This site and its content are under development.

Ranunculus flammula L., Lesser Spearwort

Account Summary

Native, common, very widespread and locally abundant. European temperate, introduced in a few stations in W Asia and N America.

1881; Stewart, S.A.; Co Fermanagh.

Throughout the year.

Growth form and preferred habitats

This is a very variable, abundant and widespread perennial of soft, wet, marshy ground found mainly around lakes and ponds and in seasonally flooded water-meadows. R. flammula is the type of plant described in Raunkiaer's Life Form Classification as a 'helophyte', a term derived from Greek literally meaning 'a marsh plant'. The term refers to a perennial with an underground storage organ which grows in soil saturated with water and which, therefore, has submerged winter buds and is thus typically shallow rooted like R. flammula (Raunkiaer 1934; Holmes 1979; Grime et al. 1988).

R. flammula occurs in situations where the dense shading effect of tall fen vegetation is excluded or kept minimal by a range of ecological factors, perhaps including nutrient limitation, but more typically involving a combination of seasonal flooding and occasional spates, plus grazing, trampling, cutting or other forms of disturbance, including that generated by popular water-based human leisure activities. It is also very frequent or almost constant in hollows in damp grassland, by flowing water in streams, ditches, springs and in flushes on moors, bogs and upland woods, eg in Fermanagh's wooded Correl Glen NR.

In Britain, R. flammula is mainly associated with moderately oligotrophic to mesotrophic waters (Preston & Croft 1997), but in Fermanagh it also features around or near some of our more decidedly eutrophic waterbodies and it is particularly frequent around Upper Lough Erne. In coastal regions of Britain and Ireland, R. flammula additionally occurs in dune slacks and on damp sea cliffs (Grime et al. 1988).

Under terrestrial habitat conditions R. flammula typically grows erect, but it can also sprawl horizontally to some extent (ie it can be decumbent). However, when the base of the plant becomes submerged in water the habit often becomes creeping. Under these circumstances, it then roots at the nodes, ie it becomes stoloniferous, and given relatively open substrate conditions to colonise, such as bare mud or disturbed soil it may branch and spread to form a clonal patch (Cook & Johnson 1968; Grime et al. 1988). As with other waterside species, this feature undoubtedly plays an important part in the reproduction of R. flammula, since detached portions disperse readily in flowing water.

Preferred soil types

In terms of substrate, Lesser Spearwort generally occurs on wet, moderately acidic, peaty mud, stony gravel or mineral soils, but in Fermanagh it is also very common in limestone and marl situations, eg around Lower Lough Erne and along the pools in the River Finn. This range departs from the British Isles norm to some extent, since Hill et al. (1999) gave it an indicator value for soil reaction of '5', meaning, "of moderately acid soils, only occasionally found on very acid or on neutral to basic soils". The original soil reaction value associated with the species by Ellenberg (1988), based on his experience in continental Europe, was '3', which is significantly (or strongly) inclined towards the acid end of the nine-point scale used in his soil classification. In the Sheffield region of England, Grime et al. (1988) found R. flammula occurred, "mainly on mildly acidic soils between pH 4.5 and 6.5, but extending locally to soils of pH up to 7.5". The latter represents a similar range to that noticed in Fermanagh. In contrast to our local experience, however, they went on to comment, "Rare on calcareous soils." Perhaps the interesting thing is that the species DID also occur on highly calcareous soils, as it very definitely does to a greater extent in Fermanagh. Further north in Scandinavia, R. flammula is regarded as indifferent to lime (Jonsell et al. 2001).

Fermanagh occurrence

Lesser Spearwort is very widespread and abundant in Fermanagh and has been recorded in 438 tetrads, 83% of those in the VC, a situation very much expected in an area of the country with so many lakes and a large expanse of marshy ground, fens, bogs and ditches. Although obviously very widespread throughout the county, it is especially frequent in the area lying south of Lough Erne.

British and Irish occurrence

R. flammula is also frequent and widespread throughout the whole of the British Isles, but has declined to some extent in SE England, presumably due to the usual factors of pressure for land, development, drainage and intensive agriculture (R.A. Fitzgerald, in: Preston et al. 2002).

Is R. flammula really an aquatic plant?

The definition of what constitutes an aquatic plant is not an easy matter to decide, since the boundary between land and water fluctuates over several time scales. Lesser Spearwort is not really a true 'aquatic species' in the ecological sense that fits all the related Water Crowfoots, including the Ranunculus subgenus Batrachium species with the exception of R. hederaceus (Ivy-leaved Crowfoot) and R. omiophyllus (Round-leaved Crowfoot), ie which in Professor Cook's view is limited to "species with a submerged phase during their generative history" (Cook 1966). This very strong delimitation of an aquatic plant makes the submerged phase absolutely obligatory. However, like the two previously mentioned water-crowfoot species, R. flammula is primarily a terrestrial wetland species that very commonly is found standing emergent in water. It may be temporarily submerged, either regularly, or only occasionally whenever local water table levels are higher than normal. It is NOT quite patently a species that, "characteristically grows in water which persists throughout the year", which is the definition of an 'aquatic plant' provided by Preston & Croft (1997). Despite the failure of R. flammula to comply with their definition, the latter authors included a species account of it in their excellent book, Aquatic plants in Britain and Ireland. At the same time Preston & Croft (1997) omitted other native species characteristic of tall-herb fen, which in Fermanagh, and other parts of Ireland, are capable of forming partially emergent floating mats in lakes and rivers. Many of these ignored or neglected species appear equally deserving of treatment as emergent aquatics, eg Cicuta virosa (Cowbane) and Sium latifolium (Great Water-parsnip) (Cook 1998). As with all published selections of plant species, considerations of time, space and cost undoubtedly intrude and they can determine the resulting quorum.

