Succisa pratensis Moench, Devil's-bit Scabious

Account Summary

Growth form

S. pratensis is a normally outbreeding species that in the phrase used by Grime et al. (1988, 2007), "displays a modest degree of phenotypic and genetic variation". It certainly is variably hairy, and it usually produces an erect, wintergreen, rosette-forming, perennial that is capable of growing up to 100 cm tall, or can become dwarfed to as little as 6 cm in height. The plant possesses an unusual short, vertical rhizome or rootstock that has long, stout roots. The short rootstock is the feature that gives rise to the plant's English common name, 'Devil's-bit Scabious'. Particularly in soils where the water table is often near the surface, the rootstock is extremely short (usually only 1-3 cm long) and, since it ends abruptly, it looks just like as if it has been bitten off. The plant rootstock from ancient times has had a high reputation as an 'All heal' herb, and the Devil was therefore held responsible for its truncation – hence the English name (Salisbury 1964; Vickery 1995).

The basal rosette leaves are ± elliptical or oblanceolate, margins usually entire, but occasionally distinctly toothed, the blades tapered into long stalks, up to 15 cm long. The leaves are hairy and are borne in opposite pairs. The rosette is attached to adventitious roots and it gives rise to a stem 6-100 cm long, often purplish at the base. The stem growth can also vary, from prostrate to decumbent, ascending or erect (Sell & Murrell 2006). Stems and leaves are thinly covered with long, rather stiff hairs. Stem leaves are also opposite, gradually narrowing upwards and becoming linear in shape.

Variation

While Adams (1955) in his British Ecological Society Biological Flora species account recognised that cytotypes and other forms of variation existed within S. pratensis, and noted that Baksay (1952) had described three varieties and several forms, not all of which had been found in Britain, no attempt was made to distinguish the variation with names. Similarly, the 3rd edition of The Flora of the British Isles (Clapham et al. 1987) did not make any mention of subdivision of the species, and Stace (1997, 2010 & 2019) and Parnell & Curtis (2012) in Webb's An Irish Flora have all followed suit.

However, no less than five varieties have been distinguished and named by Sell & Murrell (2006), on features such as differences in basal leaves (var. grandiflora (Rouy) P.D. Sell, known from only one site – a peaty woodland swamp in Sussex; dwarf stem up to only 7 cm, var. subacaulis (Bernardin.) P.D. Sell, found in Cornwall and some of the Western Isles in Scotland; stems prostrate, var. arenaria (Rouy) P.D. Sell, known only from cliff tops in two sites in Cardiganshire and the Mid Etudes, but also recorded from the coast of France; var. ovalis (Rouy) P.D. Sell, with large elliptical basal leaves plus a few small cauline (stem) leaves – known only from hay meadows in Oxfordshire; and the common, widespread form, var. pratensis, large basal leaves with reduction in size upwards on the stem.

Preferred habitats

S. pratensis occurs in a wide variety of habitats, soil types and light/shade conditions, favouring mildly acidic, moist to moderately well-drained situations. The range of habitats is quite remarkable, taking in arctic-alpine grassland, mountain rocky ground, rides and tracks in deciduous woods (apart from Beechwoods), low fertility pastures, fens, bogs, roadside banks and verges, by paths, river and stream banks, sandy or marshy ground near coasts, including dunes, heaths and sea-cliffs. It has also been recorded occasionally in artificial (ie man-made) habitats, including churchyards, graveyards and disused quarries. However, due to pressures on semi-natural vegetation from the effects of drainage operations and years of fertiliser use on farmland, S. pratensis populations are declining in many places and are increasingly becoming restricted to linear, lowland habitats, such as along railway and roadside banks and the sides of ditches and streams (Grime et al. 1988, 2007).

The species avoids droughted sites and shows a definite preference for continuously moist habitats with soils of intermediate pH in the range 5.5 to 6.5 (Adams 1955; G.T.D. Wilmore, in: Preston et al. 2002; Green 2022). In general, it is mainly found at altitudes below 350 m, but in areas of carboniferous limestone it can climb to ground around 970 m in parts of Wales (Grime et al. 1988, 2007; G.T.D. Wilmore, in: Preston et al. 2002).

