Centaurea cyanus, commonly known as Cornflower, is an annual or biennial herbaceous plant that can grow up to 70cm tall. It is upright and branched, with a grey-white stem.
The plant has basal leaves and its flowers, which can be blue, white, red, or purple, are arranged on the top in a corymb or conical inflorescence. The flower’s involucre is elliptical and the florets are disc-shaped.
It bears elliptical, slender fruits and blooms from February to August. Cornflower mainly grows in Europe, the former Soviet Union (including the Caucasus, Central Asia, Siberia, and the Far East), and North America.
The type specimen was collected from Europe. Cultivars of this plant stand tall, with long flower stalks, making them suitable for use as cut flowers and floral arrangement materials.
Cornflower has cosmetic benefits, can help to soothe the mind, aid digestion, and promote smooth urination. Cornflower hydrosol is a gentle, natural skin cleanser, and the floral water can be used to nourish hair and moisturize skin.
It can aid digestion and alleviate rheumatic pain. Dwarf varieties, which only grow to about 20 cm high, can be used for flower beds, turf edging, or as potted ornamental plants.
The Cornflower is an annual or biennial herbaceous plant that grows 30-70 cm tall or higher. It stands upright, branching from the middle, and rarely has no branches.
All of its stems and branches are grey-white and covered with thin, spider silk-like curly hairs. Its basal and lower stem leaves are long and elliptical or lanceolate, with margins that are either smooth or have sparse, serrated teeth.
Its middle stem leaves are linear or lanceolate, measuring 4-9 cm in length and 4-8 mm in width. The upper stem leaves are similar in shape to the middle stem leaves, but gradually smaller.
All the stem leaves are of a different color on the two sides, with the upper side green or grey-green and the lower side grey-white, covered with thin, fluffy hairs.
The inflorescence is arranged in a corymb or conical inflorescence at the top of the stem. The involucre is elliptical and 1-1.5 cm in diameter, covered with sparse, spider silk-like hairs.
The florets are disc-shaped and can be blue, white, red, or purple. The fruits are slender and elliptical, 3mm long and 1.5mm wide, with fine stripes and sparse white soft hairs.
The pappus is white or light terra-cotta colored, arranged in two rows, with the outer row being multilayered and gradually longer towards the inner layer. The inner row is extremely short. The plant fruits from February to August.
Cornflower is highly adaptable and thrives in sunny conditions. It is intolerant of damp and shady conditions and should be planted in sunny, well-drained areas to prevent death caused by dampness.
It can withstand cold temperatures and prefers cool climates, but does not tolerate heat. It prefers fertile, loose, and well-drained sandy soil.
Cornflower is mainly found in Europe, the former Soviet Union (including the Caucasus, Central Asia, Siberia, and the Far East), and North America. The type specimen was collected from Europe.
The pathogen of this disease is sclerotinia. This disease mainly damages the base of the stem. In warmer conditions, the stem often shows watery, light brown spots.
In severe cases, the affected area turns gray-white and the tissue later rots. The upper part of the plant, including the stem and leaves, wilts. This disease is most likely to occur in humid conditions around 15℃ during spring and fall.
To prevent and control this disease, avoid overcrowding when planting; if a diseased plant is found, immediately pull it out and burn it. When the disease is severe, a 70% solution of Thiram wettable powder diluted 1000 times can be sprayed on the lower part of the plant.
Symptoms: The infected leaves show irregular light gray-green to light red spots, and a layer of downy mildew covers the spots on the back of the leaves, causing the leaves to die.
Pathogen: The causative agent is Bremia lactucae Regel, a member of the Oomycetes class, Peronosporales order, and Peronospora genus.
Disease Pattern: The pathogen overwinters in the diseased tissues as oospores. The following year, the oospores germinate and produce a germ tube to infect and damage the host. Young plants are prone to infection. High humidity facilitates the occurrence of the disease.
Prevention:
① Remove diseased plants as soon as they are discovered and dispose of them properly.
② Do not overcrowd when planting, maintain good ventilation and sunlight conditions.
③ Medicinal prevention: When the disease occurs, spray 1:1:100 Bordeaux mixture, or 65% Mancozeb wettable powder diluted 500-800 times, or 25% Metalaxyl diluted 800-1000 times, or 40% Aluminum phosphide diluted 200-300 times.
The tall varieties stand upright with long flower stems, suitable for cut flowers and floral arrangements. The dwarf varieties are only 20 cm tall and can be used for flower beds, lawn edging, or potted plants. Large patches of natural growth are striking.
Tall varieties can be arranged with other flowers in flower beds and gardens. They can also be planted along roadsides or in lawns, their graceful shape and beautiful flowers look very natural. They can also be used as cut flowers.
It can nourish the skin, relax your mind, aid digestion, and facilitate urination. Cornflower hydrosol is a gentle natural skin cleanser, and the floral water can be used for hair care and skin moisturizing.
It can aid digestion and alleviate rheumatic pain. It helps treat stomach pain, prevent gastritis, gastrointestinal discomfort, bronchitis. It is a heat-intolerant and cold-tolerant flower, so it is difficult to grow well in Taiwan in the summer, unless it is planted in a high and cold area.
It can be brewed alone or paired with green tea. Take four teaspoons of cornflower and brew with boiling water. The pale purple tea can be enhanced with a little honey for flavor.
The floral language of the cornflower is meeting and happiness.
The cornflower represents meticulousness, elegance, and also happiness.
Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.
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