Epilobium ciliatum (Fringed Willowherb)

Plant Info
Also known as: American Willowherb, Northern Willowherb, Common Willowherb
Genus:Epilobium
Family:Onagraceae (Evening Primrose)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; average to wet; meadows, shores, river banks, floodplains, marshes, swamps, bogs, forest edges, cliffs, rock outcrops
Bloom season:June - October
Plant height:12 to 40 inches
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 4-petals

[photo of flowers] Flowers are single at the top of the stem and arising from leaf axils in the upper half of the plant. Flowers are white to pink to rose-purple, ¼ to 1/3 inch across with 4 notched petals. In the center is a white club-shaped style surrounded by 8 stamens of varying lengths.

[photo of sepals, ovaries and buds] The 4 sepals cupping the flower are narrowly oblong-elliptic and shorter than the petals; in bud, the sepal tips are not very distinct and the bud is more or less rounded at the tip. Flower stalks are short, less than ½ inch long. Between the flower and stalk is a slender ovary about an inch long and slightly wider than the stalk. The sepals, stalk and ovary are all variously covered in short straight and/or curved hairs mixed with gland-tipped hairs; hairs are sometimes in lines.

Leaves and stems: Leaf attachment: alternate Leaf attachment: opposite Leaf type: simple

[photo of leaves] Leaves are mostly opposite though usually alternate on the upper stem, egg-shaped to lance-elliptic, 1 to 3 inches long, up to about 1 inch wide, blunt to pointed at the tip, short-stalked to stalkless, and somewhat shiny especially when young. Edges are minutely toothed, the teeth usually well-separated and little more than tiny glands, the space between them (sinus) flattish to slightly concave.

[photo of hairs and glands on the upper stem] Leaves on the lower plant are hairless, those nearer the flowers are commonly sparsely covered in short, straight and/or curved hairs mixed with glandular hairs, especially along the midvein. Stems are usually single, branched in the upper plant, green, hairless on the lower stem, the upper stem covered in short straight and/or curved hairs mixed with glandular hairs, often in lines running down from the leaf stalk (decurrent). Vegetative buds (turions) are sometimes produced.

Fruit: Fruit type: capsule/pod Fruit type: seed with plume

[photo of fruit] The ovary elongates up to about 4 inches as it matures, drying to brown then splitting lengthwise from the top down in 2 to 4 segments, the sides curving away and releasing the numerous seeds. Seeds are somewhat cone-shaped, brown, up to about 1.5 mm long, the surface grooved in lines (striate); at the tip is a tuft of long, white hairs to carry it off in the wind.

Notes:

Fringed Willowherb is one of the most common Willowherbs in Minnesota, found in all manner of wet places across the state, though sometimes found in drier sites such as cliff ledges. The Minnesota Willowherbs can be split into 2 groups, based on whether leaves are toothed or not. The toothed group includes natives Fringed Willowherb (E. ciliatum) and Purple-leaf Willowherb (E. coloratum). A third species, the non-native Great Hairy Willowherb (E. hirsutum) is not known to be in Minnesota but is present in Wisconsin and may eventually naturalize here; it has much larger, purplish pink flowers with a 4-parted style and leaves are all stalkless and mostly clasping.

Distinguishing the two natives can be something of a challenge. The most distinct characteristic between E. ciliatum and E. coloratum is the color of the hairs on mature fruit: E. ciliatum is white and E. coloratum is cinnamon-colored, though is quite pale when immature. There are 2 subspecies of E. ciliatum in Minnesota: subsp. glandulosum (formerly E. glandulosum) produces turions late in the season, is unbranched or few branched in the upper plant, and flowers are pink to rose purple; subsp. ciliatum forms a basal rosette of leaves but no turions, is more heavily branched and flowers are white to pink.

If mature fruit or hairs are not available some combination of more subtle characteristics may lead to a positive ID for either E. ciliatum or E. coloratum:

  • E. ciliatum tends to be less bushy than E. coloratum.
  • E. ciliatum leaves are commonly more egg-shaped with a blunt tip and are somewhat shiny, especially when young, where E. coloratum leaves are commonly more narrowly lance-oblong with a pointed tip, often with a long taper to the tip, and have a dull surface.
  • The teeth on E. ciliatum leaves are little more than tiny glands, tend to be widely spaced (but not always), and the sinus between teeth is flattish to slightly concave, where E. coloratum teeth are more irregular, usually closer together and the sinus deeper and usually well-rounded (but not always).
  • E. ciliatum midstem leaves are stalkless or minutely stalked, those of E. coloratum are usually all distinctly short-stalked.
  • E. ciliatum flower buds are usually rounded at the tip, the sepal tips not dramatically distinct, where E. coloratum sepal tips are pretty distinct, and may even flare out a bit.
  • E. ciliatum tends to bloom 2 to 4 weeks earlier than E. coloratum; we noted E. ciliatum blooming in late June and E. coloratum in mid to late July. Both may bloom through September.
  • The hairs on E. ciliatum tend to be a mix of straight and curved hairs where E. coloratum hairs are mostly curved; glandular hairs are more numerous on E. ciliatum than E. coloratum, especially on sepals and ovaries.
  • E. ciliatum seeds are minutely grooved in lines and have a short neck (beak) between the tip of the seed and the hairs, where E. coloratum seeds are covered in tiny bumps (papillose) and have no beak.
  • E. ciliatum may produce vegetative buds (turions) where E. coloratum does not.
  • Some references note that the leaf veins of one of these are quite conspicuous and the other not so much, but there are conflicting reports and we have not found this to be a reliable distinction. The main lateral veins can be prominent on both.

Most of these traits are variable and differences can sometimes be very subtle, so when in doubt inspect multiple specimens to get a consensus. A hand lens can be very helpful.

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More photos

Photos by K. Chayka taken in Carlton and Hubbard counties. Photos by Peter M. Dziuk taken in Anoka, Cook and Ramsey counties, and in Wisconsin.

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