Epilobium

Epilobium
Great Willowherb (Epilobium hirsutum)
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Eudicotyledoneae
Subclass:	Rosidae
Order:	Myrtales
Family:	Onagraceae
Genus:	Epilobium L.
Species
160-200, see text
Synonyms
Boisduvalia Chamaenerion Chamerion (but see text) Pyrogennema Zauschneria

Epilobium is a genus in the family Onagraceae, containing about 160-200 species of flowering plants with a worldwide distribution. They are generally abundant in the subarctic, temperate and subantarctic regions, whereas in the subtropics and tropics they are restricted to the cool montane biomes, such as the New Guinea Highlands where they are plentiful.

The taxonomy of the genus has varied between different botanists, but the modern trend is to include the previously recognised genera Boisduvalia, Chamaenerion, Chamerion, Pyrogennema and Zauschneria within Epilobium. Chamerion might be distinct however^[1], as advocated for example by Peter H. Raven who has extensively studied the willowherbs and does on the other hand merge the other segregate genera into Epilobium. Fringed Willowherb (E. ciliatum) is suspected to be a cryptic species complex; apparently these plants also commonly hybridize with their congeners^[2].

Most species are known by the common name willowherbs; in particular those that were once separated in Boisduvalia are called spike-primroses or boisduvalias. Yet other species, namely ones that are placed in the Chamerion group, are also known as "fireweeds".

Description and ecology

Ripe capsule of Zauschneria (E. canum) releasing seed

They are mostly herbaceous plants, either annual or perennial; a few are subshrubs. The leaves are mostly opposite or whorled, alternate in a few species, simple, and ovate to lanceolate in shape. The flowers have four petals. These are usually smallish and pink in most species, but red, orange or yellow in a few, and large and bright magenta in the Chamerion group. 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.

Willowherbs are typically very quick to carpet large swathes of ground and may form key or even dominant species of local ecosystem. In and around the United Kingdom for example, Rosebay Willowherb (E. angustifolium) is widely found in mesotrophic grassland dominated by False Oat-grass (Arrhenatherum elatius), Cock's-foot (Dactylis glomerata) and Red Festuce (Festuca rubra), while Great Willowherb (Epilobium hirsutum) is found in mesotrophic grassland with abundant False Oat-grass, Cock's-foot and Stinging Nettle (Urtica dioica). These two willowherb species are also seen to 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 rich in False Oat-grass, Meadowsweet (Filipendula ulmaria), and sometimes the otherwise rare Greek Valerian (Polemonium caeruleum), which are peculiar to the Pennines. Most willowherbs will not tolerate shade trees well and thus are limited to comparatively freshly disturbed patches, yielding to other plants as the years pass by. 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
• Double-striped Pug (Gymnoscelis rufifasciata), recorded on Fireweed (E. angustifolium)

Noctuidae

• Mouse Moth (Amphipyra tragopoginis), recorded on several species
• Small Angle Shades (Euplexia lucipara), recorded on several species
• The Gothic (Naenia typica), recorded on Fireweed (E. angustifolium)
• Hebrew Character (Orthosia gothica), recorded on Fireweed (E. angustifolium)
• Australian Grapevine Moth (Phalaenoides glycinae), recorded on Fringed Willowherb (E. ciliatum)
• Setaceous Hebrew Character (Xestia c-nigrum), recorded on Fireweed (E. angustifolium)

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

Fireweed (E. angustifolium) growing along rail tracks in Denali National Park, Alaska

Many of the small willowherb species are nuisance weeds in gardens. Though few are regularly used as ornamental plants, most people find the larger willowherbs to give a pleasing aspect to 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. Epilobium angustifolium is the floral emblem of Yukon territory in Canada, Hedmark county in Norway (where the plant is called geitrams) and of the Southern Ostrobothnia region of Finland.

Fireweed is used as a sweetener in northwestern North America; it is put in candies, jellies ice cream, syrup and other treats, as well as in sxusem ("Indian ice-cream"). In the latter months of summer its flowers yield pollen and copious nectar which gives 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 to keep their dogs healthy and credit the sap of the species' stem, applied to wounds, with antiinflammatory properties. Small-flowered Willowherb (E. parviflorum) is held to improve urogenital functions in European folk medicine^{[citation needed]}

Several eminent scientists have done research on these plants: Heinrich Carl Haussknecht in the late 19th century and Peter H. Raven about a century later have researched phylogeny, systematics and taxonomy of willowherbs extensively. Peter Michaelis' studies of this genus paved the way for understanding of extranuclear inheritance in plants.

