Elaeagnus

Elaeagnus , silverberry or oleaster, is a genus of about 50–70 species of flowering plants in the family Elaeagnaceae.
Description
Elaeagnus plants are deciduous or evergreen shrubs or small trees. The alternate leaves and the shoots are usually covered with tiny silvery to brownish scales, giving the plants a whitish to grey-brown colour from a distance. The flowers are small, with a four-lobed calyx and no petals; they are often fragrant. The fruit is a fleshy drupe containing a single seed; it is edible in many species. Several species are cultivated for their fruit, including E. angustifolia, E. umbellata, and E. multiflora (gumi). E. umbellata contains the carotenoid lycopene.
Taxonomy
The genus Elaeagnus was erected in 1754 by Carl Linnaeus, who attributed the name to Joseph Pitton de Tournefort. There is agreement that the name is based on Theophrastus's use of the Ancient Greek (latinized to ) as the name of a shrub. The first part of the name, elae-, is from , 'olive'. Sources differ on the origin of the second part: it may be from , Vitex agnus-castus, the chaste tree, or from the Greek name for a kind of willow. In either case, the second part is derived from , meaning 'pure', 'chaste'.
Species
Elaeagnus comprises the following species:
Elaeagnus angustata (Rehder) C.Y.Chang (China)
Elaeagnus angustifolia L. – oleaster, Russian silverberry, or Russian olive (western Asia)
Elaeagnus annamensis S.Moore
Elaeagnus argyi H.Lév. (China)
Elaeagnus bambusetorum Hand.-Mazz. (China)
Elaeagnus bockii Diels (China)
Elaeagnus bonii Lecomte
Elaeagnus calcarea Z.R.Xu
Elaeagnus caudata Schltdl. ex Momiy.
Elaeagnus cinnamomifolia W.K.Hu & H.F.Chow (China)
Elaeagnus commutata Bernh. ex Rydb. – American silverberry or wolf-willow (North America)
Elaeagnus conferta Roxb. (southern Asia)
Elaeagnus courtoisii Belval (China)
Elaeagnus davidii Franch. (China)
Elaeagnus delavayi Lecomte (China)
Elaeagnus difficilis Servett. (China)
Elaeagnus epitricha Momiy. ex H.Ohba
Elaeagnus fasciculata Griff.
Elaeagnus formosana Nakai (Taiwan)
Elaeagnus formosensis Hatus.
Elaeagnus geniculata D.Fang
Elaeagnus glabra Thunb. (eastern Asia)
Elaeagnus gonyanthes Benth. (China)
Elaeagnus griffithii Servett. (China)
Elaeagnus grijsii Hance (China)
Elaeagnus guizhouensis C.Y.Chang (China)
Elaeagnus henryi Warb. ex Diels (China)
Elaeagnus heterophylla D.Fang & D.R.Liang
Elaeagnus hunanensis C.J.Qi & Q.Z.Lin
Elaeagnus indica Servett.
Elaeagnus infundibularis Momiy.
Elaeagnus jiangxiensis C.Y.Chang (China)
Elaeagnus jingdonensis C.Y.Chang (China)
Elaeagnus kanaii Momiy. (China)
Elaeagnus lanceolata Warb. (China)
Elaeagnus lanpingensis C.Y.Chang (China)
Elaeagnus laosensis Lecomte
Elaeagnus latifolia L. (southern Asia)
Elaeagnus lipoensis Z.R.Xu
Elaeagnus liuzhouensis C.Y.Chang (China)
Elaeagnus longiloba C.Y.Chang (China)
Elaeagnus loureiroi Champ. (southern China)
Elaeagnus luoxiangensis C.Y.Chang (China)
Elaeagnus luxiensis C.Y.Chang (China)
Elaeagnus macrantha Rehder (China)
Elaeagnus macrophylla Thunb. (eastern Asia)
Elaeagnus magna (Servett.) Rehder (China)
Elaeagnus matsunoana Makino
Elaeagnus maximowiczii Servett.
Elaeagnus micrantha C.Y.Chang (China)
Elaeagnus mollis Diels (China)
Elaeagnus montana Makino
Elaeagnus morrisonensis Hayata (Taiwan)
Elaeagnus multiflora Thunb. – cherry silverberry or gumi (eastern Asia)
Elaeagnus murakamiana Makino
Elaeagnus nanchuanensis C.Y.Chang (China)
Elaeagnus obovata H.L.Li (China)
Elaeagnus obovatifolia D.Fang
Elaeagnus obtusa C.Y.Chang (China)
Elaeagnus oldhamii Maxim. (China)
Elaeagnus ovata Servett. (China)
Elaeagnus pallidiflora C.Y.Chang (China)
Elaeagnus parvifolia Wall. ex Royle (central Asia)
Elaeagnus pilostyla C.Y.Chang (China)
Elaeagnus pingnanensis C.Y.Chang (China)
Elaeagnus pungens Thunb. – silverthorn (Japan)
Elaeagnus pyriformis Hook.f. (eastern Himalaya)
Elaeagnus retrostyla C.Y.Chang (China)
Elaeagnus rhamnoides (L.) A.Nelson
Elaeagnus rivularis Merr.
