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Silene latifolia Poir., White Campion

Account Summary

Introduction, archaeophyte, extremely rare and almost certainly extinct. Eurosiberian southern-temperate, but widely naturalised and now circumpolar, also introduced in Tasmania and New Zealand.

1947; MCM & D; rubbish tip near Enniskillen.

Growth form and preferred habitats

In good growing conditions this conspicuous, short-lived wintergreen perennial, or occasionally annual or biennial develops a taproot more than 40 cm deep and flowering branches up to 100 cm tall. It is not completely frost hardy in Britain & Ireland (Salisbury 1964), but it is extremely resistant to drought (Baker 1947). Like S. vulgaris (Bladder Campion), it develops a thick, almost woody rootstock from which a number of short, non-flowering shoots and taller, erect, robust, flowering stems arise. Shoots are covered with soft hairs, long ones below, short and mostly glandular, but not sticky above (Baker 1947).

It is a weed of arable fields and their margins that also occurs on other man-made, dry, well-drained, ± exposed ruderal habitats, including roadside verges, hedge banks, disturbed ground in waste places and the base of walls. It is especially associated with harbours and ports. S. latifolia tolerates dry, light, sandy soil conditions, but thrives best in deep, well-drained, near-neutral pH, lowland calcareous substrates, in sunny, open situations (Salisbury 1964). Nowadays in many sites it typically occurs solitary, or as a few scattered individuals, and it only rarely forms small patches (Baker 1947; Clapham et al. 1987; Jonsell et al. 2001).

Cattle, horses and sheep graze the plant, but rabbits do not. Plants usually regenerate rapidly after browsing. S. latifolia stems are easily broken by trampling at the flowering stage, but leaf rosettes survive intermittent trampling (Baker 1947).

Flowering and vegetative reproduction

White Campion is a long-day plant, and has a prolonged flowering season. Flowering extends from April or May in the south, until October, or November in sheltered situations (Baker 1947). Peak flowering is from June to August. The inflorescence of S. latifolia is lax with spreading branches. Technically, it is a dichasial cyme, but with monochasial upper parts! The species is dioecious, having separate male and female flowers. Male flowers bloom earlier than female, and they also persist later. Unlike S. vulgaris (Bladder Campion), perfect, bisexual flowers are very rare in S. latifolia. The flowers are large, about 30 mm across. Female flowers have an urn-shaped or subglobose and inflated calyx, while in male flowers the calyx is campanulate or ± cylindrical. The male plants bear more numerous, slightly nodding flowers than females. In both sexes, the calyx is covered with downy, slightly sticky hairs.

The white petals are deeply two-lobed, and flowers release a slight perfume and provide nectar at night to attract noctuid moths as pollinators (Jonsell et al. 2001). Crawling insects are excluded by a constriction at the mouth of the corolla tube. As in S. vulgaris, long-tongued bees visit in daytime, collecting any remaining nectar, and they may help pollinate the flowers. Short-tongued bees regularly steal nectar by making a hole near the base of the flower tube (Baker 1947). Some noctuid moths of the genus Hadena are serious parasites, laying eggs in the female flowers and causing severe reduction in seed production in affected flowers (Baker 1947; Pettersson 1991).

The fruit capsule is cylindrical to broadly ovate and it becomes leathery as it ages. In summer, the capsule ripens around four to five weeks after flowering. It splits open, forming ten slightly spreading teeth. The dry seeds are shaken out by wind, the capsule behaving like a censer. In wet weather, the capsule teeth tend to bend inwards, keeping the seed dry and preventing them from getting wet and sticking together (Baker 1947). The typical plant produces between 16-20 fruits, but a large plant could set close to 100 capsules, each containing between 50-400 seeds (Baker 1947; Salisbury 1964).

The fact that S. latifolia, like some plants of S. vulgaris, bears unisexual flowers only, very probably reduces the amount of seed set when the plant is scarce in a geographical area. Inevitably, low seed production will lead to, or hasten, local extinction of the species. This is particularly the case with a plant like White Campion that has no specialised structures adapted for vegetative reproduction. Having said this, partially uprooted plants of S. latifolia, eg as a result of ploughing, are able to produce elongated leafy stolons that can re-establish the plant in under a fortnight given suitable growing conditions (Baker 1947). Only the buds on the root crown permit vegetative regeneration (McNeill 1977), and in the normal habitat situation, vegetative reproduction of any description is too slow for anything more than establishment of existing colonists (Baker 1947).

