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Cerastium arvense L., Field Mouse-ear

Account Summary

Native, very rare, but probably a mis-identification. Circumpolar boreo-temperate.

1 June 1995; EHS Habitat Survey Team; Moneendogue ASSI.

Growth form and preferred habitats

This very variable, large-flowered, rhizomatous, loose mat-forming perennial Chickweed is more or less restricted to dry, well-drained, calcareous to slightly acid light sandy or gravelly soils, often in open or semi-closed vegetation in sunny habitats that have been either created or strongly influenced by man. The range of habitats includes short, permanent pastures, margins of arable fields, sand-pits, wayside verges, roadside banks and waste ground. Less frequently, near the coast C. arvense can occur on sand or sandy gravel in dune grassland. The upper portion of the plant and the inflorescence are more or less densely covered with short hairs (<1mm), some hairs glandular (but not sticky). Leaves are linear-lanceolate, acute, hairless or sparsely hairy (Garrard & Streeter 1983; Stace 2010).

Variation

In Europe, six geographical subspecies have been described, of which only subsp. arvense occurs throughout the species range, including Britain & Ireland (Tutin et al. 1964). Varieties have also been named in relation to characters such as the degree of plant hairiness and leaf shape. In N America, C. arvense displays a high degree of phenotypic plasticity which is undoubtedly adaptive, and which helps explain the broad ecological tolerance and the degree of taxonomic variation observed within the species across its wide geographical range (Wagstaff & Taylor 1988).

Sexual reproduction

Flowering takes place from May to August. The erect inflorescence is few-flowered (3-7), with pure white flowers 12-20 mm in diameter, bilobed petals about twice as long as sepals, and a superior ovary with four or five styles. The flowers are protandrous, nectar is partly concealed and pollination is by small bees and flies (Proctor & Yeo 1973). The capsule is cylindrical and straight, 6-8 mm, slightly longer than the sepals. It opens by splitting at the apex to form ten teeth that help release the seed.

Seed production and survival

The dark red-brown seeds are flattened asymmetrically, often wider than long, with acute, narrow tubercules. In Finland and Scandinavia, where C. arvense is a 19th century introduction, seed set is often low or absent, possibly due to high levels of self-incompatibility, plus the occurrence of purely female clones (Jonsell et al. 2001). On the other hand, elsewhere in its wide geographical and altitudinal range, C. arvense is regarded as an obligate outcrosser (Wagstaff & Taylor 1988).

Survival in the soil seed bank is listed as either transient or short-term persistent, meaning continuing presence for up to five years (Thompson et al. 1997).

Vegetative reproduction

The plant has a profusely branching rhizome and the lower leafy stems are procumbent and readily root at their internodes, thus helping to spread the plant and form loose, sprawling clonal mats, or tighter, denser, upright clumps.

Fossil record

The distinctive seeds of C. arvense have been found in all sub-stages of the Weichselian Ice Age and all zones of the Late Weichselian. However, there is a total absence of any fossil seed in the current interglacial (Flandrian) record, which certainly appears significant. Godwin (1975, p. 147) drew attention to Hultén's description of the plant (Hultén & Fries, 1986) as belonging to the category of circumpolar species strongly spread by culture (see European and world occurrence below).

Fermanagh occurrence

There are just two records of C. arvense in the Fermanagh Flora Database, both of which were made by members of an EHS Habitat Survey Team in separate sites in the far NW of Fermanagh in June 1995. The details of the first record are given above and the second was made on 9 June 1995 at Drumlisaleen meadow.

Irish occurrence

C. arvense is a very rare and local plant in the N of Ireland, usually occurring on coastal sand banks and dunes. It has been recorded in one or two sites in Cos Down and Antrim (H38 & H39), and until the 1940s and 1950s, also at two inland sites on the shores of Lough Neagh (FNEI 3). John Harron (Flora of Lough Neagh) did not manage to refind it in his thorough floral survey of Lough Neagh. Otherwise, C. arvense in Ireland is restricted to dry, calcareous to somewhat acidic sandy or gravelly soils near the coast mid-way along the E & W coasts. It is locally frequent in the Burren, Co Clare (H9) and near Galway city, but only rare and scattered along the Co Dublin coast (H21) (Flora of Connemara and the Burren; Flora of Co Dublin).

