Common Name: Marsh Marigold

General Information

Caltha palustris is a herbaceous perennial plant producing a cluster of basal leaves and flowering stems 20 - 60cm tall[].
The plant is harvested from the wild for local use as a medicine and sometimes as a food. It is grown as an ornamental in gardens, where it can be used to make a ground cover.
Caltha palustris appears to be widespread and abundant with stable populations throughout most or all of its European range. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

The whole plant, but especially the older portions, contains the toxic glycoside protoanemonin - this is destroyed by heat[]. Symptoms of poisoning include a burning sensation in the throat, vomiting, bloody diarrhoea, dizziness, fainting, and, in large doses, convulsions. However, the toxicity is of a fairly low order and the plant would usually need to be eaten in quantity in order to cause major symptoms[]
The sap can irritate sensitive skin[].

Botanical References

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Range

Widespread in the northern Temperate zone through Europe, northern Asia and N. America

Habitat

Wet areas in marshes, fens, ditches and wet alder woods[, ]. Rare on very base poor peat[]. Marshes, fens, ditches, wet woods and swamps, thriving best in open or only partly shaded sites; at elevations up to 1,500 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	0.30 m
Pollinators	Bees, Beetles, Flies
Cultivation Status	Ornamental, Wild

Cultivation Details

A plant of the waterside, it prefers growing in a sunny position in wet soils or shallow water up to 15cm deep[, , ], though it will tolerate drier conditions if there is shade from the summer sun[]. Another report says that it grows best in partial shade[]. Requires a deep rich slightly alkaline soil[, ]. Grows well in heavy clay soils. Prefers a chalky soil[]. Tolerates a pH in the range 4.8 to 7.5.
A very ornamental[] and polymorphic plant[], there are some named varieties[]. Plants often self-sow when well sited[].
A good bee plant[].
A greedy plant, inhibiting the growth of nearby plants, especially legumes[].
This species is probably the most primitive flower in the British flora[].

Edible Uses

Root - must be well cooked[]. The raw root should not be eaten[]. Some caution is advised, see the notes above on toxicity.

Flower buds - raw, cooked or pickled and used as a caper substitute[, ]. Eating the raw flower buds can lead to intoxication[]. Some caution is advised, see the notes above on toxicity.

Young leaves - raw or cooked[, , , , ]. The leaves are harvested in the spring as the plant is coming into flower and is used like spinach after cooking in two or more changes of water[, ]. Eating the raw leaves can lead to intoxication[]. Some caution is advised, see the notes above on toxicity.
Older leaves, before the plant flowers, can be eaten if they are well cooked[]. Some caution is advised, see the notes above on toxicity.

Medicinal

Every part of this plant is strongly irritant and so it should be used with caution[]. All parts of the plant can irritate or blister the skin or mucous membranes[].

The whole plant is anodyne, antispasmodic, diaphoretic, diuretic, expectorant and rubefacient[, ]. It has been used to remove warts and is also used in the treatment of fits and anaemia[, , ].

The root is antirheumatic, diaphoretic, emetic and expectorant[, ]. A decoction is used in the treatment of colds[].
A poultice of the boiled and mashed roots has been applied to sores[].

A tea made from the leaves is diuretic and laxative[, ].

The plant is used in homoeopathy to treat pain in the abdomen, vomiting, headache, singing in ears, dysuria and diarrhoea[].

Agroforestry Uses:

Plants can be grown for ground cover when planted about 45cm apart each way[].

Other Uses

A yellow dye is obtained from the flowers[[, ], a saffron substitute[]. It is used as a dye when mixed with alum, though it is not very permanent[].

Propagation

Seed - best sown as soon as it is ripe in a cold frame in late summer[]. Stand the pots in 2 - 3cm of water to keep the soil wet. The seed usually germinates in 1 - 3 months at 15°c[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in a tray of water in a cold frame until they are at least 15cm tall. Plant them out into their permanent positions in the summer.
Division in early spring or autumn[]. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the summer or following spring.