Seed production

Seed set is generally good and in England, an average sized female plant of S. latifolia will often produce around 5,000 seeds. Larger plants can manage up to perhaps three times this figure (Salisbury 1964). Seed output estimates in N America vary widely, but at best they are more than double Salisbury's estimate (McNeill 1977). Seed are grey or black, bluntly tuberculate and about 1.5 mm long (Baker 1947). Seed shed in early summer can germinate the same season, or they may do so the following spring, or later.

Seed survival

As with many other members of this family, S. latifolia seed can survive dormant in undisturbed soil for up to 20 years (Lewis 1973). Despite this fecundity, S. latifolia is essentially a species of sunny conditions, well adapted to dry soils and is extremely drought resistant. It does not cope well with damp, humid conditions, however, since attack by Fusarium species cause seeds to rot and seedlings to damp off (Baker 1947). This alone, or in combination with other factors, including a marked decline in arable agriculture and improved seed hygiene, helps explain why White Campion is so seldom met in northern and western parts of these islands.

Variation and taxonomy

There is a cline in variation from E to W in Europe with respect to a range of characters, including seed ornamentation (Jonsell et al. 2001). Variation within the Silene vulgaris aggregate and in related species including S. latifolia has occasioned numerous changes in classification and nomenclature over the years. Silene latifolia has been in two other genera, namely Lychnis and Melandrium.

Fossil record and centre of origin

The fossil record in Britain stretches back only to the Early Bronze Age (Godwin 1975). The species most probably arose from an ancestor more closely resembling S. dioica (Red Campion) by eco-geographical divergence. It has dispersed from a centre of origin somewhere in the Middle East, the Mediterranean and C Europe, where it grows in dry, sunny, natural habitats. S. latifolia very likely arrived in Britain & Ireland along with Neolithic arable farmers, and probably it was then most common in S England (Baker 1947; Godwin 1975; Clapham et al. 1987).

Fermanagh occurrence

White Campion has only been seen once in Fermanagh – at the municipal rubbish tip just outside Enniskillen by Meikle and his co-workers in 1947.

Irish occurrence

The Cen Cat Fl Ir 2 lists S. latifolia (as S. alba) occurring in 28 of the 40 Irish VCs, and for quite some time this weed of cultivated land, or casual of waste ground, dockyards and roadsides has been regarded as a probable introduction in Ireland. In her Cat Alien Pl Ir, Reynolds reckoned White Campion is fairly common across the island in disturbed and sandy ground, eg on roadsides and especially near ports. She points out that Praeger and others in the late 19th century realised that it was being occasionally imported with foreign grain.

Reynolds (Cat Alien Pl Ir) may be over-estimating the Irish presence of S. latifolia, at least in a N Ireland (NI) context, since it is really only a casual colonist here (Flora of Lough Neagh; FNEI 3). Apart from the solitary Fermanagh record the NI Vascular Plant Database contains 40 records for the other five VCs in NI. Almost exclusively, these date from 1976 onwards, so we assume earlier records have been neglected. Computerisation of early NI plant records is not yet complete. The Flora of Co Tyrone lists eleven recent records, all of them post-1981 (McNeill 2010). Nevertheless, despite the incomplete NI picture the number of records does suggest that seed of S. latifolia is still being occasionally imported, and the plant appears sporadically for short periods in suitably open ground.

British status and occurrence

Previously in Britain, botanists traditionally assumed S. latifoia was an indigenous species. Stace (1997) vainly clung to this belief, long after evidence otherwise was clearly presented by Baker (1947). Received opinion has been recently revised (Preston et al. 2004), and S. latifolia is now recognised as an early introduction (ie an archaeophyte) in both Britain & Ireland. White Campion has always been much more scarce and local in Ireland in comparison with Britain. It remains fairly common and widespread in Britain today, although with a definite eastern tendency in its distribution, and the distribution becomes more coastal northwards (Preston et al. 2002). The New Atlas map suggests there have been losses of this species at the western margins of its British & Irish distribution.

Locally in Fermanagh, we can attribute loss of weeds like this to the decline in arable agriculture to near absence. Elsewhere in Britain & Ireland, the decline in arable weeds is certainly due to changes in agricultural practices, including the use of cleaner crop seed, widespread spraying of herbicides and the use of artificial fertilisers and slurry to increase crop productivity. There have been reports, however, that S. latifolia is resistant to commonly used herbicides, such as 2,4-D and 2,4,5-T (Salisbury 1964; McNeill 1977).