While it would not be impossible to find C. arvense in dry limestone grassland in Fermanagh, we really ought to reject the two 1995 records without supporting vouchers and until such confirmation is provided we have to regard these as possible mis-identifications. If this species had ever been recorded in Cos Donegal, Sligo or Leitrim (H34 & H35, H28 and H29) we would look on this as a mere extension of its range, but this is not the case. Having said all that, with its relatively large white flowers it is difficult to imagine which other related species of dry limestone grassland might have been mistakenly identified as C. arvense. The only candidate is Stellaria holostea (Greater Stitchwort), and it is hard to conceive that one or more members of an experienced EHS Habitat Survey Team could mistake such a common plant for anything else. Of course having no vouchers we have no idea of the condition of the two plant specimens in question, but what is clear is that the field botanists who listed the C. arvense did not appreciate that it was a significant find in an Irish context.

Unfortunately in these situations quite often the survey workers employed by EHS fail to collect a voucher. In other Fermanagh situations, where these workers found a questionable plant, the EHS field card is sometimes marked with an asterisk or a comment, indicating the recorder knew or felt the record might be of special significance. The absence of this type of recognition suggests two possibilities: either the plant wasn't properly examined, or perhaps an imported British botanist was involved who expected to find C. arvense in the vegetation being surveyed.

British occurrence and decline

In Britain, C. arvense is widespread, but with a distinct eastern tendency in its distribution. It is certainly not restricted to coastal situations, but is found across the country on dry pastures, roadsides, wayside banks and field margins (P.S. Lusby, in: Preston et al. 2002).

Within the area of calcareous soils prevalent in E England where the species is principally, but infrequently recorded, the presence of C. arvense appears to be declining. Particularly at the margins of its range, recording indicates there are losses that probably reflect cultural eutrophication seeping in from surrounding 'improved' grasslands, together with physical destruction of the dry, often rocky grassland fragments in which it is mainly found (Braithwaite et al. 2006).

European and world occurrence

Circumpolar boreo-temperate, native in C & W Europe, although not indigenous in NW Europe including Fennoskandia. It is indigenous also in Mongolia, Japan, China, N & S America and Greenland. In the former USSR, the species is distributed in Arctic regions, in the European part, in the Caucasus, W & E Siberia. It is also native in parts of the Far East and C Asia. As Hultén & Fries (1986) point out, both within and beyond the original native area of the species, which it is impossible to define exactly, the species sensu stricto and other taxa have been spread considerably by man, eg to S Africa and New Zealand (Hultén & Fries 1986, Map 741).

Names

The genus name 'Cerastium' is from the Greek 'keras' or 'kĕrastēs' meaning a horn or horned respectively, from the fact that some species have curved seed capsules resembling horns as they emerge from the calyx (Johnson & Smith 1946; Stearn 1992). The Latin specific epithet 'arvense' means 'growing on arable land' from 'arval', 'arable land' (Gilbert-Carter 1964). The English common name 'Field Mouse-ear' is a book name, but see the Names section of my Cerastium fontanum species account on this website for more consideration of the name origin.

Threats

C. arvense is regarded as near threatened on the 2005 Red List of plant in the UK, which includes N Ireland and the other three British subdivisions (NBN website, viewed 23 January 2018).

Cerastium fontanum Baumg. (C. holosteoides Fr. = C. vulgatum L.), Common Mouse-ear

Native, very common and widespread. Eurosiberian boreo-temperate, but so widely naturalised as to have become circumpolar boreo-temperate.

1881; Stewart, S.A.; Co Fermanagh.

Throughout the year.

