Papaver rhoeas L., Common Poppy

Account Summary

Growth form and preferred habitats

Common Poppy is a summer annual which in Britain and Ireland has always been tightly restricted to open, disturbed, artificial habitats. Before the advent of selective herbicides, which over the last 30 years or so have almost exterminated the species from farmland, the distinctive red poppy flower was closely associated with fallow field margins around arable land, especially where the ground was under cereal cultivation. Nowadays, P. rhoeas is confined to other unsprayed forms of open or disturbed, artificial habitats, such as waysides, quarries, building sites, soil heaps, waste land and on walls (McNaughton & Harper 1964; Grime et al. 1988). The soil which suits Common Poppy best is a fairly light, warm, sandy and free draining one with a pH between 6 and 8. The ideal soil is of medium fertility and moderate to rich in calcium or other bases (Sinker et al. 1985).

Status as an ancient introduction

This ruderal annual species has an interesting and much studied biology, ecology and history. Along with numerous other arable weeds, populations of which were once considered stable and resilient, P. rhoeas populations have rapidly become impoverished and in Co Fermanagh the species has declined to rarity. Thus Papaver rhoeas has become of greater interest and concern to some conservation-minded people, while other botanists consider it a mere accidental contaminant of crop seed, albeit that of migrant Neolithic or Bronze Age farmers, 5500-2500 B.P. (Grieg 1988; Kadereit 1990; Wilson 1992). Plants of this origin in the British Isles have recently and belatedly (see eg Stace 1997) been recognised as 'archaeophytes', ie ancient, pre-1500 AD 'synanthropic' introductions (ie associated with man). A total of 149 such species are now acknowledged in the flora of Britain & Ireland, including P. rhoeas, by the editors of the New Atlas (Preston et al. 2002), and this figure is likely to grow.

Unlike other archaeophyte arable weeds, for example, Scandix pecten-veneris (Shepherd's-needle) and Centaurea cyanus (Cornflower), P. rhoeas is not yet a rare plant on an entire British Isles basis, but it has already become a rare casual in Fermanagh, there being a total of only twelve records in the Flora Database, three of which are derived from sown seed mixtures (see details below). On account of its local rarity, the 'Common Poppy' is given more consideration here than might otherwise be considered appropriate. After all, as Wilson (1992) reminds us, "weeds have accompanied these cultivated annual grasses [he is here referring to cereals] since their wild days, and in a very real sense, the history of weeds is the history of mankind".

Geographical and cultural origin

Along with three other poppies which are also archaeophytes (ie P. dubium (Long-headed Poppy), P. lecoquii (Yellow-juiced Poppy) and P. argemone (Prickly Poppy)), Common Poppy probably originated in SE Europe. The fossil history of P. rhoeas stretches back to middle and late Neolithic times in C Europe, and to the late Bronze Age in the British Isles (Godwin 1975). Kadereit (1990) examined the distributions of these poppies and compared them with their nearest 'wild' (ie non-synanthropic) relatives. His study suggests that P. rhoeas originated in the eastern coastline of the Mediterranean, where it appears to have differentiated from one of three close relatives, or from a hybrid between them (although without involving any change in chromosome number). It probably did so only after disturbed and cultivated ground in sufficient extent was provided by man as a habitat. Thus it seems possible that not only was P. rhoeas widely distributed by man with his cereals, but that as a taxonomic entity, the species may also be of synanthropic origin (Kadereit 1990).

P. rhoeas is chiefly a summer annual, a lifestyle which in itself might suggest a circum-Mediterranean origin, although in mild areas of the British Isles or in exceptional winters with little severe frost, autumn germinated seedlings may sometimes survive (Greig 1988). Summer annuals like P. rhoeas are capable of maturing and flowering after a short spurt of rapid vegetative growth in the spring, or failing this, flowering even when the plant is very small. Having this short, or relatively short, growing season, poppy plants are certainly favoured by our mild, damp oceanic climate, rather than a hot, dry continental one, which curtails their growth and development during the summer months (Greig 1988).