Variation

Living in a fluctuating environment on or near the boundary between land and water, R. flammula shows a high degree of phenotypic variation in form with respect to changes in its environments (ie morphological plasticity). This affects a wide range of characters including size, habit, leaf shape, flower size and even achene shape (Jonsell et al. 2001). Leaf development is particularly variable and plastic in form, to the extent that when the leaf develops under aerial conditions it is lanceolate, whereas when it develops under water, it is linear. This is also a case where heterophylly is of a reversible kind, for although change in shape of an individual leaf is impossible, an extending shoot can produce first one leaf form and then the other, in response to changing environmental growing conditions. It is important to distinguish this kind of heterophylly from that more often met, which is associated with maturation of the plant or entering a flowering phase, where the change in leaf form follows an irreversible one way sequence from youth to maturity (Cook & Johnson 1968).

Three subspecies of R. flammula are recognised by Stace (New Flora of the British Isles, 1997), of which subsp. flammula is the common and widespread form, while the other two, subsp. minimus (A. Benn.) Padmore and subsp. scoticus (E.S. Marshall) A.R. Clapham, are very much more rare or under-recorded. We have not attempted to distinguish the subspecies in Fermanagh, although a few old records of subsp. scoticus exist in the Fermanagh Flora Database (see separate account below).

Possible identification problems

Large specimens of R. flammula, sometimes distinguished as var. ovatus Pers. (= var. major Schult.), can easily enough be mistaken for R. lingua (Greater Spearwort) (Padmore 1957; Preston & Croft 1997). However, in Fermanagh the latter species is almost invariably found growing around Upper Lough Erne and it generally occurs within the taller lakeshore vegetation that R. flammula eschews. Despite the above mentioned phenotypic variation that occurs in R. flammula, after considerable field experience, we find that the small lanceolate leaves of non-flowering specimens are quite distinctive and recognisable.

The more procumbent phenotypes of R. flammula are also sometimes confused with its very rare relative R. reptans (Creeping Buttercup), which is confined to two sites in Scotland and a few, perhaps transient sites in Cumbria (Padmore 1957; Gibbs & Gornall 1976). An equally rare hybrid also occurs between these two species (Gornall 1987; R.A. Fitzgerald & C.D. Preston, in: Preston et al. 2002). The hybrid, R. × levenensis (R. flammula × R. reptans), has been twice recorded in Northern Ireland, from Lough Fea in Co Londonderry (VC H40), near Lough Neagh, which happens to be a major arrival site for waterfowl, which are presumed to transport R. reptans (Gornall 1987).

Flowering

R. flammula flowers abundantly from June to August. It attracts insect visitors and being largely (but not absolutely) self-incompatible, it mainly carries out cross-pollination (Cook & Johnson 1968; Gibbs & Gornall 1976). The flowers are described by Jonsell et al. (2001) as, "weakly protandrous" (ie the pollen matures first) and these Nordic authors also report that selfing is possible when pollination is carried out by raindrops falling into the flower bowl.

Seed production, germination and dormant survival

Published estimates of viable seed production by R. flammula are unknown to the current author, but plants are known to produce between 0-20 flowers, each containing up to around 20 achenes (ie single-seeded dry fruits), thus potentially each plant may produce up to 400 seeds. In a Canadian study, freshly collected seed kept moist germinated sporadically over a period of six months (Cook & Johnson 1968). In a survey of seed bank data in NW Europe, Thompson et al. (1997) reported 31 estimates for R. flammula, of which six regarded it as ephemeral, eleven short-term, and seven reckoned it produced a long-term seed bank (ie capable of surviving longer than 5 years).

Seedlings produce a rosette of leaves and if submerged they will also produce spreading stolons. In Canadian populations, flowering only occurred after the plant had been exposed to terrestrial conditions for an unspecified period of time (Cook & Johnson 1968).

European occurrence

R. flammula subsp. flammula is widespread in Europe except in both the southernmost and northernmost areas. It is absent from Iceland, and occurs at isolated stations only in Greece, Turkey, the Caucasus and W Siberia (Jalas & Suominen 1989, Map 1856; Jonsell et al. 2001). It extends south as far as N Africa and eastward to W Asia (Hultén 1958, Map 147). R. flammula is rare and probably accidentally introduced on the E and W coasts of N America (Jonsell et al. 2001) and it is a definite alien in New Zealand (Preston & Croft 1997).

Medicinal uses

R. flammula was another buttercup used in herbal medicine as a rubifacient for blistering, that is, for raising blisters. An ancient belief was that by irritating the skin and raising a blister, disease would be drawn out of the body. It was extensively used for this purpose during the bubonic plague in the 16th century, and was also used to treat scabs and running sores (Ui Chonchubair & Mhic Daeid 1995).

Threats

None.