Plant of the Week – June 29th 2026 – Cornflower (Centaurea cyanthus) – Botany in Scotland

This plant was once common as a persistent weed of cereal crops but was driven to near extinction in Britain by the intensification of agriculture, luckily surviving as a colourful garden flower. However, in recent decades it has appeared in urban landscapes, having been sown with seeds of other species to create ‘wildflower meadows’. In this situation, it is praised for its vibrant blue flowers and has become famous for its abundant nectar. How fortunes do change!

Typical ‘wildflower meadow’, late June 2026, on the edge of a playing field, Ballantrae in South Ayrshire. The meadow is dominated by the yellow Glebionis segetum (Corn Marigold) with several other species interspersed, including the blue Cornflower. Both Cornflower and Corn Marigold are annual plants, thought to have been introduced in ancient times, and both were troublesome weeds of farmland until the 1950s. Image: John Grace.

Cicely Mary Barker told part of its story, from weed to herbaceous border, in a poem called the Song of the Cornflower Fairy in her book Flower Fairies of the Garden (published 1944). The speaker is her cornflower fairy, exquisitely depicted in shades of blue.

The decline of many of our agricultural weeds is usually attributed to the introduction of herbicides although this did not occur until the 1950s and Barker published her poem in 1944. Other factors must have contributed to the decline: improved cleaning of cereal seeds to remove weed seeds, the use of fertilisers to encourage vigour of the cereal plants and to enable closer planting of the crop, the loss of field margins where wild flowers often flourished; probably they all played a part.

It may be useful to reflect: what was the original habitat of the cornflower, before it was an agricultural weed or a component of ‘wildflower meadows’?. Godwin and Vishnu-Mittre (1975) found traces of its pollen in early Neolithic deposits, appearing at about the same time as pollen of cereals. Godwin speculated that its original habitat in Britain was on scree slopes and alluvial deposits in late glacial tundra.

By 1994 cornflower was described as a rare plant needing protection (Stewart et al. 1994) and it was still rare by the time of the 3^rd edition of the British red data book on vascular plants (Wigginton 1999). However, in the most recent red data book (Stroh et al. 2025) it is noted as a species of ‘least concern’. It is back from the brink.

Side view of inflorescence. Note the 4 rows of bracts. Image: John Grace.

Cornflower¹ belongs to the daisy family, Asteraceae. The species is native to southern parts of Europe and perhaps western Asia and has become naturalised in several other regions. It was once thought to be a native in Britain but now is considered to have arrived on our shores in ancient times (an ‘archaeophyte’) perhaps occurring as a contaminant in imported sacks of cereal seeds². It was a well-known weed of arable crops in Anglo-Saxon times, later earning the common name of hurt-sickle, as farmers believed that it would blunt their sickles when cutting cereal fields. During the nineteenth century, cornflower was so common that it became an iconic feature of the British countryside and an emblem for Harrow school. Alongside species such as poppy (Papaver rhoeas) and corn marigold (Glebionis segetum), it contributed to the colourful displays associated with traditional cornfields. On the Continent it occupied similar habitats: Vincent Van Gogh painted his Wheatfield With Cornflowers during the final weeks of his life in 1890.

In bud. Note the stem, roughly hairy (‘hispid’) and also quite tough. Image: John Grace.

In France it has also been a troublesome weed – especially in fields of sunflowers. By the early 2000s, the species was almost extinct in conventional agricultural fields, persisting only on marginal land and organic farms (D’Agostino and Abeli, 2025). These authors have provided an extensive review of the biology and ecology of cornflower, from which I have gleaned the following information about the plant and its life cycle.

The inflorescence contains 25–35 florets. The sterile florets are ray-like, 20–25 mm, and serve to attract insects. The fertile flowers are 10–15 mm in size. The anthers are 4 mm – 6.2 mm long, purple: the styles are white with purple stigmatic branches (information from D’Agostino and Abeli, 2025). Image: John Grace.

(i) Cornflower is an annual plant but has a tap root. It grows to between 30 and 90 centimetres in height with slender and branching stems, covered with fine hairs. The leaves are narrow, lance-shaped, and similarly covered with soft hairs, giving the plant a slightly silvery appearance. The flower heads, which appear from June to September, are composed of numerous individual florets. The wild form is bright blue, but cultivated varieties may produce pink, white, purple, or red flowers.

