Lesser Spearwort

In Great Britain and/or Ireland:
Foodplant / open feeder
larva of Bagous brevis grazes on leaf of Ranunculus flammula
Other: sole host/prey

Foodplant / parasite
Erysiphe aquilegiae var. ranunculi parasitises Ranunculus flammula

Foodplant / parasite
sporangium of Peronospora ranunculi parasitises live Ranunculus flammula
Other: minor host/prey

Foodplant / miner
larva of Phytomyza ranunculi mines leaf of Ranunculus flammula

Foodplant / spot causer
hypophyllous, in small groups aecium of Puccinia magnusiana causes spots on live leaf of Ranunculus flammula

Foodplant / spot causer
amphigenous, but mainly epiphyllous colony of Ramularia anamorph of Ramularia didyma var. didyma causes spots on live leaf of Ranunculus flammula

Foodplant / spot causer
amphigenous, immersed, black, subshining pycnidium of Septoria coelomycetous anamorph of Septoria ficariae causes spots on leaf of Ranunculus flammula
Remarks: season: 5-7

Foodplant / spot causer
densely aggregated, mostly epiphyllous, immersed then emergent, black pycnidium of Septoria coelomycetous anamorph of Septoria polaris var. scotica causes spots on fading leaf of Ranunculus flammula
Remarks: season: 7

In Eurasia, this taxon is usually treated as two closely related species. Ranunculus flammula in the strict sense has relatively stout (0.8-3 mm thick) stems that are erect or ascending from prostrate bases, lanceolate to oblanceolate leaves 3-10 mm broad, sepals 3-4 mm, and petals 5-7 × 3-4 mm. Ranunculus reptans has slender (0.2-1 mm thick) stems that are usually prostrate except for the pedicels, leaves linear or filiform, to 2 mm broad, sepals 1-2 mm, and petals 3-5 × 1-2.5 mm. In North America, this distinction holds up relatively well east of the Great Plains, where plants with the characteristics of R . flammula in the strict sense are found in eastern Canada (Newfoundland and northern Nova Scotia) while plants with the characteristics of R . reptans are widespread. In the western part of the continent, however, the situation is much less clear. Collections from the Great Plains and Rocky Mountains resemble R . reptans in most characters, but they often have broader leaves (up to 5 mm broad). Plants from farther west are very confusing; specimens showing the typical morphology of R . flammula in the strict sense and R . reptans are found over a wide area, but most specimens from this area combine the characteristics of the two taxa in various ways. For this reason, it is not possible to separate these taxa at the species level. Three varieties are usually recognized, but further study will probably alter the varietal classification (see comments below, under R . flammula var. ovalis ).

Stems erect to prostrate, usually rooting nodally, glabrous or sparsely strigose. Roots not thickened basally, glabrous. Proximal cauline leaf blades lanceolate to oblanceolate or filiform, 0.7-6.5 × 0.04-1 cm, base acute to filiform, margins entire or serrulate, apex acute to filiform. Inflorescences: bracts lanceolate to oblanceolate. Flowers: receptacle glabrous; sepals 5, spreading or weakly reflexed, 1.5-4 × 1-2 mm, glabrous or appressed-hispid; petals 5-6, 2.5-7 × 1-4 mm; nectary scales glabrous. Heads of achenes globose or hemispheric, 2-4 × 3-4 mm; achenes 1.2-1.6 × 1-1.4 mm, glabrous; beak lanceolate to linear, straight or curved, 0.1-0.6 mm.

Ranunculus reptans has slender (0.2-1 mm thick) stems that are usually prostrate except for the pedicels, leaves linear or filiform, to 2 mm broad, sepals 1-2 mm, and petals 3-5 × 1-2.5 m

In Eurasia, this taxon is usually treated as two closely related species. Ranunculus flammula in the strict sense has relatively stout (0.8-3 mm thick) stems that are erect or ascending from prostrate bases, lanceolate to oblanceolate leaves 3-10 mm broad, sepals 3-4 mm, and petals 5-7 × 3-4 mm.

Ranunculus flammula, the lesser spearwort, greater creeping spearwort or banewort, is a species of perennial herbaceous plants in the genus Ranunculus (buttercup), growing in damp places throughout the Boreal Kingdom. It flowers June/July. Ranunculus flammula is poisonous. It is very closely related to R. reptans, which is distinguished by prostrate and more slender stems, narrower leaves and smaller flowers and is sometimes included within R. flammula sensu lato as a variety (R. flammula var. reptans (L.) E. Meyer).

In addition to other forms of pollination, this plant is adapted to rain-pollination.