- Name also: Nodding Avens, Drooping Avens, Purple Avens, Cure All, Water Flower
- Family: Rose Family – Rosaceae
- Growing form: Perennial herb. Rootstock vertical, clove-like fragrance.
- Height: 25–50 cm (10–20 in.). Stem soft-haired, upper part reddish brown.
- Flower: Corolla campanulate, yellowish white–reddish, dark-veined, 10–15 mm (0.4–0.6 in.) broad; petals usually 5, slightly longer than calyx. Calyx quite campanulate, 5-lobed, reddish brown; with epicalyx. Stamens many. Gynoecium separate, pistils several. Inflorescence a sparse corymb, flowers nodding.
- Leaves: In basal rosette and alternate on stem, stalked, stipulate. Rosette leaves’ blade pinnate, 2–4-paired, with terminal leaflet. Terminal leaflet 3-lobed, lobes large-toothed–shallowly lobed. Stem leaves’ blade deeply 3-lobed. Stipules small.
- Fruit: Achene with hooked hairs, several together. Infructescence spherical, erect.
- Habitat: Meadows, banks, ditches, broad-leaved forests, springs, stream banks, rich swamps, fens.
- Flowering time: May–July.
Water avens’s large, nodding, reddish brown flowers make it an impressive sight and an easily recognizable plant. Its large number of local Finnish names show how it has been known to Finns for a long time. The honey bees and bumblebees that are always buzzing around the plant usually led people to name the plant after these insects – or wasps, which do not however pollinate the plant.
Water avens is a native plant that grows almost all over Finland, with the exception of fell Lapland. It is only common in the southern half of the country, however, from the tip of the Bay of Bothnia to the south. In the wild water avens thrives in different kinds of damp and rich places: shore-side hedgerows, stream banks, springs and especially in rich swamps in northern parts of its habitat. It also spreads willingly to artificially created environments and thrives along ditch banks. The way that it accompanies people around can also be partly explained by the way that the hooked tips and stiff hairs of its achenes help it easily attach to passing people and animals.
Water avens’ stamens and pistils develop at different times, which prevents self-pollination. It can however cross-breed with herb Bennet (G. urbanum). People affecting the environment and efficiently spreading plants have increased its possibilities of cross-breeding. The hybrid (G. rivale x urbanum) usually has yellow flowers which look more like water avens’. They can apparently cross-breed again with water avens, and later generations come to resemble it more and more.