Common Name: Water Arum

General Information

Calla palustris is a herbaceous perennial plant growing from a flattish, green rhizome. Heart-shaped leaves up to 10cm wide, on stems up to 20cm long, are produced at intervals along the rhizome; the plant grows up to 25cm tall[].
The plant is harvested from the wild for local use as a food and a medicine. It is often grown as an ornamental in gardens.
This species is widespread and abundant throughout its known range and populations are generally stable, though there is evidence of a decline in Switzerland, Croatia and France.The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

The plant contains calcium oxylate crystals[]. These cause an extremely unpleasant sensation similar to needles being stuck into the mouth and tongue if they are eaten, but they are easily neutralized by thoroughly drying or cooking the plant or by steeping it in water[].

Botanical References

,

Range

Eurasia - Norway to France, east to the Russian Far East, Japan, Korea, China, Turkey; N. America - Alaska to Newfoundland, south to West Virginia

Habitat

Forest swamps, moorland marshes, by ponds and streams[]. Found in a wide variety of water bodies, including ponds, lakes and marshes; usually on peat and often associated with woodland[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Habit	Perennial
Height	0.25 m
Pollinators	Flies
Cultivation Status	Wild

Cultivation Details

Requires a wet lime-free humus rich soil by water or in shallow, still or slowly flowing water in full sun[]. When grown on the pond margins it creeps in and out of the water[]. Succeeds in water up to 25cm deep[].

Edible Uses

Rhizome - cooked. It is usually prepared by drying the root, grinding it into a powder and then thoroughly cooking it to ensure that any acrimonious principle is completely destroyed. The resulting powder is rich in starch and can be used as a flour for making bread etc, especially in conjunction with cereal flours[, , , , ]. It is said to be very tasty[].

Fruit (does this include the seed?) - it should be dried and then thoroughly cooked[]. The dried fruit and rootstalk can be ground into an unpalatable but nutritious powder[]. The seed is dried, cooked and ground into a powder[].

Medicinal

Antirheumatic. Used in the treatment of colds and flu[].

A tea made from the dried root has been used in the treatment of flu, shortness of breath, bleeding and as a poultice on swellings and snakebites[, ].

The aerial stems have been used in the treatment of sore legs[].

Other Uses

None known

Propagation

Seed - best sown as soon as it is ripe in late summer in a cold frame in pots standing in about 3cm of water[]. Sow stored seed as early as possible in the year in a greenhouse. The germination rate of stored seed is often poor. When large enough to handle, prick the seedlings out into individual pots and grow them on in trays of water in the greenhouse for at least their first winter, planting them out into their permanent positions in late spring or early summer, after the last expected frosts.
Division in spring[]. Very easy, it is possible to divide this plant at almost any time in the growing season. Any part of the stem, if placed in water or a pot of very wet soil, will quickly root away to form a new plant.
Stem cuttings in summer, rooted in wet mud[].