Odontites vernus (Bellardi) Dumort., Red Bartsia

Account Summary

Growth form and preferred habitats

O. vernus is a stiff, erect, freely branched, annual, 30-50 cm tall, with wiry, 4-angled stems bearing opposite leaves that are stalkless, narrow, linear-lanceolate, margins rather remotely toothed and surfaces heavily hispid with short, bulbous-based hairs. The flowers are a dull or pale purplish-red, but albinos also commonly occur.

Red Bartsia is a hemi-parasite, attaching its fibrous roots to the roots of grasses and purloining a proportion of their assimilates to assist its own growth and reproduction. In general, semi-parasites are comparable to unspecialised parasites and since most attach themselves to the roots of grasses there must be comparatively little risk of the seeds not being near a suitable host plant (Salisbury 1942).

In common with other ruderals, O. vernus is often associated with disturbed sites such as sandpits, quarries and neglected or derelict waste ground, eg locally in Fermanagh around the disused railway station at Maguiresbridge. The established strategy of O. vernus is categorised as R/CR, ie intermediate between a straight Ruderal species and a Competitive Ruderal (Grime et al. 1988, 2007).

O. vernus colonises a wide range of soils from the decidedly damp to the very dry, although some lakeshore sites may be variable in this respect, becoming dry in summer, yet winter wet. It appears to prefer somewhat heavier clay or loam soils that are moderately acid to calcareous and sunny (Salisbury 1964; Sinker et al. 1985). Being a relatively poor competitor when among perennial weeds in open communities, although more competitive than some ruderal annuals, it is not surprising that Red Bartsia is absent from more fertile soils, except where they are trampled, heavily overgrazed (eg by cattle or, more likely, horses) or otherwise regularly disturbed. Thus O. vernus is quite often found occupying bare patches in moderately grazed, short-turf, permanent grassland, or on the margins of arable fields (although these are rare nowadays in Fermanagh). Other sites are open situations around field gateways and in vegetation gaps on trampled or otherwise regularly disturbed ground, such as along wayside grass verges. Presumably these environments allow it to avoid competition from vigorous established perennials in more closed, taller, denser vegetation (Sinker et al. 1985).

Flowering reproduction

O. vernus flowers from June to August (Garrard & Streeter 1983). The flowers, 8-10 mm long, are held in long, leafy one-sided racemes terminal on the stem and side branches. The individual flowers are tubular, two-lipped, about 1.3 mm long and softly hairy. The four hairy anthers are held close together, slightly exserted from the mouth of the corolla tube; the anthers are aptly described as, "peeping out from under the hood of the upper corolla lip" (Hutchinson 1972). The style is long, slender and hairy. Pollination is carried out by bees and occasional butterflies (Proctor & Yeo 1973). The small brown seeds are roundly ovoid, 1.5 mm long, with longitudinal whitish ribs and fine transverse ridges connecting them. The fruit capsule is oblong and pubescent and is surrounded by the persistent calyx. Each capsule contains about 15 seeds which are shed in autumn but do not germinate until early in the following spring. Some seed is also long-term persistent in the soil seed bank (ie surviving more than five years) (Butcher 1961; Salisbury 1964; Clapham et al. 1987; Thompson et al. 1997).

The range in size of individual plants is considerable, the largest specimens examined by Salisbury (1942) bore 445 capsules and the smallest just nine. The mean capsule number on 124 specimens was 112 per plant and the mean seed number was 14.8 per capsule, with a range from 1-36. The mean seed output was therefore approximately 1,660 ± 105 seeds per plant (Salisbury 1942).

Variation

O. vernus (= Bartsia odontites L.) Hudson, O. rubra Gilib.) is a very variable species which is difficult to separate adequately into infraspecific entities. Sometimes segregates are treated as subspecies and at others as species. Three subspecies of O. vernus are now recognised (Stace 1991, 1997), but they have not been distinguished by most of the recorders working in Fermanagh.

