''Epilobium ciliatum'', known by the common names fringed willowherb, American willowherb, slender willow herb, and northern willow herb is a species of ''

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

'' in the willowherb family

Onagraceae The Onagraceae are a family of flowering plants known as the willowherb family or evening primrose family. They include about 650 species of herbs, shrubs, and trees North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, southern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, and

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

. It is an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

in much of Eurasia and Australia. This

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition o ...

usually occurs in wetlands, but may be found in a great variety of habitats, including disturbed areas and roadsides, at elevations below .

Description

''Epilobium ciliatum'' is a clumping perennial often exceeding in height. It has thickly veined lance-shaped leaves which may be up to 15 centimeters long toward the base of the plant. The foliage, stem, and

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

are covered in bristly hairs and glands. There are four sepals. The regular, trumpet-shaped flowers have four petals which are so deeply notched they look like four pairs. They are white to light purple or pink with dark veining. There are eight stamens and a club-shaped stigma. The fruit is a narrow, hairy, four-chambered capsule up to 10 centimeters in length which may be held on a long stalk. The seeds are downy and can float for long distances with the wind.

Subspecies

Three

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are currently recognized: * ''Epilobium ciliatum'' ssp. ''ciliatum'' * ''Epilobium ciliatum'' ssp. ''glandulosum'' — (Lehm.) Hoch & P.H.Raven * ''Epilobium ciliatum'' ssp. ''watsonii'' — (Barbey) Hoch & P.H.RavenUSDA:''Epilobium ciliatum'' ssp. ''watsonii''
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Taxonomy

''Epilobium ciliatum'' may be a

cryptic species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. The Rocky Mountain Willowherb (''Epilobium saximontanum'') is sometimes included as yet another subspecies. The three currently recognized subspecies may each constitute a distinct species. If so, ''E. ciliatum'' ssp. ''watsonii'' would perhaps use the name ''E. adenocaulon'' and include those populations, while ''E. ciliatum'' ssp. glandulosum'' would perhaps use the name ''E. bergianum'' and include those populations. The others named ''E. ciliatum'' ssp. ''ciliatum'' populations would remain.

Distribution and habitat

''Epilobium ciliatum'' is native to the southern part of Canada and most of the United States of America. It is a plant of moist places, stream-sides, ditches, ponds, gardens, roadsides, recently cleared areas and wasteland.

Invasiveness

It arrived in northern Europe early in the 20th century and spread rapidly, reaching Finland in about 1920. It reached Slovenia by 1993 and

Zagorje Hrvatsko Zagorje (; Croatian Zagorje; ''zagorje'' is Croatian language, Croatian for 'backland' or 'behind the hills') is a cultural region in northern Croatia, traditionally separated from the country's capital Zagreb by the Medvednica mount ...

, Croatia by 2001. In Europe, ''Epilobium ciliatum'' competes with and is often found together with ''

Epilobium roseum ''Epilobium roseum'' is a species of flowering plant belonging to the family Onagraceae The Onagraceae are a family of flowering plants known as the willowherb family or evening primrose family. They include about 650 species of herbs, shrubs, ...

'', which prefers a similar habitat.

References

Bibliography

External links

Jepson Manual Treatment for ''Epilobium ciliatum''CalFlora database — ''Epilobium ciliatum'' (Slender Willow herb)''Epilobium ciliatum'' — Photo gallery
{{Taxonbar, from=Q164151 ciliatum Flora of Northern America Flora of southern South America Flora of temperate Asia Flora of the California desert regions Taxa named by Constantine Samuel Rafinesque Flora without expected TNC conservation status