(Hornemann's willowherb)
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Photo of Epilobium hornemannii by Carl Roland
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Epilobium hornemannii is a perennial herb in the evening primrose family (Onagraceae) found in floodplains, rocky slopes, lush meadows and moist tundra. It has a loosely clumped habit, and grows from leafy
stolons, up to 35 cm tall. The
simple leaves are sparsely denticulate, up to 6 cm long, 3 cm wide, and
lanceolate,
elliptic or
ovate (the upper leaves are usually narrower). Stem leaves are alternate on an unbranched stem. The
inflorescence is a
glandular terminal
raceme either nodding or erect in flower. Flowers are
perfect; the petals are rose to pink, up to 11 mm long. The fruit is an elongated
dehiscent capsule, 3-5 cm long. Seeds have a tuft of silky white hair to aid in wind dissemination. In Denali, this species is most similar to
E. anagallidifolium, but that species is lower growing and matted, and has
glabrous inflorescences,
entire leaves and a smaller stature.
This species flowers in mid-summer.
Plants are
monoecious, with bisexual flowers. Flowers are likely insect pollinated. Seeds have a long tuft of white hairs, to aid wind dispersal.
Epilobium hornemannii is a circumpolar species (with gaps). In North America, this species occurs across the continent, except for dry lowlands in the central Canadian Provinces and U.S. States. This species occurs in Alaska, British Columbia, Yukon Territory, Northwest Territories, and Newfoundland, south to Maine on the east coast and to New Mexico in the west. In Alaska, E. hornemannii occurs mostly south of the 65th parallel. In Denali, it is uncommon north of the Alaska Range crest but common on the southern slopes of the range, particularly in mountain meadows.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Throughout most of the range of Epilobium hornemannii it is a subalpine to alpine species. It is documented in Alaska from sea level to 1500 m. In Denali it occurs at 201-1472 m, and at an average of 915 m. Most occurrences are at 800-1100 m for both north and south-facing slopes, the upper range of altitude and occurrences is on south-facing slopes. Inclines range from 0-39 degrees, average 17 degrees, with the majority of occurrences between 10-30 degrees on both north and south-facing slopes.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Moist sites.