Growth form and preferred habitats

This very variable, often densely hairy, straggly to loosely tufted, or low creeping, mat-forming, wintergreen perennial (or sometimes annual) weed, grows in a tremendous variety of both natural and man-made, moderately fertile (mesotrophic) habitats. They can vary from moist to relatively dry, unshaded grasslands to numerous types of more or less disturbed ground throughout Britain & Ireland (New Atlas). Typical growing conditions are found mainly but not exclusively in lowland areas, and include moist meadows, pastures, lawns, lake shores, rock outcrops and moderately disturbed ground on roadsides, quarries and rough wayside areas. It does occur, but much less frequently, on soggy, boggy ground, both acidic and calcareous, and in also in more shaded situations. C. fontanum can also appear in coastal situations on fixed sand dunes and on shingle. It can also invade a range of artificial habitats, including cultivated ground, waysides, walls and the base of fences.

C. fontanum can be distinguished from the other small-flowered Cerastium species by the absence of glandular hairs on the sepals, the sepal hairs not overtopping the sepal apex, and the five styles being 1.5-2 mm long (Webb et al. 1988).

Fermanagh occurrence

In Fermanagh, C. fontanum is recorded in 482 tetrads, 91.3% of those in the VC. It is absent, however, from three situations: aquatic habitats, strongly acidic bogs and deep or dark, evergreen shade. In the Fermanagh Flora Database, it ranks 40th in terms of recording frequency, falling between Calluna vulgaris (Heather) and Dryopteris dilatata (Broad Buckler-fern). On the other hand, when its presence is measured in terms of tetrad frequency, C. fontanum lies in 12th place in the county and its neighbours on the listing are Hedera helix (Common Ivy) and Taraxacum officinale (Dandelion).

This difference in ranking indicates (albeit in a rather subjective and crude manner) the considerable extent to which semi-natural habitats in Fermanagh were surveyed in detail for their conservation potential, while comparatively few man-hours have been devoted to disturbed, artificial situations. This is very probably always the case with the many local flora surveys that have been carried out over the years. At least we expect this to be the situation in rural VCs, if not in those with a high proportion of urban areas and associated disturbed, artificial habitats.

Variation

On a world basis, C. fontanum has a very wide distribution and ecological range and is often selfed (ie autogamous). This gives rise to marked polymorphism to such an extent that four subspecies are recognised in Europe (Tutin et al. 1993). Three of the European subspecies are recognised as occurring in Britain & Ireland, although one of them, subsp. holosteoides (Fr.) Salman, is considered a variety in Flora Europaea (Clapham et al. 1987). Two of the European subspecies are recognised in Ireland – the very common form, subsp. vulgare (Hartm.) Greuter & Burdet, and the rarer subsp. holosteoides. The latter form is always associated with rivers, where it grows on grassy riverbanks, marshy flood-plain meadows, or just upstream of the sections of rivers that are under tidal influence. Unfortunately, these two more widespread subspecies intergrade, and at some sites only intermediates are known (M.B. Wyse Jackson, in: Rich & Jermy 1998).

The third taxon, subsp. scoticum Jalas & P.D. Sell, is regarded as a Scottish endemic. Stace (2010) suggested that all these taxa might be better placed in just one subspecies. On the other hand, Sell & Murrell (2018) divide the variation into just two subspecies, subsp. scoticum and subsp. vulgare, the latter subdivided into four varieties (var. glandulosum (Boenn.) P.D. Sell, var. serpentini Novák, var. lucens (Druce) P.D. Sell and var. vulgare (Hartm.) M.B. Wyse Jacks. The previous species or subsp. holosteoides is subdivided and relocated mainly in var. lucens (Sell & Murrell 2018).

Both of the subspecies previously listed for Ireland have been very rarely recorded in Fermanagh, but the vast majority of records of this common weed have not been discriminated at subspecific level in the county.

Sexual Reproduction

In some situations, Common Mouse-ear can show the rapid relative growth rate typical of weedy ruderal species, and under greenhouse conditions it can flower within nine weeks of germination (Peterson 1969). Flowering usually takes place between April and September. Flowering shoots are more erect than vegetative ones, and are short-lived. The inflorescence typically bears around 20 perfect, hermaphrodite flowers. The flowers have five petals, bilobed to about mid-way (ie emarginate), shorter than, or up to 1.3 times as long as the sepals. The flowers are protandrous and are visited mainly by flies. However, they are self-compatible and set seed even if insects fail to pollinate them (Clapham et al. 1987). A normal-sized plant produces around 6,500 seeds (Salisbury 1964, p. 159).