(ii) Flowers are pollinated by large flying insects, most notably by bumble bees.

(iii) Cross-pollination is usually necessary, although ‘selfing’ may now sometimes occur due to the reduction in the number of wild pollinating insects (the authors say that “inbreeding depression has resulted in reduced fitness of individuals, leading the species, in some cases, to have pseudo-self-compatible individuals”).

(iv) Seeds are produced in the upper layers of the crop canopy and are dispersed both before and during harvesting of the crops, through the action of the combine harvester (previously the sickle) thus replenishing the soil seed ‘bank’.

(v) Ants disperse and ‘sow’ the seeds, attracted by the nutrient-rich appendages (‘elaiosomes’) attached to the seeds. 

(vi) Seeds are rather large (3-3.5 mm long) and can remain viable in soil for three or four years.

(vii) Germination occurs in autumn (the plants can overwinter as rosettes) or in the spring.

(viii) There are signs that this species may be developing resistance to some of the herbicides used in Poland (Stankiewicz-Kosyl et al. 2021).

Example of a public awareness sign for a wildflower meadow (Ballantrae, Ayrshire). Image: John Grace

Public awareness campaigns promoting wildflower conservation have further increased appreciation of cornflowers. Their vibrant flowers make them highly visible ambassadors for wider biodiversity initiatives. As a result, the species enjoys a level of public recognition. Despite these positive developments, conservationists continue to stress that artificial meadows and garden populations should not obscure the loss of naturally occurring arable communities. We do not know how well the annual plants of wildflower meadows will survive, year on year (Cornwell et al 2025). Will they need re-sowing? Maintaining cornflower as part of functioning farmland ecosystems remains an important objective, and I shall be looking out for these flowers in Scottish farmland during this summer.

Distribution of Centaurea cyanus in Britain and Ireland, from BSBI/Maps.

The current distribution shows the species to be present throughout lowland Britain and part of Ireland. My doubts about the map relate to the behaviour of the BSBI recorders. The usual BSBI practice is to record observations from the ‘wild’ and to avoid gardens. Municipal flower beds are not normally recorded and perhaps ‘wildflower meadows’ are thus ignored by some recorders.

Global distribution according to Kew’s Plants of the World Online (green shows the native distribution, purple shows ‘introduced’). It also occurs in SE Australia and New Zealand.

The global distribution shows a wide tolerance of cold for a plant that originally came from the warmer parts of Europe. There may be climatically-adapted ecotypes, but I have been unable to find any research on this aspect.

Notes

1. Other common names for Centaurea cyanus are Bachelor’s Button, Garden Cornflower, Bluebottle, Raggedy Sailors.
2. Godwin’s evidence suggests it may indeed be truly native. It may have been present in the Neolithic but suffered extinction before being re-introduced in a later period as an accidental contaminant of imported cereal seed.

References consulted

Brenchley WE (1920) Weeds of Farmland. Longman’s London (my edition is the Cornell Digital Library Digital Collection).

Cornwell I et al (2025). Sown and self-seeding species in planted wildflower meadows increase floral abundance and richness in a Scottish semi-natural coastal grassland. Plant Ecology & Diversity, 18(5-6), 249-266.

D’Agostino M and Abeli T (2025) Biological flora of Central Europe: Centaurea cyanus L.,Perspectives in Plant Ecology, Evolution and Systematics, 68, 125874.

Godwin H and Vishnu-Mittre (1975) Studies of the Post-Glacial History of British Vegetation: XVI. Flandrian Deposits of the Fenland Margin at Holme Fen and Whittlesey Mere, Hunts. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences,

Salisbury E (1964) Weeds and Aliens (2^nd Edition). Collins.

Stankiewicz-Kosyl M et al. (2021) Herbicide Resistance of Centaurea cyanus L. in Poland in the Context of Its Management. Agronomy. 2021; 11(10):1954.

Stewart A, Pearman DA and Preston CD (1994) Scarce plants in Britain. BSBI.

Stroh, P.A.,  et al. (2025) A new vascular plant Red List for Great Britain. British & Irish Botany, 7(3), 148-216.

Wiggington MJ (1999) British red data books: Vascular plants. 3rd ed. Peterborough: Joint Nature Conservation Committee.

©John Grace