It is a slow-growing, not particularly gregarious species, often appearing isolated as just a few scattered individuals or appearing in small populations. Adams (1955) described it as being, "always over-dispersed". It grows particularly well in habitats where potentially dominant competitors are kept in check by factors such as low fertility, moderate grazing pressure, marginal areas of ground and slopes on thin soils supporting sparse but continuous vegetation, or situations where other forms of moderate disturbance help keep ground open for colonisation by limiting the growth of more vigorous species (Adams 1955; Grime et al. 1988, 2007). The established strategy of S. pratensis is categorised as intermediate between that of a Stress-tolerator (S), and a more balanced C-S-R combination of all three recognised strategies, Competitor, Stress-tolerator and Ruderal (Grime et al. 1988, 2007).

Reproduction

Regeneration in S. pratensis is chiefly by seed, which germinates mainly in spring, although Adams (1955) reported seedlings appearing, "on a permanent quadrat [ie a small, experimental plot kept under observation] at almost all times of year". Seeds naturally require vegetation gaps in order to germinate and establish the plant in existing turf and thus some form and degree of habitat disturbance, such as light grazing, occasional mowing and/or light trampling, is necessary to allow population recruitment and long-term species persistence. The flattened basal rosette leaves of established S. pratensis plants are well adapted to withstand both light grazing pressure and trampling (Adams 1955).

Apart from seed reproduction, vegetative spread does sometimes occur by means of spreading lateral shoots, but this feature is seldom observed in the wild (Grime et al. 1988, 2007).

Flowering reproduction

Time of flowering varies considerably across B & I, but it mostly occurs late summer, in August and September. Hemi-spherical, cushion-like flower-heads (capitula), up to 2.5 cm in diameter, each terminal head containing around a 100 tightly packed florets and lateral heads with fewer florets. The inflorescences are borne on long, slender, peduncles on flowering stems that overall are around 60-90 cm tall. The flower-heads are usually dark blue to purple, but rarely they can also be white or pink. Unlike Knautia arvensis (Field Scabious), the outer petals of flowers on the rim of the inflorescence are not enlarged. The flowers are of two types, however, either bisexual or entirely female (ie the species is gynodioecious), and the heads are surrounded underneath (ie subtended) by an involucre composed of two or more rows of narrow green bracts. The small individual florets are also each subtended by a narrow bract and a little cup-like 'involucel' with five teeth. The calyx sits on top of the inferior ovary and it too is deeply lobed into four or five sharp, bristle-like, black teeth (Melderis & Bangerter 1955; Hutchinson 1972).

The bisexual flowers contain four stamens and a slender style and they are protandrous (ie male first, female later on). The flowers secrete nectar and are highly attractive to a wide range of bee, butterfly and moth pollinators. While selfing is possible in S. pratensis, it is believed to be very rare (Adams 1955; Proctor et al. 1996). Flowers can still be observed on plants right up until the middle of November, but it is unlikely they would produce seed this late on in the year. The ability to flower and the degree of flowering success are both affected by factors such as shading and competition (Adams 1955).

Seed production and dispersal

Fruiting success is very variable, yet the average plant produces around 850 single-seeded dry fruits (ie achenes or nutlets) per season (Salisbury 1964). Adams (1955) found the number of capitula on a flowering stem varied from one to ten in natural or semi-natural habitats, and the number of flower stems in his study was normally two per plant in the field, although one might be suppressed.

The nutlets or achenes are shed with a persistent, funnel-shaped epicalyx, overtopped by the true calyx with its four or five bristle-like teeth (Press & Short 1994). Despite this rather elaborate fruit structure, there is no well-defined dispersal mechanism and most fruits are dropped close to the parent plant. Some may be carried slightly further by wind, float off in running water, or attach themselves, however temporarily, to wool, fur or feathers of passing animals. Bullfinches have been observed pecking at the fruiting capitula and they may thus help to disperse the seeds (Adams 1955).

