Trollius paluster Krause
Caltha palustris, known as marsh-marigold and kingcup, is a perennial herbaceous plant of the family Ranunculaceae, native to marshes, fens, ditches and wet woodland in temperate regions of the Northern Hemisphere.
It becomes most luxuriant in partial shade, but is rare on peat. In the United Kingdom, it is probably one of the most ancient native plants, surviving the glaciations and flourishing after the last retreat of the ice, in a landscape inundated with glacial meltwaters.
Height is up to 80 centimetres (31 in) tall. The leaves are rounded to kidney-shaped, 3–20 centimetres (1.2–7.9 in) across, with a bluntly serrated margin and a thick, waxy texture. Stems are hollow.
The flowers are yellow, 2–5 cm (1–2 in) diameter, with 4-9 (mostly 5) petal-like sepals and many yellow stamens; they appear in early spring to late summer. The flowers are visited by a great variety of insects for pollen and for the nectar secreted from small depressions, one on each side of each carpel.
Caltha palustris is a highly polymorphic species, showing continuous and independent variation in many features. Forms in the UK may be divided into two subspecies: Caltha palustris subsp. palustris, and Caltha palustris subsp. minor.
It is sometimes considered a weed in clay-like garden soils, where every piece of its root will survive and spread. In warm free-draining soils, it simply dies away.
As is the case with many members of the family Ranunculaceae, all parts of the plant are poisonous and can be irritant. Skin rashes and dermatitis have been reported from excessive handling of the plant. It is known to sometimes kill cows and will happily grow in cow manure. 
Other names and etymology
In the UK, Caltha palustris is known by a variety of common names, varying by geographical region. These include marsh marigold and kingcup (the two most frequently used common names), mayflower, May blobs, mollyblobs, pollyblobs, horse blob, water blobs, water bubbles, gollins. Balfae (in Caithness) and the publican. The common name of marigold refers to its use in medieval churches at Easter as a tribute to the Virgin Mary, as in Mary gold.
The specific name palustris, Latin for "of the marsh", indicates its common habitat.
Richard Mabey, in Flora Britannica, describes Caltha palustris thus:
"Marsh-marigolds are in decline as agricultural land continues to be drained, but they are still the most three-dimensional of plants, their fleshy leaves and shiny petals impervious to wind and snow, and standing in sharp relief against the tousled brown of frostbitten grasses. Most of the plant's surviving local names - water-blobs, molly-blobs, water-bubbles - reflect this solidity, especially the splendid, rotund 'the publican' from Lancashire."
In North America Caltha palustris is sometimes known as cowslip. However, cowslip more often refers to Primula veris, the original plant to go by that name. Both are herbaceous plants with yellow flowers, but Primula veris is much smaller.
Caltha palustris is a plant commonly mentioned in literature, including Shakespeare:
- Winking Marybuds begin
- To open their golden eyes (Cymbeline, ii. 3).
Kingcup Cottage by Racey Helps is a children's book which features the plant.
In Latvia Caltha palustris is also known as Gundega which is also used as a girls name which symbolizes fire. The word Gundega is made from 2 words - uguns (fire) and dega (burned). This refers to the burning reaction that some people experience from contact with Caltha sap.
Subdivision, synonymy and culture varieties
Caltha palustris is a very variable species. Since most character states occur in almost any combination, this provides little basis for subdivisions. The following varieties are nevertheless widely recognised. They are listed with their respective synonyms. If an epithet based on the same type specimen is used at different levels, only the use at the highest taxonomic rank is listed, so as C. himalensis is already listed, C. palustris var. himalensis is not.
- Yellow sepals, pollen tricolpate, not rooting at the nodes.
→ C. palustris var. palustris =
- C. palustris forma decumbens, f. erecta, f. gigas, f. plena, f. plurisepala, f. pratensis
- C. palustris subvar. palmata
- C. palustris var. acuteserrata, var. bosnica, var. crenata, var. cuneata, var. dentata, var. ficariaeformis, var. holubyi, var. minima, var. nipponica, var. orbicularis, var. ranunculiflora, var. recurvirostris, var. siberica (Regel, 1861), var. stagnalis, var. umbrosa
- C. palustris ssp. thracica
- C. alpestris, C. alpina, C. asarifolia, C. barthei, C. confinis, C. cornuta, C. elata, C. ficarioides, C. fistulosa, C. grosse-serrata, C. guerrangerii, C. himalensis, C. integerrima, C. intermedia, C. laeta, C. latifolia, C. longirostris, C. major, C. minor, C. orthorhyncha, C. pallidiflora, C. parnassifolia, C. polypetala, C. procumbens, C. pumila, C. pygmea, C. ranunculoides, C. riparia, C. silvestris, C. vulgaris
- Yellow sepals, pollen tricolpate, smaller plants, with few-flowered decumbent stems rooting at the nodes after flowering. Grows at the northern edges of the distribution area of the species and on erosion prone banks.
→ C. palustris var. radicans =
- C. palustris var. aleutensis, var. siberica (Tolmachev, 1955)
- C. arctica, C. cespitosa, C. flabellifolia, C. zetlandica
- Yellow sepals, pollen tricolpate, larger plants, with many-flowered erect stems rooting at the nodes after flowering. Occurs in the Netherlands in a fresh water tidal zone (De Biesbosch).
→ C. palustris var. araneosa (only generally recognised in the Netherlands)
- White sepals, pollen pantoporate or sometimes tricolpate. Between 2200 and 3500 m along rivulets in Afganistan, Pakistan and the western Himalayas from Kashmir to northern India.
