- Name also: Grassleaf Speedwell, Skullskap Speedwell (USA)
- Family: Plantain Family – Plantaginaceae
(formerly Figwort Family – Scrophulariaceae)
- Growing form: Perennial herb. Rootstock creeping.
- Height: 10–50 cm (4–20 in.). Stem ascending–erect, glabrous or sometimes hairy.
- Flower: Corolla almost regular (actinomorphic), pale blue–purple, sometimes white, streaked, 5–6 mm (0.2–0.24 in.) broad, fused, 4-lobed, wheel-shaped, short-tubed. Calyx 4-lobed, lobes with glandular hairs–glabrous. Stamens 2. Pistil a fused carpel. Inflorescence a lax, slack axillary raceme. Flower-stalk thin, much longer than subtending bracts.
- Leaves: Opposite, stalkless. Blade narrowly elliptic–linear, often brownish or reddish especially underneath, with entire margins or small-toothed.
- Fruit: Obcordate capsule, flat, 4 mm (0.16 in.) long, longer than calyx, with glandular hairs–glabrous.
- Habitat: Shores, waterside meadows that are prone to flooding, puddles, ponds, ditches, wet excavation sites, fields, fallow fields.
- Flowering time: June–August.
Genus Veronica has at least 160 species. In the wild in Finland these range from large, showy species to small annuals and creeping weeds on arable land. Marsh speedwell is in a class of its own, however: its limp shoots only stay erect by supporting themselves on other vegetation. The axillary racemes are just as slack, and they arch downwards at the latest as the flat, peltate fruit ripens.
Marsh speedwell is one of the more common species of its genus in Finland, but it is slender and is easily hidden by other vegetation. It is not found often by accident as it grows in different kinds of wet, swampy areas. The species’ natural habitats are open mud and clay shores and maybe rocky pools, but it has spread to places that people have influenced and is particularly common in ditches, excavation sites and other wet places. Marsh speedwell is usually glabrous but sometimes hairy specimens turn up. Hairiness is regarded as unsuitable in drier habitats, but there is no really convincing show of this – both forms can often be found growing side-by-side in the same habitat.