Epilobium

Epilobium is a genus of flowering plants in the family Onagraceae, containing about 197 species. The genus has a worldwide distribution. It is most prevalent in the subarctic, temperate and subantarctic regions, whereas in the subtropics and tropics Epilobium species are restricted to the cool montane biomes, such as the New Guinea Highlands.
The taxonomy of the genus has varied between different botanists, but the modern trend is to include the previously recognised genera Boisduvalia, Chamaenerion (previously Chamerion), Pyrogennema and Zauschneria within Epilobium according to Peter H. Raven, who has extensively studied the willowherbs and merges the other segregate genera into Epilobium. Fringed willowherb (Epilobium ciliatum) is likely a cryptic species complex; apparently these plants also commonly hybridize with their congeners.
Most species are known by the common name willowherbs for their willow-like leaves. Those that were once separated in Boisduvalia are called spike-primroses or boisduvalias. Those Epilobium species previously placed in the Chamaenerion group are known as fireweeds.
Description
Epilobiums are mostly herbaceous plants, either annual or perennial; a few are subshrubs. The leaves are opposite or rarely whorled, simple and ovate to lanceolate in shape. The flowers are actinomorphic (radially symmetrical) with four petals that may be notched. These are usually smallish and pink in most species, but red, orange or yellow in a few. The fruit is a slender cylindrical capsule containing numerous seeds embedded in fine, soft silky fluff which disperses the seeds very effectively in the wind.
The genus name derives from the Greek words "epi" meaning "upon" and "lobos" meaning "lobe", with reference to position of the petals above the ovary.
A number of Epilobium species with slightly asymmetrical (zygomorphic) magenta flowers and alternate leaves are placed in a Chamaenerion group, and are futher separated by some authorities into a genus Chamerion. However, Chamerion has not been universally accepted.<ref name=TPL>{{cite web |url=http://www.theplantlist.org/tpl1.1/search?q=Chamerion |title=The Plant List: Chamerion |access-date=22 February 2017}}</ref>
Habitat and ecology
Willowherbs sensu lato are typically very quick to carpet large swathes of ground and may become key or dominant species of local ecosystems. In the United Kingdom, for example, rosebay willowherb (Chamaenerion angustifolium) is widely found on mesotrophic soils dominated by false oat-grass (Arrhenatherum elatius), cock's-foot grass (Dactylis glomerata), and red fescue (Festuca rubra), while great willowherb (Epilobium hirsutum) is found in mesotrophic grassland with stinging nettle (Urtica dioica). These two willowherb species also dominate open habitat early in ecological succession, to the virtual exclusion of other plant life. Broad-leaved willowherb (Epilobium montanum) is found characteristically, though not abundantly, in the mesotrophic grasslands with meadowsweet (Filipendula ulmaria) and sometimes the uncommon Greek valerian (Polemonium caeruleum). Most willowherbs will not tolerate shade trees and thus are limited to more recently disturbed patches, yielding to other plants over time. Consequently, though the genus contains many pioneer plants, rather few of them are invasive weeds of major importance.Epilobium species are used as food plants by the caterpillars of certain Lepidoptera species, including:
Geometridae
Grey pug (Eupithecia subfuscata), recorded on several species
Noctuidae
Mouse moth (Amphipyra tragopoginis), recorded on several species
Small angle shades (Euplexia lucipara), recorded on several species
Australian grapevine moth (Phalaenoides glycinae), recorded on fringed willowherb (E. ciliatum)
Sphingidae
Elephant hawk-moth (Deilephila elpenor), recorded on several species
Small elephant hawk-moth (Deilephila porcellus), recorded on several species
White-lined sphinx (Hyles lineata), recorded on several species
Use by humans
The main use of Epilobium by humans is as a herbal supplement in the treatment of prostate, bladder (incontinence) and hormone disorders.
Many of the small willowherb species are nuisance weeds in gardens. Though few are regularly used as ornamental plants, the larger willowherbs may be attractive in ruderal locales. One of the most frequently recognized members of the genus is the circumboreal fireweed (E. angustifolium), known as rosebay willowherb in the United Kingdom. It rapidly colonizes burnt ground; during the bombing of London in World War II many of the derelict bomb sites were soon covered with these plants, bringing a splash of colour to what was otherwise a very grim scene. It is the floral emblem of Yukon in Canada, Hedmark in Norway and Southern Ostrobothnia in Finland.
Fireweed is used as a sweetener in north-western North America. It is put in candy, jellies, ice cream, syrup, and sxusem ("Indian ice cream"). In the late summer its flowers yield pollen and copious nectar which give a rich spicy honey. Its young leaves, roots, and shoots are edible (if somewhat bitter), and rich in provitamin A and vitamin C. The Dena’ina found them also useful as food supplement for dogs and applied sap from the stem to wounds, believing it to have antiinflammatory properties.