Subsp. vernus has stems to 25 cm, with 1-4 pairs of branches, but occasionally has no branches in starved plants. It also has its lowest flower at node 6-9 and leaves lanceolate and distinctly toothed. It is recorded from most of B & I, but there are many recording errors involved in parts of the S of England and Wales; it is scattered in Ireland, Wales and N Britain. Subsp vernus replaces subsp. serotinus in most of C & N Scotland and it is mainly aestival (summer flowering).

Subsp. serotinus (Syme) Corb. has taller stems, 2-50 cm, with 2-8 pairs of branches spreading at right angle and with their tips often upcurved. Leaves are linear-lanceolate, somewhat narrowed at the base, margins obscurely toothed. It is considered frequent over most of B & I, except in C & N Scotland. It is the only subspecies in most of C & S Britain, and its flowering is mainly autumnal (Stace 2019).

In the Fermanagh Flora Database, there are a total of just 19 records of subsp. serotinus, and as the tetrad map for this taxon shows, it is widely scattered across 16 tetrads. This form of the plant is considered to be autumnal (Stace 2019). As the map for subsp. serotinus illustrates, a solitary record (made by the late Nora Dawson at Aghiver, just N of Castle Archdale in April 1976) has a post-1975 date.

It is claimed that the majority of Irish O. vernus plants belong to subsp. serotinus (Hackney et al. 1992), but the current author (RSF) and RHN have not examined the local situation in Fermanagh and therefore cannot make any pronouncement.

The third subspecies, subsp. litoralis (Fr.) Nyman (= O. vernus subsp. pumilus auct. non (Nordst.) A. Pedersen), is a dwarf coastal form with stems to 20 cm, 0-3 pairs of branches and the lowest flower at node 4-8. It occurs on gravelly and rocky sea-shores and in saltmarshes on the coasts of N & W Scotland from Kintyre (VC 101) to Shetland (VC 112), Westmorland (a salt-marsh at Askam-in-Furness) (VC 69) and Merioneth on the W Wales coast (VC 48). It is described as aestival (ie summer flowering) (Snogerup 1982; Halliday 1997; Stace 2019).

Fermanagh occurrence

The species has been recorded in 103 Fermanagh tetrads, 19.5% of those in the VC. Apart from disturbed permanent pasture situations, locally it is mainly recorded on roadsides and along upper lakeshore grasslands. As the species tetrad distribution map shows, it is thinly scattered throughout Fermanagh, but apparently more frequently around Upper Lough Erne. The excessively detailed sampling of the latter region produced by the EHS Habitat Survey in 1986-7 has significantly skewed the overall species representation towards this area of the county and, therefore, this concentration of O. vernus records should not be taken too seriously.

British and Irish occurrence

Widely distributed throughout B & I. Of the three subspecies, subsp. vernus is commonest in northern Britain, but only local and infrequent in the south. Subsp. serotinus is common in southern England, but is rare or absent from much of N Scotland. Subsp. litoralis is a dwarf plant confined to coastal grassland in a few places in N Scotland and the Outer Hebrides (Garrard & Streeter 1983; Clapham et al. 1987).

European and world occurrence

O. vernus is well distributed across temperate Europe and Asia, although while present in most of the W Mediterranean, it is absent from the eastern portion of the basin. The distribution thins markedly northwards of S Scandinavia, although it is not entirely absent. It is present in eastern N America, but not native there (Hultén & Fries 1986, Map 1684).

Names

The genus name 'Odontites' was a name used by Pliny for a plant regarded as 'good for toothache' derived from the Greek 'odonto', or 'odons', 'a tooth' and the Greek meaning 'connected with' (Gilbert-Carter 1964). The Latin specific epithet 'vernus' means 'spring flowering' (Gledhill 1985).

The English common names include 'Eyebright', 'Eyebright Cow-wheat', 'Red Eyebright', 'Red Odontites', 'Cock's comb', 'Hen-gorse', 'Poor Robin', 'Sanctuary' and 'Twiny-legs' (Grigson 1955, 1987; Melderis & Bangerter 1955). Grigson is particularly dismissive of the plant, regarding it as having no strong characteritics, "No peculiarities, no beauties, no virtues. A red, dullish, disregarded annual of the cornfields, a weed which has not even incurred the hatred of farmers." (Grigson 1955, 1987).

Threats

None.

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