The findings of the recent 'Local Change' re-survey of BSBI 'Monitoring Scheme' hexads in Britain, emphasises the fact that S. latifolia is struggling to maintain its distribution, especially in the more pastoral west of the island (Braithwaite et al. 2006).

European and world occurrence

S. latifolia is widespread as a native weed throughout Europe northwards to 68°N in Scandinavia, ranging east to Mongolia and SE Siberia and south to N Africa (Jalas & Suominen 1986, Map 1183). It also occurs as a neophyte or archaeophyte introduction in more northern areas of Scandinavia, Iceland, Greenland, Ireland, Great Britain, parts of India, Australia, Tasmania and New Zealand. The present distribution is amphi-atlantic and almost circumpolar (Hultén & Fries 1986, Map 793). Preston & Hill (1997) classified it as Eurosiberian southern-temperate, but widely introduced. In Scandinavia, it is believed to have been introduced in the 19th century along with ley seed and cereals, and perhaps also with ship ballast and along with foreign troops (Jonsell et al. 2001).

In North America, White Campion was introduced from Europe sometime in the early 19th century probably as a crop seed contaminant. In Canada, it remains an important weed of field crops such as alfalfa (Medicago sativa), clover (Trifolium spp.) and small grain and legume grain-forage rotation crops. In 1965, S. latifolia was reported as one of the five worst weeds in pastures and hayfields in six states from New Hampshire and Connecticut to Minnesota, and at that time infestation was still increasing (McNeill 1977).

Names

The origin of genus name 'Silene' is obscure (Gilbert-Carter 1964) but might possibly be derived from the Greek 'sialon' meaning 'saliva', referring to the gummy exude from the stem which wards off insects (Johnson & Smith 1946). Another suggestion is that 'Silene' is Theophrastus' name for another plant (Viscaria), a different Catchfly (Gledhill 1985; Stearn 1992). The Latin species epithet 'latifolia' translates as 'broad-leaved'.

Threats

In Britain & Ireland, cleaner crop seed, the increased use of herbicides and a gradual shift away from arable agriculture are probably jointly responsible for the decline of this species.

Silene dioica (L.) Clairv., Red Campion

European Boreo-temperate

1953; MCMD (1957, Typescript Flora); Belcoo, Lough Macnean

Throughout the year.

Growth form and preferred habitats

A very attractive and conspicuous plant when bearing its red or pink, few-flowered cymes, this fairly short-lived perennial is locally uncommon, occasional and rarely abundant in semi-shaded or more open, north-facing ecological conditions, mainly in a variety of semi-natural, sometimes only intermittently available habitats (Salisbury 1942). The softly pubescent, broad, basal, wintergreen leaves are quite distinctive and the species can therefore be easily recognised throughout the year.

S. dioica is most regularly found in sheltered, moist, open situations at the base of cliffs, or forming loose patches in woodland clearings, or along paths within and on the margins of woods, or on hedged river banks, stream sides or ditches, or in tall-herb roadside banks and verges. S. dioica requires damper soils than S. latifolia (White Campion) does, and in comparison it is much less, or not at all, drought resistant.

While Red Campion tolerates a broad range of substrate conditions, it prefers fertile, nitrogen-rich, moderately acid to neutral soils in sites where the vigour of competing species is limited either by shade, or by occasional disturbance (eg slippage on unstable slopes or temporary flooding). It tends to be less prevalent on lime or base-rich soils, except when these are in more open, rocky, steep sites, or in deep, narrow limestone crevices (called grykes), that protect the plant from grazing pressure by their sheer inaccessibility (Clapham et al. 1987; Grime et al. 1988). Like the closely related S. latifolia, Red Campion is not fully frost hardy (although rarely killed by frost in Britain & Ireland), and it also avoids waterlogged and strongly acidic substrates (Baker 1947; Grime et al. 1988).

S. dioica has a taproot that grows horizontally near the surface of the soil for a distance before turning down vertically, but it never reaches the 40 cm soil depths that S. alba roots achieve. Red Campion performs best in light shade and it fails to flower and seed when growing under very heavy leaf canopy. Being essentially a woodland mesophyte, it cannot compete in very exposed, windy conditions (Baker 1947).

In the Sheffield area, Grime et al. (1988) concluded that S. dioica showed a, "pronounced inability to exploit conditions of extreme stress or disturbance", and the life strategy of the established plant was described as 'C-S-R', ie intermediate between the primary strategies of Competitor, Stress-tolerator and Ruderal. Species of similar ecological behaviour in this respect include Hypochaeris radicata (Cat's-ear) and Rumex acetosa (Common Sorrel).