Species

The National Museum of Natural History recognizes an intermediate number of about 175 species in 10 sections, including two sections of Chamerion which they consider distinct^[1]. Other sources may list one or two dozen species more or less:

Tall Willowherb (Epilobium brachycarpum)

Zauschneria (Epilobium canum)

Section Boisduvalia

• Epilobium densiflorum – Denseflower Willowherb, Dense Spike-primrose, Dense Boisduvalia
• Epilobium pallidum – Largeflower Spike-primrose
• Epilobium pygmaeum^{[verification needed]} – Pygmy Willowherb, Smooth Boisduvalia
• Epilobium subdentatum (Meyen) Lievens & Hoch
• Epilobium torreyi – Torrey's Willowherb, Brook Spike-primrose

Section Cordylophorum

Subsection Nuttalia

• Epilobium suffruticosum Nutt. ex Torr. & A.Gray – Shrubby Willowherb

Subsection Petrolobium

• Epilobium nevadense Munz – Nevada Willowherb
• Epilobium nivium Brandegee – Snow Mountain Willowherb

Section Crossostigma

• Epilobium foliosum – Leafy Willowherb, California Willowherb
• Epilobium minutum – Chaparral Willowherb, Desert Willowherb, "smallflower willowherb"

Section Epilobiopsis

• Epilobium campestre (Jeps.) Hoch & W.L.Wagner
• Epilobium cleistogamum – Selfing Willowherb

Section Macrocarpa

• Epilobium rigidum – Stiff Willowherb, Siskiyou Mountains Willowherb

Section Xerolobium

• Epilobium brachycarpum – Tall Willowherb, Tall Annual Willowherb, Tall Fireweed, Panicled Willowherb

Section Zauschneria

• Epilobium canum – Zauschneria, California-fuchsia, Hummingbird Flower, Hummingbird Trumpet
• Epilobium septentrionale – Northern Willowherb, Humboldt County Fuchsia

Epilobium alpestre

Top left: Chickweed Willowherb (Epilobium alsinifolium)
Bottom left: Alpine Willowherb (Epilobium anagallidifolium)
Center: Square-stemmed Willowherb (Epilobium tetragonum)

Epilobium billardierianum

Left: Pale Willowherb (Epilobium roseum)
Right: Dwarf Willowherb (Epilobium obscurum)

Small-flowered Willowherb (Epilobium parviflorum)