→ C. palustris var. alba =
- C. palustris forma alpina, f. sylvatica
- C. alba
- Magenta sepals, pollen tricolpate. Between 4000 and 5000 m in alpine meadows and mossy slopes between shrubs and tall herbs in the eastern Himalayas of Assam and southern Tibet.
→ C. palustris var. purpurea =
- C. rubriflora
The 2006-2007 edition of the Royal Horticultural Society Plant Finder, a British publication which lists over 70,000 plants available in nurseries in the United Kingdom, lists in addition to these varieties the following cultivars: Single flowered: "Marilyn", "Trotter's form", "Yellow Giant". Double flowered: "Flore Pleno" (RHS's Award of Garden Merit), "Multiplex", "Plena", "Semiplena".
The marsh-marigold grows in places with oxygen-rich water near the surface of the soil. It likes richer soils, but dislikes application of fertilizer and avoids high concentrations of phosphate and ammonium, and is also shy of brackish water. It is often associated with seepage that is rich in iron, because iron ions react with phosphate, thus making it unavailable for plants. The resulting insoluble mineral appears as "rusty" flocs on the water soil and the surface of the stems of marsh plants. Around the edge of lakes and and rivers it grows between reeds, and it can be found in black alder coppices and other regularly flooded and always moist forests. When it is present it often visually dominates when it is in bloom. It also used to be common on wet meadows, but due to agricultural rationalization it is now limited to ditches.
It is a component of Purple moor grass and rush pastures - a type of Biodiversity Action Plan habitat in the UK. It occurs on poorly drained neutral and acidic soils of the lowlands and upland fringe.
In western Europe, the marsh-marigold moth Micropterix calthella bites open the anthers of the marsh-marigold and other plants to eat the pollen. The caterpillars that are present in summer and autumn also feed on marsh-marigold, although these are sometimes found on mosses too. Another visitor of Caltha palustris in western Europe is the leaf beetle Prasocuris phellandrii, which is black with four orange stripes and around ½ cm and eats the sepals. Its larvae inhabit the hollow stems of members of the parsley family. In the USA (Illinois) two species of leaf beetle can be found on Caltha: Plateumaris nitida and Hydrothassa vittata. The maggots of some Phytomyza species (Agromyzidae) are miners in Caltha leaves.
In Canada, beetles (Cantharidae, Nitidulidae, Coccinellidae, Chrysomelidae, Cerambycidae), thrips (Thripidae), bugs (Miridae), butterflies (Pieridae), sawflies (Tenthredinidae), bees (Apidae, Halictidae, Andrenidae), ants (Formicidae) and flies (Sepsidae, Sciomyzidae, Ephydridae, Syrphidae, Anthomyiidae, Tachinidae and Muscidae) have been observed to visit the leaves or flowers, many of which were found carrying Caltha pollen.
Early spring greens and buds of Caltha palustris are edible when cooked. Young leaves or buds should be submerged a few times in fresh boiling water until barely tender, cut into bite-sized pieces, lightly salted, and served with melted butter and vinegar. Very young flowerbuds have been prepared like capers and used as a spice.
Caltha contains several active substances of which the most important from a toxicological point of view is protoanemonin. Larger quantities of the plant may cause convulsions, burning of the throat, vomiting, bloody diarrhea, dizziness and fainting. Contact of the skin or mucous membranes with the juices can cause blistering or inflammation, and gastric illness if ingested. Younger parts seem to contain less toxics and heating breaks these substances down. Small amounts of Caltha in hay do not cause problems when fed to husbandry, but larger quantities lead to gastric illness.
- Petra G. Smit (1973). "A Revision of Caltha (Ranunculaceae)". Blumea 21: 119–150. Retrieved 2016-01-05.
- "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-02-25. Retrieved 2014-10-17.
- "Common Poisonous Weeds". Ontario Ministry of Agriculture.
- "cowslip". Merriam-Webster Online Dictionary.
- "RHS Plant Selector - Caltha palustris". Retrieved 20 June 2013.
- E.J. Weeda, R. Westra, C. Westra & T. Westra (1985). Nederlandse Oecologische Flora 1. IVN. pp. 226–229.
- John Hilty. "marsh marigold". illinoiswildflowers. Retrieved 2016-01-29.
- George C. Steyskal. Keys to The Insects of The European Part of The USSR 5. Brill Archives. pp. 494, 500–501. ISBN 9004090266.
- Judd, W.W. (1964). "Insects Associated with Flowering Marsh Marigold, Caltha palustris L., at London, Ontario". The Canadian Entomologist 96: 1472–1476. doi:10.4039/Ent961472-11.
- Peter Zwetko: Die Rostpilze Österreichs. Supplement und Wirt-Parasit-Verzeichnis zur 2. Auflage des Catalogus Florae Austriae, III. Teil, Heft 1, Uredinales. (PDF; 1,8 MB).
- "Caltha palustris". Native Plant Database. Lady Bird Johnson Wildflower Center. Retrieved 2016-01-17.
- Clapham, A. R., Tutin, T. G., and Warburg, E. F., 1962, Flora of the British Isles Cambridge University Press
- Lord, Tony (ed), 2006, RHS Plant Finder 2006-2007 London: RHS/Dorling Kindersley ISBN 1-4053-1455-9
- Mabey, Richard, 1997, Flora Britannica London: Chatto and Windus
- Rose, Francis, 2006, The Wild Flower Key (edition revised and expanded by Clare O'Reilly) London: Frederick Warne ISBN 0-7232-5175-4
- Flora of China: Caltha palustris
- Flora Europaea: Caltha palustris
- Flora of North America: Caltha palustris
- Germplasm Resources Information Network: Caltha palustris
- Pink, A. (2004). Gardening for the Million. Project Gutenberg Literary Archive Foundation.
|Wikimedia Commons has media related to Caltha palustris.|