Fermanagh occurrence

For this weedy species, there have only ever been a total of twelve records spread over seven Fermanagh tetrads, four of which have post-1975 records. Until RHN discovered an individual plant flowering on roadside waste ground near Gublusk Bay, Lower Lough Erne in September 2003, Common Poppy had not been seen 'wild' anywhere in the county since 1950. However, there were two instances of it being deliberately sown in so-called 'wild-flower' seed mixtures in 1996 and 2003 in garden and in roadside settings. Since this very colourful and conspicuous species is well known to be capable of persisting buried and dormant in the soil seed bank for at least 80 years, and probably for more than a century (Salisbury 1964), it is always worth looking out for it on any freshly cultivated or recently disturbed patch of ground.

Before RHN, the current author and our contemporary botanical associates began recording in the early- to mid-1970s, agricultural weeds and plant introductions of any type or origin tended to be completely ignored by previous field workers in Fermanagh. Apparently earlier recorders considered them unimportant, or at least a waste of time in comparison with the need to record more obviously significant native plants, ie definite or perceived native species.

The details of the other eleven existing Fermanagh records are: football club car park, Newtownbutler, 1930-40, R.C. Faris & J.M. Cole; old railway station, Florencecourt, 1950, Meikle et al.; planted wild flower seed mix in garden near Levally House, 1 km SE of Roosky, October 1996 & October 1997, RHN; roadside waste ground, Gublusk Bay, Lower Lough Erne, September 2003, RHN; sown wild flower mix, at road junction of Sligo and Ballinaleck Roads, Enniskillen, September 2003, RHN; one plant on Queen Elizabeth Road, Enniskillen, 17 July 2006, RHN; one plant in a garden at Goblusk Bay, Lower Lough Erne, 14 August 2009, RHN; Clabby village, 26 June 2011, RHN; and Riversdale Forest, 29 June 2011, RHN.

Factors limiting distribution

Unsuitable soils

Apart from coastal situations, warm, sandy soils with the particular micro-environment that suits this poppy are scarce in the north and west of Ireland, in Scotland and on higher ground anywhere throughout the British Isles. Most of these geographical areas combine a geological structure that produces strongly acidic, high-silica soils that are frequently covered with a layer of nearly impervious glacial till of similar rock mineral origin and chemistry. In addition, lying close to the Atlantic seaboard, many soils in the more westerly parts of Britain and Ireland have suffered high levels of precipitation throughout the entire 11,000 years of the post-glacial period. The subsequent percolation of rainwater has resulted in soil mineral leaching, acidification, gleying and podsolisation, sometimes leading to the formation of huge swathes of organic blanket bog peat. The resultant lack of suitable soils makes it unsurprising that P. rhoeas is a scarce or casual species in the most northerly and western parts of Britain and Ireland.

Decline of tillage

The scarcity of this previously common weedy species in the north and west of Britain and Ireland was produced and perpetuated when the low intensity arable agriculture that previously allowed the Common Poppy's annual seed population renewal, gradually became increasingly uneconomical. Arable cultivation, especially of cereals, continued to decline further after the Second World War, eventually reaching a very low level, or near extinction.

A measure of disturbance

All poppy species, including P. rhoeas, require open, sunny habitat conditions, with bare patches of soil for seedling establishment. Thus poppies are rarely found in closed, grazed turf. If they are, then disturbance such as grazing and trampling must be sufficient to minimise competition from neighbouring plants, and provide sufficient openings in the soil surface for this ruderal species to germinate and establish. At the same time, the foraging disturbance must be limited to allow the species sufficient time to grow, flower and set seed successfully.

Toxicity

In order to limit grazing pressure, P.rhoeas contains a number of toxic or narcotic alkaloids, eg rhoeadine and rhoeagenine, which give off an unpleasant odour and make the plant unpalatable or sickening to browsing animals. There are no recent cases of animals being poisoned by P. rhoeas in the British Isles (Grime et al. 1988; Cooper & Johnson 1998).