Section Epilobium

• Epilobium aitchisonii P.H.Raven
• Epilobium algidum M.Bieb.
• Epilobium alpestre (Jacq.) Krock.
• Epilobium alsinifolium Vill. – Chickweed Willowherb
• Epilobium alsinoides A.Cunn.
  • Epilobium alsinoides ssp. alsinoides
  • Epilobium alsinoides ssp. atriplicifolium (A.Cunn.) P.H.Raven & Engelhorn
  • Epilobium alsinoides ssp. tenuipes (Hook.f.) P.H. Raven & Engelhorn
• Epilobium amurense Hausskn.
  • Epilobium amurense ssp. amurense
  • Epilobium amurense ssp. cephalostigma (Hausskn.) C.J.Chen, Hoch & P.H.Raven
• Epilobium anagallidifolium – Alpine Willowherb, Pimpernel Willowherb
• Epilobium anatolicum Hausskn.
  • Epilobium anatolicum ssp. anatolicum
  • Epilobium anatolicum ssp. prionophyllum (Hausskn.) P.H.Raven
• Epilobium angustum (Cheeseman) P.H. Raven & Engelhorn
• Epilobium arcticum Sam. – Arctic Willowherb (sometimes included in E. davuricum^{[verification needed]})
• Epilobium astonii (Allan) P.H.Raven & Engelhorn
• Epilobium atlanticum Litard. & Maire
• Epilobium australe Poeppig & Hausskn.
• Epilobium barbeyanum H.Lév.
• Epilobium billardierianum Ser. – Glabrous Willowherb
  • Epilobium billardierianum ssp. billardierianum
  • Epilobium billardierianum ssp. cinereum (A.Rich.) P.H.Raven & Engelhorn
  • Epilobium billardierianum ssp. hydrophilum P.H. Raven & Engelhorn
  • Epilobium billardierianum ssp. intermedium P.H. Raven & Engelhorn
• Epilobium blinii H.Lév.
• Epilobium brevifolium D.Don
  • Epilobium brevifolium ssp. brevifolium
  • Epilobium brevifolium ssp. trichoneurum (Hausskn.) P.H.Raven
• Epilobium brevipes Hook.f.
• Epilobium brevisquamatum P.H.Raven
• Epilobium brunnescens (Cockayne) P.H. Raven & Engelhorn – New Zealand Willowherb
  • Epilobium brunnescens ssp. beaugleholei K.R.West & P.H.Raven
  • Epilobium brunnescens ssp. brunnescens
  • Epilobium brunnescens ssp. minutiflorum (Cockayne) P.H. Raven & Engelhorn
• Epilobium capense Buchinger ex Hochst.
• Epilobium chionanthum Hausskn.
• Epilobium chitralense P.H.Raven
• Epilobium chlorifolium Hausskn.
• Epilobium ciliatum – Fringed Willowherb, American Willowherb
• Epilobium clarkeanum Hausskn.
• Epilobium clavatum – Talus Willowherb, Clavatefruit Willowherb
• Epilobium collinum C.C.Gmelin
• Epilobium coloratum Biehler – Purpleleaf Willowherb
• Epilobium confertifolium Hook.f.
• Epilobium confusum Hausskn.
• Epilobium conjungens Skottsb.
• Epilobium crassum Hook.f.
• Epilobium curtisiae P.H.Raven
• Epilobium cylindricum D.Don
• Epilobium davuricum Fisch. ex Hornem. – Daurian Willowherb
• Epilobium densifolium Hausskn.
• Epilobium denticulatum Ruiz & Pav.
• Epilobium detzneranum Schltr. ex Diels
• Epilobium duriaei Gay ex Godr.
• Epilobium fangii C.J.Chen, Hoch & P.H.Raven
• Epilobium fastigiatoramosum Nakai
• Epilobium fauriei H.Lév.
• Epilobium forbesii Allan
• Epilobium fragile Sam.
• Epilobium frigidum Hausskn.
• Epilobium fugitivum P.H. Raven & Engelhorn
• Epilobium gemmascens C.A.Mey.
• Epilobium glabellum G.Forst. – Smooth Spike-primrose
• Epilobium glaberrimum – Glaucous Willowherb
• Epilobium glaciale P.H.Raven
• Epilobium glaucum Phil.
• Epilobium gouldii P.H.Raven
• Epilobium gracilipes Kirk
• Epilobium griffithianum Hausskn.
• Epilobium gunnianum Hausskn.
• Epilobium halleanum – Glandular Willowherb
• Epilobium hectorii Hausskn.
• Epilobium hirsutum – Great Willowherb, Great Hairy Willowherb, Hairy Willowherb, Codlins-and-cream, Apple-pie, "cherry-pie"
• Epilobium hirtigerum A.Cunn.
• Epilobium hohuanense S.S.Ying
• Epilobium hooglandii P.H.Raven
• Epilobium hornemannii Rchb. – Hornemann's Willowherb
  • Epilobium hornemannii ssp. behringianum (Hausskn.) Hoch & P.H.Raven
  • Epilobium hornemannii ssp. hornemannii
• Epilobium howellii – Yuba Pass Willowherb, Subalpine Fireweed
• Epilobium indicum Hausskn.
• Epilobium insulare Hausskn.
• Epilobium kermodei P.H.Raven
• Epilobium keysseri Diels
• Epilobium kingdonii P.H.Raven
• Epilobium komarovianum H.Lév. – Bronzy Willowherb
• Epilobium lactiflorum – Milkflower Willowherb, Whiteflower Willowherb
• Epilobium lanceolatum Sebast. & Mauri – Spear-leaved Willowherb
• Epilobium laxum Royle
• Epilobium leiophyllum Hausskn.
• Epilobium leptocarpum Hausskn. – Slenderfruit Willowherb
