Salix

White willow Salix alba, photographed by Willow.

Belongs within: Salicaceae.

Salix, the willows, is a genus of wind-pollinated trees and shrubs found mostly in arctic to temperate regions. Many species are grown as ornamentals and some have become widely invasive outside their native ranges. These include the weeping willow S. babylonica, a native of northeastern Asia of which selected varieties are grown for their pendulous habit.

Characters (from George W. Argus): Shrubs or trees, slightly heterophyllous, clonal or not, clones formed by root shoots, rhizomes, layering, or stem fragmentation; branching sympodial. Stems not spinose. Buds 1-scaled (rarely oily), margins connate into calyptra or distinct and overlapping adaxially, scale inner membranaceous layer usually not separating from outer layer, sometimes free and separating). Leaves deciduous or marcescent; stipules persistent, caducous, or absent (varying in presence and size on early and late leaves); petiole glandular-dotted or lobed distally; (blade often more than twice as long as wide, venation usually pinnate, margins entire, crenulate, crenate, serrate, serrulate, or spinulose-serrulate, teeth gland-tipped). Inflorescences axillary or subterminal, catkins, erect, spreading, or ± pendulous, sessile or terminating flowering branchlets, usually unbranched; floral bract apex entire, erose, bifid, or irregularly toothed; pistillate bract persistent or deciduous after flowering. Pedicels present or absent. Flowers: (sessile), perianth reduced to adaxial nectary (rarely also abaxial nectary, then distinct or connate into shallow cup); stamens 1, 2, or 3-10; filaments distinct or connate; ovary (stipitate or sessile), 2-carpellate; ovules (2-)4-24(-42) per ovary; styles usually connate, sometimes distinct distally; stigmas 2, entire or 2-lobed (less than 2 mm). Fruits capsular, (2-valved, obclavate to ovoid or ellipsoid). Seeds: aril present. x = 19.

<==Salix [incl. Chosenia] T00
    |--S. subg. Salix K07c
    |    |  i. s.: S. babylonica Linnaeus 1753 K05 [incl. S. japonica LO98]
    |    |--S. sect. Salix K07c
    |    |    |--S. alba Linnaeus 1753 K07c
    |    |    |    |--S. a. var. alba V09
    |    |    |    `--S. a. var. vitellina V09
    |    |    |--S. fragilis Linnaeus 1753 K07c
    |    |    |    |--S. f. var. fragilis V09
    |    |    |    `--S. f. var. russelliana V09
    |    |    `--S. × rubens Schrank 1789 K07c [S. fragilis × S. alba K07a]
    |    |         |--S. r. nothvar. rubens V09
    |    |         `--S. r. nothvar. basfordiana [S. alba var. vitellina × S. fragilis] V09
    |    |--S. (sect. Amygdalinae) triandra Linnaeus 1753 K05
    |    `--S. (sect. Pentandrae) pentandra Linnaeus 1753 K07c
    |--S. subg. Chametia K07c
    |    |--S. (sect. Chamaetia) reticulata Linnaeus 1753 K07c
    |    |    |--S. r. ssp. reticulata H93
    |    |    `--S. r. ssp. nivalis H93
    |    |--S. sect. Glaucae K07c
    |    |    |--S. glauca Linnaeus 1753 K07c
    |    |    `--S. glaucosericea Floderus 1943 K07c
    |    |--S. (sect. Myrtilloides) myrtilloides Linnaeus 1753 K06
    |    `--S. (sect. Retusae) retusa Linnaeus 1763 K07c
    `--S. subg. Vetrix K07c
         |  i. s.: S. helix [S. purpurea × S. viminalis] K07a
         |         S. × smithiana [S. cinerea × S. viminalis] V09
         |--S. sect. Vetrix K07c
         |    |--S. appendiculata Villars 1789 K07c
         |    |--S. atrocinerea Brotero 1804 K05
         |    |--S. aurita Linnaeus 1753 K07c
         |    |--S. caprea Linnaeus 1753 K07c
         |    |--S. cinerea Linnaeus 1753 K07c
         |    |    |--S. c. ssp. cinerea V09
         |    |    `--S. c. ssp. oleifolia V09
         |    `--S. × reichardtii [S. caprea × S. cinerea] V09
         |--S. sect. Arbuscella K07c
         |    |--S. foetida Schleich ex de Candolle 1805 K05
         |    |--S. phylicifolia Linnaeus 1753 K07c
         |    `--S. waldsteiniana Willdenow 1806 K05
         |--S. sect. Daphnella K07c
         |    |--S. acutifolia Willdenow 1806 K07c
         |    `--S. daphnoides Villars 1789 K07c
         |--S. (sect. Hastatae) hastata Linnaeus 1753 K07c
         |--S. (sect. Helix) purpurea Linnaeus 1753 K07c
         |--S. sect. Nigricantes K07c
         |    |--S. mielichhoferi Sauter 1849 K07c
         |    `--S. myrsinifolia Salisbury 1796 K07c
         |--S. sect. Villosae K07c
         |    |--S. helvetica Villars 1789 K07c
         |    `--S. lapponum Linnaeus 1753 K07c
         `--S. (sect. Vimen) viminalis Linnaeus 1753 K07c