Variation

Genetically, this is a very variable species both within and between populations. The range of plant variation is related to both geographic location and habitat environment and several named varieties exist (Jonsell et al. 2001). Thick-leaved coastal populations in Shetland were once considered sufficiently different to constitute a separate variety (var. zetlandicum Compton), or even a subspecies. Dwarf variants occur on mountains, exposed rocks and sand dunes (Tutin et al. 1993). However, subsequent studies in Britain and Europe concluded that S. dioica variation consists of local, weakly differentiated races that intergrade at their geographic margins, and thus there is no point in recognising the variation taxonomically (Prentice 1980).

Variation within the Silene vulgaris aggregate and in related species including S. latifolia and S. dioica has occasioned numerous changes in classification and nomenclature over the years. Silene dioica has been in two other genera, namely Lychnis and Melandrium.

Hybrids

A fully fertile hybrid with S. latifolia occurs wherever they overlap.

Fermanagh occurrence

For some reason, probably explained by the aforementioned species preferences, locally S. dioica is most frequently met in Fermanagh around the Boho region in the mid-SW of the vice-county, but it is recorded in a total of 44 of our tetrads, thinly scattered around the wooded shore areas of Lower Lough Erne, and even more widely and sparsely elsewhere in the county.

Reproduction, vegetative and flowering

Red Campion tends to have a loose rhizome system or branching secondary roots near the soil surface, which allows a minor degree of vegetative spread (Dalpra 1965). Apart from this, S. dioica reproduction and dispersal is entirely achieved by seed. As the scientific name indicates, Red Campion is a dioecious species, and in this instance, the frequency of male plants to some extent predominates over females. Male plants produce more leaves and flowers than females (Cox 1981; Kay & Stevens 1986). Although germination and growth can be quite rapid in a suitable environment, up to 80% of plants do not flower until their second season of growth (Baker 1947).

The number of flowers per plant is seldom large, many bearing less than 20. The flowering season runs from April to September, or until the first frost. In females, the calyx is urn-shaped and inflated, becoming rounded in fruit, while in males it is more cylindrical or campanulate. Petals are red or bright pink, rarely white and the flowers are (18)20-25(30) mm in diameter. The flowers are open in daytime, and while they produce no perfume, they attract mainly bumble-bees and butterflies as pollinators. The female flowers are subject to the same attacks as S. latifolia by egg-laying moths of the genus Harmodia. The insect larvae parasitize the developing ovules, causing a major reduction in seed production (Baker 1947).

Seed production, germination and seed predation

Seed production is extremely variable, being dependent upon local environment and individual plant size and vigour, a phenotypic reflection of the former factor. The number of seed per capsule varies from 10-233 (Baker 1947), while Salisbury (1942) found the range in his samples in S England stretched from 41-288, with a mean of 215 seeds per capsule. The distance of seed dispersal by wind (censer mechanism) is rarely more than 2.5 m, and germination takes place in any month except August, but it chiefly occurs in spring (Knight 1978 a, b).

Fungal pathogens, such as Smut, Rust and Damping-off, limit both flowering success and seedling establishment. In a damp, humid oceanic climate like ours, these combined stresses are so forceful, they effectively tip the balance against S. dioica survival when indigenous populations are low to begin with (Baker 1947).

Dormant seed survival

Dormant seed persistence in the soil is also extremely variable. The survey of seed survival in NW European soils lists 21 estimates: seven transient, five short-term persistent, two long-term, and seven uncommitted in this respect (Thompson et al. 1997).

Fossil history

Seed of S. dioica have been found in early glacial and interglacial periods and in all zones of the Late Weichselian, and many of the current Flandrian interglacial. The presence of this species in two glacial and two interglacial stages contrasts strongly with the absence of S. latifolia. The present day ecology of S. dioica and its distribution so far north in Europe, suggests it could be a periglacial survivor, having perhaps been present continuously in or near these isles (Godwin 1975).

Irish occurrence

The New Atlas hexad map indicates that S. dioica is considerably more widely (and perhaps more frequently) recorded in Northern Ireland than in the Republic of Ireland, where it is only very thinly and widely scattered (Preston et al. 2002). However, even within N Ireland, Red Campion is not evenly widespread, but rather it is absent from much of Cos Armagh and Down (H37 & H38), a distribution feature which yet remains to be explained (NI Flora Website 2006).

