kingdom Plantae - plants »  divisio Magnoliophyta - flowering plants »  class Rosopsida - eudicots » order Malpighiales »  family Violaceae »  tribus Violeae > genus Viola > Viola sect. Viola  L. > Viola subsect. Rostratae Kupffer    

Viola pumila Chaix - Meadow Violet

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Synon.: Viola pratensis Mert. & W. D. J. Koch 

Common names: Viola minore, Violette naine, Niedriges Veilchen, Meadow violet, dvärgviol,  Фиалка низкая 

Description:  Hemicryptophyte. Rhizomatous, caulescent perennial. Rhizome vertical, branching at or below the soil surface, covered with numerous brown stipules; terminal leaf rosette absent. Aerial stems ascending, to 15(–20) cm, glabrous. Stem leaves 3–7; stipules narrowly lanceolate or oblanceolate, those of the upper leaves to 30 mm, 0.8–2 times as long as the petiole, green with distinctly dark veins, entire or with a few coarse teeth; petiole to 3 cm, shorter towards the top of the stem, glabrous, shorter than the blade, 0.5–1.3 times as long as the stipules; blade of middle and upper leaves narrowly ovate to narrowly lanceolate, 15–40 × 5–17 mm, 2–3.5 times as long as wide, dark green, glabrous; margin faintly crenate with 8–12 obtuse, low teeth or near the base with forwards-pointing teeth; base cuneate, narrowly decurrent onto the petiole; apex acute to obtuse.

Chasmogamous flowers scentless, from the middle or upper part of the aerial stems. Pedicels glabrous, to 10 cm, longer than the subtending leaves; bracteoles subulate, in the upper half of the pedicel. Sepals lanceolate, acute, upper ones 5–7 × 1–2 mm, lateral ones 5–8 × 1.5–2.5 mm (in both cases excluding the appendage); appendage suborbicular to truncate, in upper sepals 0.9–1.6 × 0.7–1.3 mm, in lateral sepals 1–2 × 1.5–2.2 mm, all 0.16–0.33 times as long as the rest of the sepals. Corolla 13–17 × 13–16 mm, as high as wide, flat in front view. Petals whitish to light violet; upper petals recurved, obovate, obtuse, 9–12 × 3.5–5.5 mm, 2–3 times as long as wide; lateral petals obovate, obtuse, 10–12 × 3.5–5 mm, 2.2–3 times as long as wide; spurred petal 9–12 × 4–6 mm excluding the spur, 1.6–2.5 times as long as wide; spur greenish, conical, blunt, straight or slightly curved downwards, 2.5–4 × 1.5–2.5 mm, 1.2–2 times as long as wide, 1.8–4 times as long as the sepal appendages. Style not papillose. Cleistogamous flowers 3–4 mm. Capsule ovoid, trigonous, obtuse, 6.5–9 mm, glabrous, explosive. Seeds ovoid, 1.6–1.9 × 0.7–1 mm, pale to dark brown; elaiosome small. – Mid-spring to late spring (chasmogamous flowers), summer (cleistogamous flowers).

2n=40 (S Sk). – [2n=40] 

Distributional Range: Native Asia-Temperate SIBERIA: Russian Federation, [Tuva, Krasnoyarsk, Evenk, Irkutsk] Russian Federation-Western Siberia [Western Siberia] MIDDLE ASIA: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan Europe MIDDLE EUROPE: Austria, Czechoslovakia, Germany, Hungary, Poland, Switzerland EASTERN EUROPE: Belarus, Estonia, Latvia, Lithuania, Moldova, Russian Federation-European part, [European part] Ukraine SOUTHEASTERN EUROPE: Bulgaria, Former Yugoslavia, Italy, Romania SOUTHWESTERN EUROPE: France

Habitat:  Seasonally wet places in open, calcareous grassland, especially in mats of Carex hostiana, Molinia caerulea or Sesleria uliginosa in alvar depressions, but also in semi-shade in forest glades; more rarely among fruticose lichens on dry alvar gravel. In Sk Eskilstorp, V. pumila grew on ant-heaps in grazed seashore meadow. Prati erbosi umidi di pianura, da 0 a 200 m  

Taxonomy. Viola pumila is a tetraploid based on x=10 (a number originating from ancient polyploidization of taxa with x=5). Apparently it originated from hybridization between V. stagnina, or a similar taxon, and another taxon that no longer occurs in Europe (Moore & Harvey 1961).

Hybridization. Hybrids of Viola pumila are known with V. canina ), V. elatior , V. reichenbachiana), V. riviniana , V. rupestris subsp. rupestris  and V. stagnina.

References:

1. Aldén, B., S. Ryman, & M. Hjertson. 2012. Svensk Kulturväxtdatabas, SKUD (Swedish Cultivated and Utility Plants Database; online resource) URL: www.skud.info

2. Czerepanov, S. K. 1995. Vascular plants of Russia and adjacent states (the former USSR) Cambridge University Press.

3. Huxley, A., ed. 1992. The new Royal Horticultural Society dictionary of gardening

4. Komarov, V. L. et al., eds. 1934-1964. Flora SSSR.

5. Pignatti, S. 1982. Flora d'Italia.

6. Tutin, T. G. et al., eds. 1964-1980. Flora europaea.