Veronica arvensis L., Wall Speedwell
Account Summary
Native, frequent, widespread and locally abundant. European southern-temperate, but widely naturalised in both hemispheres and now circumpolar southern-temperate.
1881-2; Barrington, R.M.; Devenish Island, Lower Lough Erne.
March to November.
Growth form and preferred habitats
In terms of reproductive strategy and life-history, V. arvensis is a winter- or less commonly, a summer-annual. Wall Speedwell is a very typical example of a stress tolerant, semi-rosette forming, weedy therophyte. The plants are very variable, stems ranging from 5-25(-40) cm in height, erect or decumbent, often branched from the base and developed on a fibrous root system. The small, ± triangular leaves (up to 15 mm) narrow upwards into the flowering part of the stem. They are downy or thinly hairy and their margins are coarsely and bluntly toothed, features that readily distinguish the plant from the common naturalised V. peregrina (American Speedwell) (Perring & Walters 1989; An Irish Flora 1996).
This weedy little annual is frequent and locally abundant in dry, open, sunny, potentially droughted, more or less disturbed, wayside sites where perennial competitors are excluded by the stressful growing conditions. Previously it was a common weed of arable crops and cultivated soil in general including gardens, but modern herbicides have reduced its presence considerably. It is very frequent on the tops of walls, or on dry, exposed, relatively infertile, bare ground near buildings, car parks, quarries, sand-pits and playing fields. Indeed, it can occur in any disturbed or stony, open, fully illuminated site, that offers bare soil of either a calcareous or moderate acidic nature within the near neutral pH range 6-8 and of almost any texture. In closed turf grasslands, it only colonises open, ± disturbed spots, such as anthills, which are avoided by most other species, or, alternatively, it colonises transiently available, recently disturbed bare, rocky soil (Grime et al. 1988, 2007).
Flowering reproduction
V. arvensis flowers from March to October or, indeed, in favourable sites, throughout the whole year. The numerous flowers are borne in long, but rather crowded, terminal racemes. The tiny, 2-3 mm diameter flowers, have bright blue or dark sky-blue petals with a whitish tube. The petals are much shorter than the hairy calyx. The flower pedicels are very short and the associated bracts are entire and longer than the flowers, hiding them to an extent.
The flowers attract insects such as flies and small bees as pollinators, or else they self-pollinate: the two anthers and the stigma being at the same level makes this easily happen (Fitter 1987). The fruit capsule is rounded, about as long as broad, 3.0 × 3.5 mm, notched and fringed with gland-tipped hairs. The seeds are 1.0 × 0.5 mm, flat, with radiating striæ, smooth and light brown (Butcher 1961; Hutchinson 1972; Garrard & Streeter 1983; Streeter et al. 2009).
Seed persists in soil for up to five years or so (Thompson et al. 1997), although often it is not produced in huge numbers. The average capsule contains only 18 seeds and the mean per plant is around 1,000 (Salisbury 1942). However, under optimal growing conditions, large plants may produce up to 17,000 seeds (Harris & Lovell 1974; Grime et al. 1988, 2007). As the species generally grows in exposed, open sites, dispersal is principally by wind. Although the plant is generally absent from grazed grassland sites, should it happen to be ingested, it is possible for seed to pass unharmed through the alimentary canal of cattle (Ridley 1930). As it frequently grows on or near anthills, it is very probable that ants help transport seed. Since it was a familiar weed of arable fields for many centuries, it is highly likely that dispersal in crop seed and human agency facilitated its worldwide spread.
Fermanagh occurrence

As the tetrad map indicates, Wall Speedwell has been recorded in 117 widely scattered Fermanagh tetrads, 22.2% of those in the VC. Sites include on the limestones above Florencecourt and the lower slopes of Cuilcagh mountain.
British and Irish occurrence and status
V. arvensis is widespread and common throughout most of B & I, being the commonest of a group of annual weedy Speedwells. It has traditionally been regarded as native, although in common with most other Veronica species, there is no fossil evidence to support this idea (Godwin 1975). Its weedy behaviour, long association with cultivation and spread beyond our shores by man, taken together suggest to the current author (RSF), grounds for suggesting it could be an archaeophyte. The New Atlas hectad map shows V. arvensis is very widespread in both B & I, except in the far NW of Scotland and the W of Ireland where unsuitable wet, acid peaty soils are predominant and cultivation is very rare or almost entirely absent.
European and world occurrence
Very widespread throughout most of Europe, C & W Asia, N Africa and Macronesia. It is regarded as having its origin somewhere here, but has spread as a crop weed throughout this area. It has been very widely introduced by agricultural and trading man in E Asia, S Africa, N & S America, S Australia and New Zealand, so that the present distribution is discontinuous circumpolar (Hultén & Fries 1986, Map 1654).
Names
The Latin specific epithet 'arvensis' is derived from 'arvum (solum)', meaning 'arable land', suggesting the species grows mainly on arable land (Gilbert-Carter 1964).
Threats
None.