Cornflower (scientific name:Centaurea cyanus50. ) is a one-year or two-year herb of the genus Centaurea in Compositae, also known as Blue Lotus, Wheelflower, Blue Centaurea[2-3]。Centaurea is about 30-70cm tall, upright, with some branches from the middle, rarely unbranched.All stems and branches are gray white, covered with thin spider silk curls.The basal leaves and lower stem leaves are long elliptic oblanceolate or lanceolate, undivided, without serration or sparse serration on the edge to pinnate split on the big head, 1-3 pairs of lateral lobes, long elliptic lanceolate, linear lanceolate or linear, without serration on the edge, large top lobes, long elliptic oblanceolate or lanceolate, with small serrations on the edge[3]。The capitulum is terminal, most or a few of which are arranged into corymbs or panicles at the top of the stems and branches. The edge of the tongue shaped flower is funnel-shaped, the edge of the petal is toothed, the central flower is tubular, and the flowers are white, red, blue, purple and other colors[3][4]。Achenes ellipsoid.Flowering and fruiting period from February to August[3]。
The origin of cornflower is southeast Europe[5], mainly distributed in the Mediterranean region and southwest Asia[6]。In China, it is mainly distributed in Xinjiang, Qinghai, Gansu, Shaanxi and Tibet[3]。The cornflower likes to have enough sunshine, but it is not resistant to humidity. It likes cool climate, but rather cold and hot[7]。The planting land should be flat without ponding or with a certain slope. The soil should be fertile, loose and well drained sandy soil.Centaurea is taproot and suitable for direct seeding. It can be sown in spring and autumn. The suitable temperature for germination is 15-20 ℃[8]。
Cornflower is currently cultivated as an ornamental plant[6], dwarf cornflower is only 20cm high, and can be used for flower beds, grass border or potted flowers[1]。High stem varieties can use courtyard background or cut flowers, and dwarf varieties, especially blue flower varieties, can be used as summer flower bed materials to enhance the cool atmosphere[9]。
Chinese name
Cornflower
Latin name
Centaurea cyanusL.[2]
Alias
Blue hibiscus、Blue flower cornflower、Wheel flower[2]
The origin of cornflower is southeast Europe, mainly distributed in the Mediterranean region and southwest Asia.It is widely cultivated in public places in Xinjiang, Qinghai, Gansu, Shaanxi, Hebei, Shandong, Jiangsu, Hubei, Hubei, Guangdong, Tibet and other places in China[3][5-6]
Named by and date
Linnaeus,Carl von,1753[10]
Synonym
Cyanus segetum(synonym)[2]
Growth environment
Prefer sunny places, not damp, prefer cool climate, rather cold, not hot.The soil should be fertile, loose and well drained sandy soil[7-8]
Identification characteristics
All stems and branches are gray white;Both sides of all stems and leaves are heterochromatic or nearly heterochromatic;Most or a few heads are arranged into corymbs or panicles at the top of stems and branches[3]
Cornflower originated in southeast Europe[5]。It has a long history and has appeared in Britain and other places since the Iron Age.Cornflower was once regarded as a harmful weed of grain crops, and its rapid reduction was caused by seed cleaning.Since the 1950s, the large-scale use of herbicides has accelerated its rapid reduction trend, and its quantity recovered in the 1980s[11]。
Origin of naming
The name of cornflower comes from the Greek Kentaureion, which means the herb of centaur Macaron.Charon is famous for his wisdom. He is familiar with various plants and can use them to treat diseases[12]。
When the ancestors of the eastern nations brought back grain seeds, they also brought back cornflowers[12]Its Chinese name originates from Japan. Because its petals shoot out like arrows in all directions and radiate like wheels, it is named "cornflower"[14]。
morphological character
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stem
Height 30-70 cm or more, erect, branched from the middle, rarely unbranched.All stems and branches are gray white, covered with thin spider silk curls[3]。
Cornflower[20]
leaf
The basal leaves and the lower stem leaves are long elliptic oblanceolate or lanceolate, not divided, the edge is not serrated or the edge is sparsely serrated to pinnately divided, 1-3 pairs of lateral lobes, and the leaves are about 15 cm long[7]。It is long elliptic lanceolate, linear lanceolate or linear, and the edge is not serrated at all. The top lobe is larger, long elliptic oblanceolate or lanceolate, and the edge is slightly serrated.The middle stem and leaf are linear, wide linear or linear lanceolate, 4-9 cm long and 4-8 mm wide. The top is acuminate, the base is wedge-shaped, without petiole. The edge of the whole edge is not serrated. The upper stem and leaf are the same shape as the middle stem and leaf, but gradually smaller.All stems and leaves have different or nearly different colors on both sides, green or grayish green on the top, sparse spider silk hair or depilation, gray white on the side, thin down[3]。
FLOWER
Most or a few of the heads are arranged into corymbs or panicles at the top of the stems and branches.The involucre is elliptic, 1-1.5 cm in diameter, with sparse spider silk hairs.The involucral bracts have about 7 layers. All involucral bracts are elliptic from outside to inside and long elliptic. The outer and middle layers, including the top appendages, are 3-6 mm long and 2-4 mm wide. The inner layer, including the top appendages, is 1-11 cm long and 3-4 mm wide.There are light brown or white appendages at the top of all bracts. The appendages in the middle and outer layers are larger, and the appendages in the inner layer are larger. All appendages are short and downward along the bracts, and the edges are fimbriate serrated.The edge flower is larger than the central flower, blue, white, red or purple, the eaves is 5-8 split, and the flower is light blue or red[3]。
The flower of cornflower[20]
fruit
