- Latin synonym: Ranunculus ficaria
- Name also: Pilewort, Fig Buttercup (USA)
- Family: Buttercup Family – Ranunculaceae
- Growing form: Perennial herb. Part of the root with club-like swellings.
- Height: 10–30 cm (4–12 in.). Stem erect (sometimes ascending), branched, glabrous.
- Flower: Corolla regular (actinomorphic), yellow, 20–30 mm (0.8–1.2 in.) wide; petals 7–12, linearly lanceolate, longer than sepals. Sepals 3, yellowish. Receptacle glabrous. Stamens many. Gynoecium separate, with many pistils. Flowers solitary in axils, quite long-stalked.
- Leaves: Alternate, long-stalked. Blade widely ovate–triangular, glabrous, shiny, cordate-based, with winding margins. Axillary usually round bulbils.
- Fruit: Hairy, approx. 2.5 mm (0.1) long achene, tip with short bristle. Achenes often undeveloped.
- Habitat: Stream banks, seaside broad-leaved forests, waterside meadows, hedgerows, coppices, parks, yards. Also ornamental and an escape from cultivation.
- Flowering time: (April–)May(–June).
Lesser celandine is a spring flower which shines in broad-leaved forests and on river banks – until midsummer it is lost, apart from the last remaining white, withered leaves. Lesser celandine spends most of the year underground as a swollen, club-like root, as described by its scientific name ficaria, ’fig-like’. The species propagates itself by means of its tubers and also via the pale bulbils that grow in the axils of the lowers stem leaves and are carried off by autumn floods. Both methods are efficient: lesser celandine’s golden yellow stands can brighten up river banks for hundreds of metres. These stands are often one and the same clone, i.e. they have the same genotype. Finnish lesser celandine has basically lost its ability to propagate sexually by seed, even though the flower has nectar and insects pollinate it regularly. When the achenes manage to develop they have a poor ability to germinate.
Its splendid inflorescence is not just a burden for the species: it is attractive to the human eye and clergymen, farmers and the gentry have planted it in their yards to such an extent that it became a symbol of the better-off classes. Plants that were introduced to flowerbeds to provide some colour in the spring have spread to lawns and park-like nearby forests, where they would not have reached without human help.
Lesser celandine’s young, nutty-flavoured leaves have been used in salads. The tubers are also known to have been roasted for food as far back as the Bronze Age. It has been locally known as peanut, although the name is now currently reserved for the South American pea plant, which is in actual fact a legume! According to contemporary research, lesser celandine’s tubers are slightly poisonous. It is therefore safest to leave them uneaten and satisfy one’s passion for peanuts with the familiar South American variety.