Salix incertae sedis:
  S. acuminata Miller 1768 K07b
  S. amygdalina A81
  S. amygdaloides B75
  S. annularis C55b
  S. arctica Pallas 1788 K07c [incl. S. anglorum var. antiplasta H93, S. anglorum var. petraea H93]
  S. anticecrenata [incl. S. anticecrenata mstr. monadelpha] O88
  S. bebbiana H93
  S. bhutanensis O88
  S. boothii [incl. S. pseudocordata] H93
  S. brachycarpa H93
  S. breweri H93
  S. buergeriana LO98
  S. caesia C55a
  S. calyculata O88
  S. capraea RCT96
  S. caroliniana M83
  S. cascadensis H93
  S. daltoniana O88
  S. delnortensis H93
  S. discolor SF96
  S. drummondiana [incl. S. drummondiana var. subcoerulea] H93
  S. eastwoodiae H93
  S. elaeagnos K06
  S. eriocephala SF96
  S. eriostachya O88
  S. exigua (see below for synonymy) H93
  S. geyeriana [incl. S. geyeriana var. argentea] H93
  S. gooddingii [incl. S. gooddingii var. variabilis] H93
  S. herbacea CS77
  S. hookeriana [incl. S. piperi] H93
  S. humboldtiana F11
  S. hylematica O88
  S. interior B75
  S. jacquiniana C55a
  S. jepsonii [incl. S. sitchensis var. angustifolia, S. sitchensis var. ralphiana] H93
  S. karelinii O88
  S. kirilowiana S00
  S. laevigata [incl. S. laevigata var. araquipa] H93
  S. lasiolepis (see below for synonymy) H93
  S. laurina D37
  S. lemmonii H93
  S. ligulifolia H93
  S. lindleyana O88
    |--S. l. var. lindleyana O88
    `--S. l. var. microphylla O88
  S. lucida H93
    |--S. l. ssp. lucida H93
    |--S. l. ssp. caudata [incl. S. caudata var. bryantiana] H93
    `--S. l. ssp. lasiandra [incl. S. lasiandra var. abramsii, S. lasiandra var. lancifolia] H93
  S. lutea [incl. S. lutea var. watsonii] H93
  S. melanopsis [incl. S. melanopsis var. watsonii] H93
  S. myrsinites C55b
  S. myrtillacea O88
  S. nigra BV06
  S. oreophila O88
  S. orestera H93
  S. ovatomicrophylla O88
  S. pedicellata R-CT01
  S. planifolia [incl. S. phylicifolia var. monica] H93
  S. prolixa [incl. S. mackenzieana] H93
  S. psilostigma O88
  S. pycnostachya O88
  S. repens Linnaeus 1753 K05
  S. rosmarinifolia K06
  S. sclerophylla O88
  S. scouleriana [incl. S. scouleriana var. coetanea] H93
  S. sericea SF96
  S. sericocarpa O88
  S. serpyllum O88
  S. sessilifolia [incl. S. parksiana] H93
  S. sikkimensis O88
  S. silesiaca Willdenow 1806 K05
  S. sitchensis [incl. S. coulteri] H93
  S. sphenophylla Skvortsov 1966 K07c
  S. subfragilis [incl. S. nipponica] LO98
  S. tetraphylla P03
  S. tetrasperma M72
  S. varians Goeppert 1855 HL08
  S. wallichiana SS72

Salix exigua [incl. S. hindsiana, S. hindsiana var. leucodendroides, S. hindsiana var. parishiana, S. exigua var. stenophylla] H93

Salix lasiolepis [incl. S. lasiolepis var. bigelovii, S. lasiolepis var. bracelinae, S. lutea var. nivaria, S. lasiolepis var. sandbergii, S. tracyi] H93

*Type species of generic name indicated

REFERENCES

[A81] Adler, H. 1881. Les Cynipides. 1^re partie. Introduction. La génération alternante chez les cynipides, traduit et annoté par J. Lichtenstein, suivi de la classification des cynipides d'après le D^r G. Mayr. C. Coulet: Montpellier.

[B75] Bowles, J. B. 1975. Distribution and biogeography of mammals of Iowa. Special Publications, The Museum, Texas Tech University 9: 1–184.

[BV06] Brack, V., Jr & R. K. La Val. 2006. Diet of the gray myotis (Myotis grisescens): variability and consistency, opportunism, and selectivity. Journal of Mammalogy 87 (1): 7–18.

[C55a] Candolle, A. de. 1855a. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 1. Librairie de Victor Masson: Paris.

