Populus fremontii subsp. fremontii
Populus grandidentata
Populus tremuloides
Populus heterophylla
Populus trichocarpa
Populus balsamifera
Populus angustifolia
Populus deltoides
Populus deltoides subsp. deltoides
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FNA7 P10 Salix arctica.jpegSalicaceae
Salicaceae
Salicaceae
Salix arctica
Salix petrophila
Salix cascadensis
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FNA7 P11 Salix pedicellaris.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix pedicellaris
Salix athabascensis
Salix brachycarpa
Salix brachycarpa var. brachycarpa
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FNA7 P12 Salix niphoclada.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salix glauca var. villosa
Salix glauca var. cordifolia
Salix niphoclada
Salix glauca
Salix glauca var. stipulata
Salix glauca var. acutifolia
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FNA7 P13 Salix commutata.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salix commutata
Salix eastwoodiae
Salix wolfii
Salix wolfii var. wolfii
Salix wolfii var. idahoensis
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FNA7 P14 Salix myrtillifolia pg 109.jpegSalicaceae
Salicaceae
Salicaceae
Salix myrtillifolia
Salix arizonica
Salix boothii
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FNA7 P15 Salix barclayi.jpegSalicaceae
Salicaceae
Salicaceae
Salix barclayi
Salix pyrifolia
Salix hastata
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FNA7 P16 Salix pseudomonticola.jpegSalicaceae
Salicaceae
Salicaceae
Salix pseudomonticola
Salix myricoides
Salix eriocephala
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FNA7 P17 Salix lutea pg 124.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix lutea
Salix prolixa
Salix discolor
Salix humilis
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FNA7 P18 Salix humilis var humilis pg 130.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix humilis var. humilis
Salix humilis var. tristis
Salix scouleriana
Salix bebbiana
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FNA7 P19 Salix pellita.jpegSalicaceae
Salicaceae
Salicaceae
Salix pellita
Salix pulchra
Salix arbusculoides
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FNA7 P2 Salix floridana.jpegSalicaceae
Salicaceae
Salicaceae
Salix floridana
Salix bonplandiana
Salix laevigata
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FNA7 P20 Salix candida.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix candida
Salix calcicola
Salix calcicola var. calcicola
Salix richardsonii
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FNA7 P21 Salix tweedyi.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix tweedyi
Salix alaxensis
Salix alaxensis var. alaxensis
Salix barrattiana
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FNA7 P22 Salix argyrocarpa pg 151.jpegSalicaceae
Salicaceae
Salicaceae
Salix argyrocarpa
Salix petiolaris
Salix geyeriana
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FNA7 P23 Salix lemmonii.jpegSalicaceae
Salicaceae
Salicaceae
Salix lemmonii
Salix irrorata
Salix lasiolepis
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FNA7 P23a Salix sericea.jpegSalicaceae
Salicaceae
Salicaceae
Salix sericea
Salix sitchensis
Salix breweri
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FNA7 P24 Flacourtia indica.jpegSalicaceae
Salicaceae
Tropaeolaceae
Flacourtia indica
Xylosma flexuosa
Tropaeolum majus
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Barbara Alongi
FNA7 P3 Salix caroliniana pg 35.jpegSalicaceae
Salicaceae
Salicaceae
Salix caroliniana
Salix nigra
Salix amygdaloides
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FNA7 P4 Salix serissima.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix serissima
Salix lucida
Salix maccalliana
Salix exigua
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FNA7 P5 Salix exigua var exigua.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salix exigua var. exigua
Salix interior
Salix melanopsis
Salix vestita
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FNA7 P6 Salix reticulata.jpegSalicaceae
Salicaceae
Salicaceae
Salix reticulata
Salix nivalis
Salix setchelliana
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FNA7 P7 Salix herbacea.jpegSalicaceae
Salicaceae
Salicaceae
Salix herbacea
Salix polaris
Salix chamissonis
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FNA7 P8 Salix fuscescens.jpegSalicaceae
Salicaceae
Salicaceae
Salix fuscescens
Salix arctophila
Salix uva-ursi
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FNA7 P9 Salix ovalifolia.jpegSalicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salicaceae
Salix ovalifolia
Salix ovalifolia var. ovalifolia
Salix ovalifolia var. cyclophylla
Salix ovalifolia var. arctolitoralis
Salix ovalifolia var. glacialis
Salix jejuna
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FNA7 Populus Hybridization.jpegSalicaceaePopulusJohn Myers

Key

1 Flowers in catkins; sepals absent; fruits capsules > 2
1 Flowers not in catkins; sepals present; fruits drupes or berries > 3
2 Buds 3-10-scaled (usually resinous); leaf blades usually less than 2 times as long as wide, venation ± palmate (basal secondary veins strong, paired, except in Populus angustifolia); stipules caducous; catkins pendulous, sessile; floral bracts: apex deeply or shallowly cut, pistillate floral bracts deciduous after flowering; flowers without nectaries (with a non-glandular, cup- or saucer-like disc); stamens 6-60(-70); stigmas 2-4; capsules 2-4-valved, narrowly ovoid to spherical. Populus
2 Buds 1-scaled (oily in Salix barrattiana); leaf blades often more than 2 times as long as wide, venation usually pinnate; stipules persistent or absent; catkins erect, spreading, or ± pendulous, sessile or terminating flowering branchlets; floral bracts: apex entire, erose, 2-fid, or irregularly toothed, pistillate floral bracts persistent or deciduous after flowering; flowers: perianth reduced to adaxial nectary (rarely also with abaxial nectary, then distinct or connate into shallow cup); stamens 1, 2, or 3-10; stigmas 2; capsules 2-valved, obclavate to ovoid or ellipsoid. Salix
3 Flowers in racemelike cymes or solitary; fruits drupes, 18-25 mm Flacourtia
3 Flowers in fascicles; fruits berries, 4-7 mm. Xylosma
... more about "Salicaceae"
laciniate +, toothed +  and entire +
George W. Argus +, James E. Eckenwalder +  and Robert W. Kiger +
Mirbel +
Willow Family +
Nearly worldwide +
connate +  and distinct +
pistillate +  and staminate +
bisexual +  and unisexual +
drupaceous +, baccate +  and capsular +
unbranched +  and spicate +
arranged +  and alternate +
marcescent +
deciduous +  and persistent +
2-7[-10]-carpellate +
fisher1928a +, floderus1923a +, judd1997b +  and leskinen1999a +
branched +, sympodial +, monopodial +  and branching +
erect;pendent +
glabrescent;pubescent +
3-lobed +, 2-lobed +  and notched-capitate +
connate +  and distinct +
persistent +  and deciduous +
Salicaceae +
heterophyllous +  and not +
tree +, clonal +  and shrub +