British occurrence

S. dioica is locally abundant throughout almost all of lowland Britain, but rare in the dry sandy Breckland of East Anglia and the intensively farmed area of Cambridgeshire and its immediate surrounds.

Overall, S. dioica has a very curious distribution in Britain and Ireland, the New Atlas hectad map looking at first glance, as if the species had a decidedly United Kingdom (UK) flavour to it. In many of the 34 vice-counties in the Republic of Ireland, no resident member of the BSBI recording community exists and the designated BSBI Recorder in numerous VCs may live a hundred or more kms outside its boundaries. The number of recording hours and coverage they can achieve is hugely reduced in comparison to British VCs. Thus the representation of species distribution we see in the published New Atlas maps is necessarily an artefact, since the data over the whole area involved are not uniform in quality and are not comparing like with like.

The Balkans as a possible species origin

The centre of origin of S. dioica remains unknown, but it most probably lies in the Balkan Peninsula, or nearby. A study of S. dioica and its close relatives, S. latifolia and Melandrium nemorale, suggests that the latter, a woodland plant of Rumania, Bulgaria and Greece, has characters very similar to those of both S. dioica and S. latifolia. M. nemorale may resemble the supposed or expected ancestor of all three species. The geographical distribution of M. nemorale also appears to represent the point of divergence of these three species and of all of their recognised subspecies (Dalpra 1965). The Balkan region represents the area where the C European and Mediterranean climatic regimes meet. Its mountains and valleys provide an environment where climate varies greatly over a relative small area. Species mingle here in unusual proximity, and ecotypes can readily arise and diverge.

The Balkans is also one of several southern refugia areas to which European plant life retreated during recent ice ages/glacial stages. Another important factor, is that change is particularly encouraged when man disturbs vegetation and creates new, artificial habitats, some of them associated with the introduction of tillage and grazing agriculture. Agriculture has favoured the spread of S. latifolia, which thrives as a crop weed, while the destruction of woodland to create fields has been to the detriment of S. dioica populations. S. dioica has fewer weedy characteristics, and appears much less able to compete with cereal roots than S. latifolia (Dalpra 1965).

European and world occurrence

S. dioica occurs throughout most of Europe northwards to the Faeroes and Spitsbergen, but it is absent from parts of the Mediterranean, including all of the islands. Although indigenous in Europe, the species is very closely associated with man (ie it is anthropochorous). In many lowland areas of Scandinavia, it occurs entirely in man-made habitats and is considered a recent immigrant, imported with ley and hay seed. This is especially so in Finland, where S. dioica is considered native only in coastal sites (Jalas & Suominen 1986, Map 1189). Further north in Scandinavia, S. dioica becomes rare and casual (Jonsell et al. 2001). The distribution extends eastwards to C Asia as far as Altai, and it is also present in N Africa and Greenland. In Iceland, S. dioica is an established garden escape. It is introduced in eastern N America and in New Zealand where it is recognised as a garden escape (Hultén & Fries 1986, Map 795; Webb et al. 1988, p. 499).

Uses

The flowers are brightly coloured and the plant very easily cultivated making it a popular decorative garden subject. As many as eight garden varieties are listed by Griffiths (1994).

Names

The origin of genus name 'Silene' is obscure (Gilbert-Carter 1964) but might possibly be derived from the Greek 'sialon' meaning 'saliva', referring to the gummy exude from the stem which wards off insects (Johnson & Smith 1946). Another suggestion is that 'Silene' is Theophrastus' name for another plant (Viscaria), a different Catchfly (Gledhill 1985; Stearn 1992). The Latinised specific epithet 'dioica' in Greek means 'two houses', or 'double houses', a reference to the separate plants, each with flowers of one sex only.

'Red Campion' has a very long list of English common names, Grigson (1987) listing no fewer than 63 variants. The names have snake, devil, goblin and 'death if picked' folklore connotations. A number of the names are shared with two other May-flowering, woodland species, Bluebells (Hyacinthoides non-scripta) and the Early-purple Orchid (Orchis mascula), eg 'Cuckoo-flower'. 'Campion', itself is a 16th century Elizabethan book name that has never been convincingly explained. It remains a bit of a mystery. It first appeared in 1576 and was soon taken up by poets as well as botanists. 'Campion' may be equal to, or be another version of 'champion', ie a champion flower of the summer garden (Grigson 1974).

Threats

None.