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Centaurea cyanus

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The Cornflower (Centaurea cyanus) is a small annual flowering plant in the family Asteraceae, native to Europe. It is an annual plant growing to 40-90 cm tall, with gray-green branched stems. The leaves are lanceolate, 1-4 cm long. The flowers are most commonly an intense blue colour, produced in flower-heads (capitula) 1.5-3 cm diameter, with a ring of a few large, spreading ray florets surrounding a central cluster of disc florets.

Cornflower prefers arable fields, often on sandy, acidic soils. Flowers are self-incompatible and are borne between May and August. The seeds, which are believed to remain viable for several years, generally germinate during the following spring with a second flush in late summer. This species was often found in association with corn marigold (Chrysanthemum segetum), which also germinates in spring.

The same anthocyanin pigment makes roses red but cornflowers blue, a phenomenon that has thus far not been entirely explained. The anthocyanin in the blue cornflower (Centaurea cyanus) has been known for many years to be cyanidin 3,5-diglucoside, namely cyanin. However, during my work with cornflower in the Potions lab, it became evident that the major anthocyanin in the blue cornflower is not cyanin but cyanidin 3-succinyl glucoside 5-glucoside. This anthocyanin has not been reported in the literature and is tentatively called “centaurocyanin”. Centaurocyanin is chromatographically identical with the anthocyanin contained in crystalline protocyanin, the blue pigment from the cornflower. thus, there seems no doubt that this anthocyanin, but not cyanin, forms the blue complex pigment protocyanin. The bright blue colour comes from the arrangement of four metal ions, which bind to a complex of six different molecules, made up from two pigments. This pigment structure is completely different to the pigment found in other blue flowers. A strategically placed iron ion and magnesium ion give the blue colour, while two calcium ions give the structure stability. This tetrametal complex may represent a previously undiscovered type of supermolecular pigment.

In folklore, cornflowers were worn by young men in love; if the flower faded too quickly, it was taken as a sign that the man’s love was unrequited. This practice has earned them the colloquial name of Bachelor’s Buttons, as they are generally referred to within the floral industry.

In herbalism a decoction of cornflower is effective in treating conjunctivitis, and as a wash for tired eyes. This is no small consolation, given the brutally excessive hours that Hogwarts students are expected to spend on homework and other extracurricular studies.

In the past C. cyanus often grew as a weed in crop fields. It is now endangered in its native habitat by agricultural intensification, particularly over-use of herbicides, destroying its habitat; in the United Kingdom it has declined from 264 sites to just 4 sites in the last 20 years. Cornflower once occurred throughout the UK and was a troublesome weed of arable land. Between 1930 and 1960 it was recorded from 264 ten km squares, but by 1979 it had declined to fewer than 60 ten km squares. Today, self-sustaining populations are thought to be confined to only one site in Suffolk, one on the Isle of Wight, one in Lincolnshire and one in St. Mary Mead. Isolated plants still occur over a large area of the south and east of England and in Wales, although many are due to introductions from wildflower seed mixtures and most persist for no longer than a year. Large numbers sometimes occur when there are deep excavations for roads and pipelines. In Europe as a whole, cornflower is not threatened and is still widely distributed, although it has declined in much of north-west Europe.

In the UK the cornflower is now classified as Endangered. It receives general protection under the Wildlife and Countryside Act.

Agricultural changes have been largely responsible for the decline of cornflower, including the increased use of herbicides and fertilisers, the development of highly competitive crop varieties, the destruction of field-edge refuges, the demise of traditional crop rotations, and the conversion of marginal arable land to pasture. The same factors are now providing constraints on its recovery.

A plan of action aimed at the restoration of cornflower habitat must develop and maintain viable populations at all extant native sites where the species is long-established and encourage the natural colonisation of new sites.

The development of relevant agri-environment schemes, such as the pilot Arable Stewardship Scheme in England, should be encouraged as a potential means of re-establishing cornflower in the countryside. When reviewing such schemes, consideration must be given to whether changes are needed to increase their potential benefits for this and other threatened arable species.

A network of suitable habitats within the vicinity of cornflower sites needs to be developed, thereby providing opportunities for its spread. Seed should be collected from all extant native sites and any restored sites and deposited in a seed bank established for this purpose. As far as possible, it must be ensured that any seed of cornflower included in wildflower seed mixtures is of native origin.

As far as possible, it should be ensured that all relevant agri environment project officers are advised of locations of this species, its importance, management requirements and potential threats. On sites where cornflower is a significant consideration, landowners and managers should be advised of the presence and importance of this species, specific management for its conservation, and any potentially damaging actions. Particular attention should be given to optimal cultivation and harvest times.

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Where Have All the Flowers Gone?
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