Elaeagnus rotundata Nakai
Elaeagnus sarmentosa Rehder (China)
Elaeagnus schlechtendalii Servett. (China)
Elaeagnus songarica Schltr.
Elaeagnus s-stylata Z.R.Xu
Elaeagnus stellipila Rehder (China)
Elaeagnus takeshitai Makino
Elaeagnus taliensis C.Y.Chang (China)
Elaeagnus tarokoensis S.Y.Lu & Yuen P.Yang
Elaeagnus thunbergii Servett. (China)
Elaeagnus tonkinensis Servett. (southeastern Asia)
Elaeagnus tricholepis Momiy.
Elaeagnus triflora Roxb. (southeastern Asia, northeast Australia)
Elaeagnus tubiflora C.Y.Chang (China)
Elaeagnus tutcheri Dunn (southern China)
Elaeagnus umbellata Thunb. – Japanese silverberry or autumn olive (eastern Asia)
Elaeagnus viridis Servett. (China)
Elaeagnus wenshanensis C.Y.Chang (China)
Elaeagnus wilsonii H.L.Li (China)
Elaeagnus wushanensis C.Y.Chang (China)
Elaeagnus xichouensis C.Y.Chang (China)
Elaeagnus xingwenensis C.Y.Chang
Elaeagnus xizangensis C.Y.Chang (China)
Elaeagnus yoshinoi Makino
Elaeagnus yunnanensis Servett.
Species names with uncertain taxonomic status
The status of the following species is unresolved:
Elaeagnus arakiana Koidz.
Elaeagnus asakawana Sa.Kurata
Elaeagnus attenuata Nakai
Elaeagnus crocea Nakai
Elaeagnus cyanea Aiton ex Steud.
Elaeagnus emarginata Colla
Elaeagnus fasciculata (Wall. ex Steud.) A.Nelson
Elaeagnus fragrans Nakai
Elaeagnus fruticosa (Lour.) A.Chev.
Elaeagnus fusca Pépin ex Lem.
Elaeagnus higoensis Nakai
Elaeagnus kiusiana Nakai
Elaeagnus laetevirens Lindb.
Elaeagnus latifolia Lour.
Elaeagnus mayeharai Nakai
Elaeagnus nagasakiana Nakai
Elaeagnus numajiriana Makino
Elaeagnus oleaster L.
Elaeagnus pauciflora C.Y. Chang (China)
Elaeagnus philippinensis Perrott. – lingaro berry (Philippines)
Elaeagnus × pyramidalis Browicz & Bugala (E. commutata × E. multiflora)
Elaeagnus oxycarpa Schltdl. (China)
Elaeagnus rotundifolia (Parry) A.Nelson
Elaeagnus sativa Dippel
Elaeagnus undulata auct.
Elaeagnus utilis A.Nelson
Elaeagnus veteris-castelli Lepage
Elaeagnus yakusimensis Masam.
Hybrids
The following hybrids have been described:
Elaeagnus × maritima Koidz.
Elaeagnus × reflexa E.Morren & Decne. (E. pungens × E. glabra)
Elaeagnus × submacrophylla Servett. (E. macrophylla × E. pungens)
Habitat
The vast majority of the species are native to temperate and subtropical regions of Asia. Elaeagnus triflora extends from Asia south into northeastern Australia, while E. commutata is native to North America, and Elaeagnus philippinensis is native to the Philippines. One of the Asian species, E. angustifolia, may also be native in southeasternmost Europe, though it may instead be an early human introduction there. Also, several Asiatic species of Elaeagnus have become established as introduced species in North America, with some of these species being considered invasive, or even designated as noxious, in portions of the United States.
Ecology
Elaeagnus species are used as food plants by the larvae of some Lepidoptera species including Coleophora elaeagnisella and the Gothic moths. The thorny shrubs can also provide good nesting sites for birds.
Nitrogen fixation
Many Elaeagnus species harbor nitrogen-fixing organisms in their roots, so are able to grow well in low-nitrogen soils. This ability results in multiple ecological consequences where these Elaeagnus species are present. They can become invasive in many locations where they are established as exotic species. Two species (E. pungens and E. umbellata) are currently rated as category II noxious, invasive species in many world regions and by the Florida Exotic Pest Plant Council.
Cultivation
Elaeagnus species are widely cultivated for their showy, often variegated, foliage, and numerous cultivars and hybrids have been developed.
The fruit is acidic and somewhat astringent. It makes good tarts.
Notable species and hybrids in cultivation include:-
Elaeagnus angustifolia
Elaeagnus commutata
Elaeagnus macrophylla
Elaeagnus multiflora
Elaeagnus pungens
Elaeagnus × reflexa
Elaeagnus × submacrophylla (syn. E. × ebbingei)
Elaeagnus umbellata
The hybrid Elaeagnus × submacrophylla and the cultivar 'Gilt Edge' have gained the Royal Horticultural Society's Award of Garden Merit.
References
External links
eFloras Chinese Plant list: Elaeagnus
Rosales genera