• Epilobium leptophyllum – Bog Willowherb, Linear-leaved Willowherb
• Epilobium luteum Pursh – Yellow Willowherb
• Epilobium macropus Hook.
• Epilobium margaretiae Brockie
• Epilobium matthewsii Petrie
• Epilobium maysillesii Munz
• Epilobium melanocaulon Hook.
• Epilobium microphyllum A.Rich.
• Epilobium minutiflorum Hausskn.
• Epilobium mirabile Trel. – Olympic Mountain Willowherb
• Epilobium montanum – Broad-leaved Willowherb
• Epilobium nankotaizanense Yamam. – Nankotaizan Willowherb
• Epilobium nerteroides A.Cunn.
• Epilobium nivale Meyen
• Epilobium nummulariifolium R.Cunn. ex A.Cunn.
• Epilobium nutans F.W.Schmidt
• Epilobium obcordatum – Rockfringe Willowherb
• Epilobium obscurum Schreb. – Dwarf Willowherb, Short-fruited Willowherb
• Epilobium oreganum – Grants Pass Willowherb, Oregon Fireweed
• Epilobium oregonense – Oregon Willowherb
• Epilobium pallidiflorum Sol. ex A.Cunn.
• Epilobium palustre – Marsh Willowherb
• Epilobium pannosum Hausskn.
• Epilobium parviflorum Schreb. – Small-flowered Willowherb, Hoary Willowherb
• Epilobium pedicellare C.Presl
• Epilobium pedunculare A.Cunn. – Rockery Willowherb
• Epilobium pengii C.J.Chen, Hoch & P.H.Raven
• Epilobium pernitens Cockayne & Allan
• Epilobium perpusillum Hausskn.
• Epilobium petraeum Heenan
• Epilobium pictum Petrie
• Epilobium platystigmatosum C.B.Rob.
• Epilobium ponticum Hausskn.
• Epilobium porphyrium G.Simpson
• Epilobium prostratum Warb.
• Epilobium psilotum Maire & Sam.
• Epilobium pubens A.Rich.
• Epilobium puberulum Hook. & Arn.
• Epilobium purpuratum Hook.f.
• Epilobium pycnostachyum Hausskn.
• Epilobium pyrricholophum Franch. & Sav.
• Epilobium rechingeri P.H.Raven
• Epilobium rhynchospermum Boiss.
• Epilobium roseum Schreb. – Pale Willowherb
  • Epilobium roseum ssp. consimile (Hausskn.) P.H.Raven
  • Epilobium roseum ssp. roseum
  • Epilobium roseum ssp. subsessile (Boiss.) P.H.Raven
• Epilobium rostratum Cheeseman
• Epilobium rotundifolium G.Forst.
• Epilobium royleanum Hausskn.
• Epilobium rupicolum Pavlov
• Epilobium salignum Hausskn.
• Epilobium sarmentaceum Hausskn.
• Epilobium saximontanum Hausskn. – Rocky Mountain Willowherb
• Epilobium sikkimense Hausskn.
• Epilobium sinense H.Lév.
• Epilobium siskiyouense – Siskiyou Willowherb, Siskiyou Fireweed
• Epilobium smithii H.Lév.
• Epilobium staintonii P.H.Raven
• Epilobium stereophyllum Fresen.
• Epilobium stracheyanum Hausskn.
• Epilobium strictum Muhl. – Downy Willowherb, Stiff Spike-primrose
• Epilobium subalgidum Hausskn.
• Epilobium subcoriaceum Hausskn.
• Epilobium subnivale Popov ex Pavlov
• Epilobium taiwanianum C.J.Chen, Hoch & P.H.Raven
• Epilobium tasmanicum Hausskn.
• Epilobium tetragonum L. – Square-stemmed Willowherb
  • Epilobium tetragonum ssp. lamyi (F.W.Schultz) Nyman
  • Epilobium tetragonum ssp. tetragonum
  • Epilobium tetragonum ssp. tournefortii (Michalet) H.Lév.
• Epilobium tianschanicum Pavlov
• Epilobium tibetanum Hausskn.
• Epilobium trichophyllum Hausskn.
• Epilobium vernonicum Snogerup
• Epilobium wallichianum Hausskn.
• Epilobium warakense Nábelek
• Epilobium wattianum Hausskn.
• Epilobium williamsii P.H.Raven
• Epilobium willisii P.H. Raven & Engelhorn
• Epilobium wilsonii Cheeseman
• Epilobium × wisconsinense Ugent – Wisconsin Willowherb (= E. ciliatum ssp. ciliatum × E. coloratum)

Chamerion fleischeri/Epilobium fleischeri

Chamerion group

Section Chamerion

• Epilobium angustifolium – Fireweed, Rosebay Willowherb; yanagiran (Japanese)
• Epilobium conspersum
• Epilobium latifolium – Dwarf Fireweed, River Beauty Willowherb
• Epilobium speciosum

Section Rosmarinifolium

• Epilobium colchicum
• Epilobium dodonaei
• Epilobium fleischeri
• Epilobium stevenii

Formerly placed here

• Escallonia pulverulenta^{[verification needed]}
• Stylidium tenellum (as E. tonkinense)

Footnotes

1. ^ ^{a b} Wagner & Hoch [2009a,b]
2. ^ Bleeker et al. (2007)

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. doi:10.1016/j.biocon.2007.02.004 (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. doi:10.1016/j.jep.2005.07.007 PDF fulltext
• Wagner, W.L. & Hoch, P.C. [2009a]: Evening Primrose Family website – Chamerion. Retrieved 2009-JAN-26.
• Wagner, W.L. & Hoch, P.C. [2009b]: Evening Primrose Family website – Epilobium. Retrieved 2009-JAN-26.