Several researchers have studied this taxon. Heinrich Carl Haussknecht in the late 19th century and Peter H. Raven about a century later researched the phylogeny, systematics, and taxonomy of willowherbs. Peter Michaelis' studies of this genus paved the way for understanding of extranuclear inheritance in plants.
Species
The following species are recognised in the genus Epilobium:
Epilobium × abortivum Epilobium × aggregatum Epilobium aitchisonii Epilobium algidum Epilobium alpestre Epilobium alsinifolium – chickweed willowherbEpilobium alsinoides Epilobium × amphibolum Epilobium amurense Epilobium anagallidifolium – alpine willowherb, pimpernel willowherbEpilobium anatolicum Epilobium anglicum Epilobium angustifolium Epilobium angustum Epilobium arcticum – Arctic willowherbEpilobium × argillaceum Epilobium arvernense Epilobium × aschersonianum Epilobium astonii Epilobium atlanticum Epilobium australe Epilobium barbeyanum Epilobium billardiereanum – glabrous willowherbEpilobium blinii Epilobium × boissieri Epilobium × borbasianum Epilobium × brachiatum Epilobium brachycarpum – tall willowherb, tall annual willowherb, tall fireweed, panicled willowherbEpilobium brevifolium Epilobium brevipes Epilobium × brevipilum Epilobium brevisquamatum Epilobium × brunnatum Epilobium brunnescens – New Zealand willowherbEpilobium campestre – pygmy willowherb, smooth boisduvaliaEpilobium canum – Zauschneria, California-fuchsia, hummingbird flower, hummingbird trumpetEpilobium capense Epilobium × celakovskyanum Epilobium × chateri Epilobium chionanthum Epilobium chitralense Epilobium chlorifolium Epilobium ciliatum – fringed willowherb, American willowherbEpilobium clarkeanum Epilobium clavatum – talus willowherb, clavatefruit willowherbEpilobium cleistogamum – selfing willowherbEpilobium cockayneanum Epilobium colchicum Epilobium collinum Epilobium coloratum – purpleleaf willowherbEpilobium confertifolium Epilobium × confine Epilobium × confusilobum Epilobium confusum Epilobium conjungens Epilobium conspersum Epilobium × cornubiense Epilobium crassum Epilobium curtisiae Epilobium cylindricum Epilobium × dacicum Epilobium × dasycarpum Epilobium davuricum – Daurian willowherbEpilobium × decipiens Epilobium densiflorum – denseflower willowherb, dense spike-primrose, dense boisduvaliaEpilobium densifolium Epilobium densum – downy willowherb, stiff spike-primroseEpilobium denticulatum Epilobium detznerianum Epilobium dodonaei Epilobium duriaei Epilobium elegans Epilobium × erroneum Epilobium × fallacinum Epilobium fangii Epilobium fastigiatoramosum Epilobium fauriei Epilobium × finitimum Epilobium fleischeri Epilobium × floridulum Epilobium forbesii Epilobium × fossicola Epilobium fragile Epilobium fugitivum Epilobium gemmascens Epilobium × gemmiferum Epilobium × gerstlaueri Epilobium glabellum – smooth spike-primroseEpilobium glaberrimum – glaucous willowherbEpilobium glaciale Epilobium × glanduligerum Epilobium glaucum Epilobium × goerzii Epilobium gouldii Epilobium gracilipes Epilobium × grenieri Epilobium griffithianum Epilobium gunnianum Epilobium × gutteanum Epilobium hallianum – glandular willowherbEpilobium × haussknechtianum Epilobium × haynaldianum Epilobium × hectori-leveilleanum Epilobium hectorii Epilobium × heterocaulon Epilobium hirsutum – great willowherb, great hairy willowherb, hairy willowherb, codlins-and-cream, apple-pie, cherry-pieEpilobium hirtigerum Epilobium hohuanense Epilobium hooglandii Epilobium hornemannii – Hornemann's willowherbEpilobium howellii – Yuba Pass willowherb, subalpine fireweedEpilobium × huteri Epilobium indicum Epilobium insulare Epilobium × interjectum Epilobium × intersitum Epilobium × jinshaense Epilobium karsteniae Epilobium × keredjense Epilobium kermodei Epilobium keysseri Epilobium kingdonii Epilobium × kitcheneri Epilobium komarovianum – bronzy willowherbEpilobium komarovii Epilobium korshinskyi Epilobium × krausei Epilobium lactiflorum – milkflower willowherb, whiteflower willowherbEpilobium ladakhianum Epilobium laestadii Epilobium × lamotteanum Epilobium lanceolatum – spear-leaved willowherbEpilobium × langeanum Epilobium × laschianum Epilobium latifolium Epilobium laxum Epilobium leiophyllum Epilobium leptocarpum – slenderfruit willowherbEpilobium leptophyllum – bog willowherb, linear-leaved willowherbEpilobium × limosum Epilobium lipschitzii Epilobium luteum – yellow willowherbEpilobium macropus Epilobium