Centaurea cyanus

Scientific Name Centaurea cyanus
Common Names English: Cornflower; German: Kornblume; French: Bleuet des champs; Spanish: Aciano, Azulejo
Description Annual in summer crops, hibernating to biennial in winter crops, 20-70 cm (7.87 - 27.55 inch) tall.

Descriptions

Characteristic Features

Young plant with rosettes, shiny blue flowers.

Cotyledons

Dense, vigorous, broad-oval to oval, narrowing to the base.

Stems

Up to 1 m (39.37 inch) tall, tomentose to arachnoid pubescent, herbaceous, loosely wooly-hairy when young but losing this as they mature.

Leaves

Leaves narrow, often linear, mostly entire, or the lower ones sometimes shallowly toothed or lobed, up to 13 cm (5.12 inch) long and 1 cm (0.39 inch) wide, excluding the lobes, white-woolly on the lower surface.

Propagatio Organs

Flowers

Flower heads bowl-shaped, solitary at the ends of the branches, 1-2 cm (0.39 - 0.78 inch) tall.
Phyllaries ovoid to lanceolate, with fine vertical lines, the edges papery and fringed, lacking spines.
The flowers are an intense blue color, produced in flowerheads (capitula), 1.5 - 3 cm (0.59 - 1.18 inch) diameter, with a ring of a few large, spreading ray florets surrounding a central cluster of disc florets.

Flowering Period

Summer - autumn.

Fruit

2 - 4 mm (0.078 - 0.157 inch) long. Achene 3 - 4 mm (0.12 - 0.16 inch), yellowish-brown to blackish, 3.5 - 4 mm (0.14 - 0.16 inch) long, tipped by orange-brown pappus of bristles.

Seeds

Silky-cottony seeds, whitely at the end, otherwise blue-gray with white stripes. Germination in autumn and spring.

Viability Of Seeds

5 - 10 years.

Propagation

Germination depth up to 3 cm (1.18 inch).
700 - 1,600 seeds/plant.

Occurrence

Habitat

Meadows, pastures, waysides, parks.

Soil

Loose, nutrient-rich loam and sandy soils.

Additional Crop Information

Cereals, especially winter cereals and oil seed rape, sparsley in potatoes or sugar beets.

Agricultural Importance

C. cyanus causes high yield reduction due to a strong competition for light but usually does not interfere with combine harvesting.

Control

Integrated Crop Management

Careful seed cleaning and monitoring of seed propagators.

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