Phenotypic variation and reproductive capacity

All Papaver species in Britain and Ireland are very plastic in their phenotypic response to growing conditions. They are particularly sensitive to shading, nutrient deficiencies, lack of water, or an excess of it, and interference from non-related species. All of or any of these variables can drastically reduce the poppies growth and reproductive capacity. P. rhoeas is exceptionally plastic in these respects, and McNaughton & Harper (1964) described finding depauperate plants in soils of very low fertility that were only 5 cm tall, bearing a single capsule containing four or five seeds. At the other extreme, under favourable conditions, an isolated individual might bear 300 to 400 large capsules, each containing more than 1,000 seeds (McNaughton & Harper 1964; Harper 1966).

An unusual feature of P. rhoeas variation is that flower size is also among the characters which are very plastic. Nutrient or water deficiency results in reduction of petal size, number of stamens, ovary locules and seeds. When species are as variable as poppies are, mean figures for properties such as seeds/capsule, or per plant unfortunately become rather meaningless, so I will refrain from quoting any such figures (Salisbury 1942; McNaughton & Harper 1964).

Flowering and pollination

The flowering season of P. rhoeas is longer than for other poppies that occur in Britain and Ireland. Although flowering begins rather late in the season in mid-June, and it peaks in early July, flower production still straggles on intermittently until October. The scarlet blooms attract a wide range of insect visitors, offering no nectar but easily accessible pollen in vast quantity. Honey bees are probably the most significant cross-pollinators. The flowers are outbreeders and are almost entirely self-sterile. Self-sterility is unusual in poppies and, indeed, this is true for successful annual weeds in general (Baker 1974). For further comparisons and discussion of this matter, please see the following P. dubium species account. Self-incompatibility in P. rhoeas is controlled by a complex multi-allelic gametophytic system; those wishing to know more about this topic are recommended to consult Richards (1997), Chapter 6, for a technical explanation of this rather involved genetic mechanism.

Seed dispersal

Seed ripens rapidly and is shed within four weeks of flowering, being quickly shaken out of the large pores at the top of the capsule which is borne on a long, swaying elastic stalk. This is often referred to in textbooks as the 'censer mechanism' of dispersal (McNaughton & Harper 1964). Dispersal distance was measured in a German experiment which purported to represent "near-natural conditions". However, the experimental setup could be regarded as rather artificial, since it involved dispersal over carefully maintained constantly bare ground. In any event, measurement showed that the great majority of seed travelled less than 100 cm, and the maximum distance travelled was 3.5 m (Blattner & Kadereit 1991).

Competitive ability

A range of competition experiments within and between different species populations has clearly shown that P. rhoeas reacts differently and in a complex manner to different sorts of neighbours − sometimes by mortality, sometimes by plasticity (Harper 1966). Generally, P. rhoeas is a weak aggressor when it comes to plant competition, but it is a "magnificent opportunist" (Harper 1966, p. 34). Common Poppy reacts rapidly to fill any vacancy in the environmental 'space', should some factor, eg disease, or selective browsing by an herbivore, happen to weaken neighbouring plant species. It is especially exploitive of conditions providing such openings when high nutrient levels are available (Jonsell et al. 2001). The competitive situation should be visualised, however, as a form of balance between coexisting species, rather than as one species replacing another, since mortality and competitive exclusion are not always involved. From this standpoint, plant species are often more sophisticated than we tend to allow. Biological scientists of most disciplines nearly always want to simplify and reduce the subtle patterns we find in nature. Plant (and animal) species do not belong in any fixed order of merit; "common species have their peculiar biology satisfied in frequent places; rare species may be superbly adapted to rarer sites" (Harper 1966, p. 35).

Irish occurrence

The New Atlas map shows that in Ireland, P. rhoeas is much more locally frequent to abundant and continuously distributed SE of a curve linking Newry in the north with Cavan, Longford and Athlone in the Midlands, and running south to Cork City. Elsewhere in the Republic of Ireland (RoI), P. rhoeas is now a very rare and scattered casual, while in Northern Ireland (NI) it is currently very thinly and widely distributed. The number of pre-1970 symbols on the hectad map indicates that it has declined from being a rather local plant and become a rare casual species (NI Flora Website, accessed 2002; Preston et al. 2002). It might well be argued that P. rhoeas is well down the road towards local extinction in NI, as Hackney et al. (1992) have suggested for the three counties of NE Ireland.