Possible seed longevity

The evidence regarding propagule survival in the soil seed bank is decidedly mixed: the survey of NW Europe seed banks lists 15 estimates, eleven of which suggest it is transient (surviving less than one year), two indicate short-term persistence (surviving at least one year but not more than five), one estimate suggests long-term persistence (surviving for at least five years), and one study recognised seed was present in the soil, but could not assign it to one of the previous three categories (Thompson et al. 1997). The majority view is most likely correct in most circumstances, but in particular situations, longer survival may be possible. Most seed simply overwinters, with germination occurring in the following spring. Clearly aspects of the ecology of the species, such as seed production, dispersal and establishment, would repay further study.

Fermanagh occurrence

S. pratensis is very frequent and widespread in Fermanagh being present in 424 tetrads, 80.3% of the VC total. It is the 13th most frequently recorded plant in the Fermanagh Flora Database. While Devil's-bit Scabious is regularly found on roadsides, hedge banks, in woodland clearings, by paths and in marshy grasslands and fens throughout the Fermanagh lowlands, it is even more typically found in damp to moderately wet, acidic, nutrient-poor, Molinia caerulea-dominated upland heaths, cliffs and boggy grasslands. It is, however, least likely to occur in completely waterlogged or regularly droughted soils, those of extreme pH, high fertility, or of a very disturbed nature.

Fossil history

Succisa pratensis has a long fossil fruit and pollen record in the British Isles from the Pastonian interglacial onwards. It has survived either in situ throughout successive glaciations, or has quickly spread under open periglacial conditions (presumably by wind), immediately after ice retreats (Godwin 1975). Having said this, it should be remembered that S. pratensis has no obvious means of fruit and seed dispersal mechanism and most of its seeds are very probably only transient in soil. Thus rapid colonisation by S. pratensis in most circumstances would appear unlikely in competition with better adapted species. On the other hand, in situ survival in the near vicinity of glacier ice is even more difficult to imagine!

British and Irish occurrence

S. pratensis is a widespread, abundant and, in August and September, conspicuous wildflower throughout most of B & I. Although the New Atlas hectad map indicates major losses of this species in S & E England, presumably due to agricultural 'improvements' in both grasslands and on heaths, this decline is not yet found elsewhere to any very noticeable distributional extent and certainly it is not the case in Fermanagh (New Atlas; Braithwaite et al. 2006).

Being a plant of infertile, relatively undisturbed soils and of a stress-tolerant survival strategy with poor dispersal ability, and little in the way of, or no long-term seed bank, populations of S. pratensis throughout these islands have been squeezed hard in many lowland sites by widespread changes in agriculture involving both drainage and the increased use of fertilizers (Grime et al. 1988, 2007). The less intensive agricultural regime typical of most of Fermanagh, taken with the European Community environmental friendly farming subsidy scheme (ESA), together helped to reduce the threat to species such as Devil's-bit Scabious, at least in the wetter, more upland western parts of Fermanagh. How environmental matters will change now that the UK has left the EC and its agricultural support mechanisms, and what the previous support will be replaced by is a chapter that remains to be read in the next decade.

The local Succisa pratensis population is of conservation importance, through being the specific food plant of the caterpillar of the Marsh Fritillary butterfly. This insect occurs at several sites in Fermanagh and it is a protected, declining species.

European and world occurrence

Beyond B & I, S. pratensis is common throughout most of Europe except for the extreme north, the mountain interior of Scandinavia and parts of the Mediterranean region – where, in particular, it is chiefly absent from the islands. It does occur, however, in Iceland, the Faeroes and the Azores, and it stretches south to Madeira and N Africa, and eastwards to the N Caucasus and Middle Siberia. It is also an introduction in eastern N America, around Louisburg and Cape Breton Island and the Cameroons in W Africa (although the Cameroon's mountain form might possibly be a separate species) (Adams 1955; J.F.M. Cannon, in: Tutin et al. 1976; Hultén & Fries 1986, Map 1745; Press & Short 1994).