margaretiae Epilobium × marshallianum Epilobium matthewsii Epilobium maysillesii Epilobium melanocaulon Epilobium × mentiens Epilobium microphyllum Epilobium minutiflorum Epilobium minutum – chaparral willowherb, desert willowherb, smallflower willowherbEpilobium mirabile – Olympic Mountain willowherbEpilobium × montaniforme Epilobium montanum – broad-leaved willowherbEpilobium nanhualpinum Epilobium nankotaizanense – Nankotaizan willowherbEpilobium × neogradiense Epilobium nerterioides Epilobium nevadense – Nevada willowherbEpilobium nivale Epilobium nivium – Snow Mountain willowherbEpilobium × novae-civitatis Epilobium nummulariifolium Epilobium nutans Epilobium × nutantiflorum Epilobium obcordatum – rockfringe willowherbEpilobium × obscurescens Epilobium obscurum – dwarf willowherb, short-fruited willowherbEpilobium oreganum – Grants Pass willowherb, Oregon fireweedEpilobium oregonense – Oregon willowherbEpilobium × palatinum Epilobium pallidiflorum Epilobium pallidum – largeflower spike-primroseEpilobium palustre – marsh willowherbEpilobium pannosum Epilobium parviflorum – small-flowered willowherb, hoary willowherbEpilobium pedicellare Epilobium pedunculare – rockery willowherbEpilobium pengii Epilobium × percollinum Epilobium pernitens Epilobium perpusillum Epilobium × persicinum Epilobium petraeum Epilobium pictum Epilobium platystigmatosum Epilobium ponticum Epilobium porphyrium Epilobium × prionophylloides Epilobium prostratum Epilobium pseudorubescens Epilobium × pseudotrigonum Epilobium psilotum Epilobium pubens Epilobium puberulum Epilobium × pulchrum Epilobium purpuratum Epilobium × purpureum Epilobium pycnostachyum Epilobium pyrricholophum Epilobium ravenii – leafy willowherb, California willowherbEpilobium rechingeri Epilobium × reedii Epilobium rhynchospermum Epilobium rigidum – stiff willowherb, Siskiyou Mountains willowherbEpilobium × rivulare Epilobium × rivulicola Epilobium roseum – pale willowherbEpilobium rostratum Epilobium rotundifolium Epilobium royleanum Epilobium rubromarginatum Epilobium salignum Epilobium sarmentaceum Epilobium saximontanum – Rocky Mountain willowherbEpilobium × schmidtianum Epilobium × schulzeanum Epilobium semiamplexicaule Epilobium septentrionale – northern willowherb, Humboldt County fuchsiaEpilobium × sericeum Epilobium sikkimense Epilobium × similatum Epilobium × simulatum Epilobium sinense Epilobium siskiyouense – Siskiyou willowherb, Siskiyou fireweedEpilobium smithii Epilobium speciosum Epilobium spitianum Epilobium staintonii Epilobium stereophyllum Epilobium stevenii Epilobium stracheyanum Epilobium subalgidum Epilobium subcoriaceum Epilobium subdentatum Epilobium suffruticosum – shrubby willowherbEpilobium × surreyanum Epilobium taiwanianum Epilobium tasmanicum Epilobium tetragonum – square-stemmed willowherbEpilobium thermophilum Epilobium × thuringiacum Epilobium tianschanicum Epilobium tibetanum Epilobium tonkinense Epilobium torreyi – Torrey's willowherb, brook spike-primroseEpilobium × treleaseanum Epilobium trichophyllum Epilobium tulinianum Epilobium turkestanicum Epilobium × udicola Epilobium × uechtritzianum Epilobium ulleungensis Epilobium vernicosum Epilobium vernonicum Epilobium verticillatum Epilobium × vicinum Epilobium wallichianum Epilobium × waterfallii Epilobium wattianum Epilobium williamsii Epilobium willisii Epilobium wilsonii Epilobium × winkleri Epilobium × wisconsinense – Wisconsin willowherb
Formerly placed here
Stylidium tenellum (as E. tonkinense)
It is possible to distinguish between leaves of different Epilobium species using high-accuracy FT-IR method based on attenuated total reflection (ATR) without time-consuming preparation.
Footnotes
References
Bleeker, Walter; Schmitz, Ulf & Ristow, Michael (2007): Interspecific hybridisation between alien and native plant species in Germany and its consequences for native biodiversity. Biological Conservation 137 (2): 248-253. (HTML abstract, appendix reserved for subscribers)
Steenkamp, V; Gouws, M.C; Gulumian, M; Elgorashi, E.E. & van Stade, J. (2006): Studies on antibacterial, anti-inflammatory and antioxidant activity of herbal remedies used in the treatment of benign prostatic hyperplasia and prostatitis. Journal of Ethnopharmacology'' 103 (1): 71–75. PDF fulltext
Wagner, W.L. & Hoch, P.C. [2009b]: Evening Primrose Family website – Epilobium. Retrieved 2009-JAN-26.
Onagraceae genera
Taxa named by Carl Linnaeus