Seed dispersal and survival

The curved capsules, 7-18 mm in length, open by splitting at the top to form ten teeth. The brown seeds are rounded triangular in outline and are decorated with tubercles or low ridges. Seeds are presumably dispersed mainly by wind, but they are also carried in mud by man (ie anthropochorus, literally 'carried by man' as a primary dispersal agent), and other animals. Previously, before efficient industrial seed cleaning, seed of C. fontanum was incidentally transported worldwide mixed with commercial grain (Ridley 1930; Peterson 1969). Seed can survive dormant in the soil for over 40 years.

Vegetative reproduction

While individual flowering stems of C. fontanum may be short-lived, adventitious rooting of horizontal/decumbent lower stems and growth of a creeping rootstock constitute vegetative propagation, enabling the formation of persistent, dense clonal mats and lateral spread of the species in permanent grasslands (Clapham et al. 1987; Grime et al. 1988).

Competition and disturbance

Being an essentially creeping, mat-forming perennial or annual, C. fontanum is not able to compete with more aggressive, taller species. It therefore tends to avoid such competition, tolerating habitats where it experiences moderate to severe levels of disturbance in order to survive in the long-term (Grime et al. 1988). Jonsell et al. (2001) mention short, ascending or erect rhizomes (ie swollen stems), in some forms of the species, which may also feature in enabling vegetative propagation. In pastures, C. fontanum can cope with moderate levels of grazing and trampling by cattle, and in lawns it tolerates mowing very well and can persist under such a regime for long periods. This degree of survival ability is largely due to the plant's powers of reproduction and regeneration, which are governed by the level of soil fertility present.

Fossil history

Fossil seed of C. fontanum (listed as C. holosteoides Fr.), has been found in Britain and Ireland in several interglacials from sub-stage II of the Hoxnian onwards. Four records in the current Flandrian interglacial are associated with agriculture or settlement and date from 2390 BP through to the medieval period (4th to 9th century AD). Godwin (1975) comments that it appears to have thrived in periglacial conditions, surviving in open situations naturally through interglacials and to have expanded in response to later human clearances.

British and Irish occurrence

C. fontanum, in the broad sense, is very common and widespread throughout the whole of both Britain and Ireland, including offshore islands. The subspecies are not widely recorded and their distribution is not yet clear.

European and world occurrence

This is a Eurosiberian boreo-temperate species, believed to have originated in Europe and W Asia. However, it has been extremely widely distributed as a weed of cultivation, and has become circumpolar boreo-temperate and almost cosmopolitan (Hultén & Fries 1986, Map 747).

Names

The genus name 'Cerastium' is from the Greek 'keras' or 'kĕrastēs' meaning a horn or horned respectively, from the fact that some species have curved seed capsules resembling horns as they emerge from the calyx (Johnson & Smith 1946; Stearn 1992). The Latin specific epithet 'fontanum' is from 'fons, fontis' meaning a spring or fountain, a reference to damp habitats (Gilbert-Carter 1964).

C. fontanum (as C. trivale Link.) is listed with three English common names, 'Chickweed', 'Mouse-ear Chick-weed' and 'Mouse-ear' by Britten & Holland (1886), who regard it as a general book-name for any form of Cerastium, but especially linked with this species. 'Chickweed' is of course shared with Stellaria media and many other small plants of similar habit, and 'Mouse Ear' is likewise shared with Hieraceum pilosella L., in both instances the name is presumably given on account of the shape and hairiness of the leaves which resemble a mouse's ear. The name 'Mouse-ear' was first applied to both these species by Henry Lyte (1578) in his translation made from l'Écluse's French version of Dodoens' Crŭÿdeboeck of 1554, entitled A Niewe Herball.

Threats

None.