Uses

As indicated above, herbalists believed that S. pratensis had a wide range of healing properties – diophoretic (ie caused sweating), demulcent (ie soothed irritation) and febrifuge (ie fever reducing). As such, it was used to soothe and combat coughs, fevers and internal inflammation, and as a skin cleanser and blood purifier it had both external and internal benefits. It was believed it could cure ailments as diverse as the plague and dandruff, and it was also recommended against fevers, poisons, venomous bites, venereal diseases and all kinds of physical wounds and sores. It was therefore prized as a valuable 'cure-all' or 'all-heal' herb (Grieve 1931; Le Strange 1977). Although perhaps still used in homoeopathy, despite its many past uses S. pratensis appears to have been dropped by modern herbalists, perhaps due to its ill effects on patients with gall stones, liver complaints, gastric ulcers or a weak stomach.

After a prolonged Internet search, RSF has been unable to discover much regarding the active ingredients of S. pratensis other than it contains tannins, saponins, a beta-methyl glycoside called 'scabioside' (which may still be used in Chinese medicine) and something called 'amidon' (Launert 1981).

In Ireland and Scotland, the plant appears to have been also used as a source of blue dye for textiles, the leaves being prepared in the same manner as woad (Riley 1997).

Having basal leaves of rather thick texture, in some parts of B & I, S. pratensis was referred to and used in the past like Plantain is, as 'Fire-leaves' by farmers examining and estimating whether or not the field moisture of their meadows was suitable for hay making. This involves pulling a handful of S. pratensis leaves and violently twisting them to see if any water could be squeezed out. If it can be, the moisture level of the meadow is too high, since hay cut at this stage of moisture content is liable to ferment in the rick and could result in spontaneous combustion, hence the name 'Fire-leaves' (Vickery 1995).

Names

The genus name 'Succisa' derives from Latin, not Greek, the origin being 'succido', and its past participle 'succisus', meaning 'to cut off below'. This is another reference to the curiously truncated rhizome of the plant, for which the poor old Devil gets blamed. Previously this plant was regarded as part of the genus 'Scabiosa', the name being derived from Latin 'scabies', referring to 'the itch', which is itself derived from 'scabiosus', meaning 'rough and scurfy'. The roughness is probably a reference to the hairy texture of the leaves – a feature which much better fits Scabiosa columbaria (Small Scabious) and Knautia arvensis (Field Scabious) than it does Succisa pratensis. By analogy and the precepts of the famous (or infamous) herbalist, 'Doctrine of Signatures', the rough hairiness meant the plant was supposed to cure scabies (a form of leprosy) and other itching diseases (Grieve 1931; Gilbert-Carter 1964; Stearn 1992).

The Latin specific epithet 'pratensis' is derived from 'pratum', meaning 'meadow' and, as ever, it means 'growing in a meadow' (Gilbert-Carter 1964).

Having so many herbal medicinal uses it is not surprising that S. pratensis (= Scabiosa succisa) has a list in Grigson's (1955, 1987) Englishman's Flora of no less than 26 English common names, and even this is not exhaustive (Prior 1879; Britten & Holland 1886). Apart from the legend referring to the Devil (who was also known derogatively as 'Curly-head' or 'Curl-doddy'), biting off the rhizome or rootstock (eg 'Forebit', 'Forbitten More' and 'Ofbit'), many of the remaining English common names refer to the colour and form of the inflorescence. The latter names equally well applied to Knautia arvensis and other similar relatives, eg, 'Blue Bobs', 'Blue Bonnets', 'Angel's pincushion', 'Bachelor's Buttons' and 'Woolly Hardhead'. One of the other names refers to the plant's pollinators, 'Bee-flower'. An attractive poetic name from Sussex is 'Blue Kiss', for which the current author (RSF) can offer no explanation, except perhaps the 'Bachelor's Buttons' tradition whereby a girl would pick the button-like flowers, give each one a suitor's name and then choose her preferred husband by the one which flowered best (Grigson 1955, 1987)!

Threats

None.

References

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