The pattern of occurrence in SE RoI does not appear to correlate all that well with geology, soils or climate (except perhaps a lesser number of rain days than elsewhere). However, it does reflect rather well the distribution map of 1970 tillage, and even better the distribution of wheat fields at the same date. Both of these features are mapped in the Royal Irish Academy's Atlas of Ireland (Haughton et al. 1979). Unfortunately, the same connection cannot be made in NI, where the species distribution pattern is really very fragmentary and does not appear to correlate or compare with any relevant factor, even if we include figures of rural land valuation.

Opposing the observed marked decline in the species occurrence across Ireland, however, two recent P. rhoeas Fermanagh sites arose from a sowing of 'wild flower seed'. This mode of origin is a phenomenon that in recent years has become rather common throughout the British Isles, and it is distorting the previous 'natural' distribution achieved by the species, derived from agricultural disturbance and previous crop-associated sowings. As both forms of the plant's occurrence arise entirely as a result of human activity, perhaps we should not get too agitated about this new pattern of introduction, of what is, after all, a beautiful, easily eradicated, weedy species.

British occurrence

In Britain, P. rhoeas is shown in the New Atlas to be much more common and widespread in the Midlands and SE England, extending more or less continuously up the E coast to around Dundee. Elsewhere in Britain, it is more scattered and occasional, becoming very rare and local in N Scotland. Being largely associated with arable agriculture, Common Poppy is essentially a lowland species, generally occurring below 200 m. Above this altitude, it is probably more casual than established (Grime et al. 1988; Preston et al. 2002).

European occurrence

In Europe, P. rhoeas is a common and widespread archaeophyte in W and C regions from the Mediterranean north to around 55N. However, it rapidly declines to casual status beyond this in many parts of Scandinavia. The species just reaches 60N on the Baltic coast of Sweden (Jonsell et al. 2001). P. rhoeas is largely absent from E Europe (Jalas & Suominen 1991). As elsewhere, populations rapidly declined in Europe from the 1950s onward due to use of selective herbicides, but since the 1980s it has recovered somewhat due to fallowing or set-aside (Jonsell et al. 2001).

World occurrence

Worldwide the distribution continues into SE Asia, N Africa, N & S America, Australia and New Zealand (Jonsell et al. 2001).

Uses

Corn Poppy carries with it numerous historical, folklore and medicinal traditions and uses. The seeds have a pleasant nutty flavour, are processed for Poppy seed oil, and are commonly sprinkled on cakes and bread for decoration and flavouring. Parts of the plant have also been used as a source of black dye ( Vickery 1995; Grieve 1931, p.651; Le Strange 1977, p.199-200; Mabey 1996).

Names

The origin of the genus name 'Papaver' appears to be obscure but it is a Latin name for a poppy, probably the medicinal P. somniferum, Opium or White Poppy (Gilbert-Carter 1964). It may have been derived from the Celtic 'papa', meaning 'thick milk', or Latin 'pappa' meaning 'milk', either way an obvious reference to the milky latex members of the genus contain (Melderis & Bangerter 1955; Hyam & Pankhurst 1995). The Latin specific epithet 'rhoeas' used to be the genus name. It is possibly derived from the Greek 'rhoia', meaning or referring to the 'pomegranate', Punica granatum, which both in the colour of the flower and shape of the fruit, P. rhoeas does indeed resemble (Johnson & Smith 1946; Gilbert-Carter 1964).

Grigson (1987) lists an overwhelming 50 English common names, many of which refer to the red flower colour or warn of the supposed bad luck or ill health (for example, thunder and headache, or blindness), consequent upon touching the plant. These myths were possibly used to keep children away from the poisonous plant, or out of the field to prevent trampling the corn (Vickery 1995). The gardeners' 'Shirley Poppy', which has a wide range of colour shades from scarlet to white, grey and lavender and a double form, was bred and selected from a sport of P. rhoeas (McNaughton & Harper 1964; Mabey 1996; Phillips & Rix 1999).

Threats

None.

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