[C55b] Candolle, A. de. 1855b. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.

[CS77] Cramp, S., & K. E. L. Simmons (eds) 1977. Handbook of the Birds of Europe, the Middle East and North Africa: The Birds of the Western Palaearctic vol. 1. Ostrich to Ducks. Oxford University Press: Oxford.

[D37] Dobzhansky, T. 1937. Genetics and the Origin of Species. Columbia University Press: New York.

[F11] Fraga, R. M. 2011. Family Icteridae (New World blackbirds). In: Hoyo, J. del, A. Elliott & D. A. Christie (eds) Handbook of the Birds of the World vol. 16. Tanagers to New World Blackbirds pp. 684–807. Lynx Edicions: Barcelona.

[HL08] Henniger, M., & R. Leder. 2008. Eozäne Makroflora der Querfurter Mulde. Mauritiana 20 (2): 229–251.

[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).

[K05] Kopelke, J.-P. 2005. The species of the Pontania proxima group in Europe (Hymenoptera, Tenthredinidae, Nematinae). Senckenbergiana Biologica 85 (1): 85–95.

[K06] Kopelke, J.-P. 2006. Description of the female of Euura myrtilloides Kopelke 1996, with a key to the European species of the atra-group (Hymenoptera, Tenthredinidae, Nematinae). Senckenbergiana Biologica 86 (1): 75–84.

[K07a] Kopelke, J.-P. 2007a. The European species of the genus Phyllocolpa, part I: the leucosticta-group (Insecta, Hymenoptera, Tenthredinidae, Nematinae). Senckenbergiana Biologica 87 (1): 75–109.

[K07b] Kopelke, J.-P. 2007b. The European species of the genus Phyllocolpa, part II: the leucaspis-group (Insecta, Hymenoptera, Tenthredinidae, Nematinae). Senckenbergiana Biologica 87 (2): 149–161.

[K07c] Kopelke, J.-P. 2007c. The European species of the genus Phyllocolpa, part III: the species-groups of crassispina, scotaspis, and piliserra (Insecta, Hymenoptera, Tenthredinidae, Nematinae). Senckenbergiana Biologica 87 (2): 163–183.

[LO98] Lack, H. W., & H. Ohba. 1998. Die Xylothek des Chikusai Kato. Willdenowia 28: 263–276.

[M72] Mitra, S. N. 1972. Observations on the vegetation of the Upper Damodar catchment area. Journal of the Bombay Natural History Society 69 (1): 17–25.

[M83] Myers, R. L. 1983. Site susceptibility to invasion by the exotic tree Melaleuca quinquenervia in southern Florida. Journal of Applied Ecology 20: 645–658.

[O88] Ohba, H. 1988. The alpine flora of the Nepal Himalayas: an introductory note. In: Ohba, H., & S. B. Malla (eds) The Himalayan Plants vol. 1. The University Museum, University of Tokyo, Bulletin 31: 19–46.

[RCT96] Ragusa Di Chiara, S., & H. Tsolakis. 1996. A. survey of phytoseiid mites (Phytoseiidae) associated with various plants in Sicily (Italy). In: Mitchell, R., D. J. Horn, G. R. Needham & W. C. Welbourn (eds) Acarology IX vol. 1. Proceedings pp. 253–256. Ohio Biological Survey: Columbus (Ohio).

[R-CT01] Ragusa-di Chiara, S., & H. Tsolakis. 2001. Phytoseiid faunas of natural and agricultural ecosystems in Sicily. In: Halliday, R. B., D. E. Walter, H. C. Proctor, R. A. Norton & M. J. Colloff (eds) Acarology: Proceedings of the 10^th International Congress pp. 522–529. CSIRO Publishing: Melbourne.

[S00] Siddiqi, M. R. 2000. Tylenchida: Parasites of plants and insects 2^nd ed. CABI Publishing: Wallingford (UK).

[SS72] Singh, V., & H. Singh. 1972. A contribution to the flora of Gangolihat block in Pithoragarh District. Journal of the Bombay Natural History Society 69 (2): 352–368.

[SF96] Smith, D. R., & R. S. Fritz. 1996. Review of the eastern United States species of the leaf-folding sawflies of the genus Phyllocolpa Benson (Hymenoptera: Tenthredinidae). Proceedings of the Entomological Society of Washington 98 (4): 695–707.

[T00] Thorne, R. F. 2000. The classification and geography of the flowering plants: dicotyledons of the class Angiospermae (subclasses Magnoliidae, Ranunculidae, Caryophyllidae, Dilleniidae, Rosidae, Asteridae, and Lamiidae). The Botanical Review 66: 441–647.

[V09] Verdcourt, B. (ed.) 2009. Additions to the wild fauna and flora of the Royal Botanic Gardens, Kew. XXVI. Miscellaneous records. Kew Bulletin 64 (1): 183–194.

Last updated: 1 January 2022.