The fruit is an oval achene, 3 mm long and 1.5 mm wide, with thin stripes and sparse white pubescence.The crown hairs are white or light earthy red, in two rows, the outer row is multi-layer, gradually grows towards the inner layer, up to 3 mm, the inner row is one layer, very short;All crown hairs are bristly.Flowering and fruiting period is from February to August[3]。
Distribution range
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Cornflower is native to southeast Europe[5], mainly distributed in the Mediterranean region and southwest Asia[6]In China, it is mainly cultivated in parks, gardens and campuses in Xinjiang, Qinghai, Gansu, Shaanxi, Hebei, Shandong, Jiangsu, Hubei, Guangdong and Tibet.Xinjiang and Qinghai may haveNaturalizationYisheng[3]。
Distribution Map of Cornflower in China[2]
Growth environment
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Cornflower grows in the fertile, loose and well drained sandy loam at an altitude of 200~600m[19]。
Growth habit
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Cornflower has strong adaptability, likes light, is cold resistant, is not resistant to humidity, and avoids heat.It does not have strict requirements for soil, but likes fertile, loose and well drained sandy loam[21]。Centaurea is a plant with long sunshine. In winter, the days are short and the nights are long. Artificial lighting at night can flower in advance[22]。Flowering and fruiting period is from February to August[3]。
Reproductive mode
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Cornflower is propagated by seeding method, and can be sown in spring and autumn[9]。It has strong reproductive capacity and first grew naturally in cereal crops[11]。Cornflower is usually sown in the open seedbed from September to October.The seeds are too light, so they need to be covered with soil after sowing. The thickness of the soil should be no seeds.Then water, keep the soil moist, and sprout in about 10 days.When the seedlings grow to about 10 cm high, transplant or thinned the direct seeding seedlings[23]。
cultivation techniques
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Land selection and preparation
Cornflower is suitable for growing in loose, fertile and well drained sandy soil[15]。The planting site should be a flat land with no ponding or a certain slope.Before sowing, the soil can be deeply turned, finely harrowed and leveled[8]。
If it is cultivated in a basin, the basin soil should be as good as possible to ensure its drainage and ventilation. If the soil is viscous, it can be mixed with 3-4% snakewood chips or pearl stones[15]。
Seeding
Centaurea is taproot and suitable for direct seeding. It can be sown in spring and autumn. In the north, it is mainly sown in spring. In microclimate environment, it can be sown in autumn.Spring sowing should be carried out as early as possible, usually from late April to May[8]。Cornflower likes to plant closely, but it is not suitable to plant too closely, or it will grow in vain[16]。Use a rake to gently comb the plot after sowing. After sowing, the soil should not be too thick. It is better to cover the seeds tightly. If the soil is too thick, the seedlings will not emerge evenly. After covering the soil, use a roller to roll the soil, so that the seeds and soil are closely combined.Cover non-woven fabric or straw curtain to improve ground temperature, promote seed germination, and water the cover (straw curtain) thoroughly[8]。
Water and fertilizer management
After planting, cornflower needs to do a good job in water and fertilizer management. It needs sufficient water in the germination stage and seedling stage. The soil should be kept moist for about one month. With the growth of young plants, the watering frequency should be gradually reduced[8]。At the same time, nitrogen based topdressing can be applied in the growth process to promote growth;It can be applied half a month before floweringPhosphate potash fertilizerMain fertilizers promote flowering, such asPotassium dihydrogen phosphate。Pay attention to avoid excessive fertilization, otherwise it will be beneficial to weed growth, resulting in overgrowth of flowers and reduced flowering[8]。
Weed control
Weed control is the biggest problem in the process of seedling and later maintenance. Generally, weeds are pulled out manually.Weeding time is generally about one month after sowing, and chemical herbicides such as quinoxaline can also be used for grass removal. Generally, they are applied when the cotyledons of young flower seedlings grow to 3-4 leaves[8]。
Thinning and transplanting
When the seedlings grow densely, they need to be thinned properly, which is conducive to the growth of seedlings.At the same time, the seedlings under the ground will be replanted to a relatively scarce place, so as to maintain a better overall landscape effect.Cornflower has less lateral roots and is not tolerant to transplant.If seedlings need to be transplanted, it is better to choose small seedlings. Large seedlings are not easy to survive, so they should be transplanted in cloudy days or evening with soil mounds[8]。
Disease control
powdery mildew
Cornflower is easy to catch powdery mildew in hot and humid seasons. Pay attention to avoid planting too densely, pay attention to ventilation and strengthen chemical prevention.Immediately pull out the diseased plants and burn them in a centralized way;When the disease is serious, the middle and lower parts of the plant can be sprayed with tobuzin wettable powder[16]。
Sclerotinia disease
Sclerotinia usually occurs from the base of cornflower, and can be sprayedTriadimefonWettable powder, which can also be sprayedThiophanate methylWettable powder.The seriously infected plants should be cut off in time to prevent further infection[15]。
Distinction of recent species
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name
morphological character
Distribution area
picture
Long crested cornflower（Centaurea depressaM.B.）[3]
The inner crown hairs and setae are membranous;Row crown hair bristles up to 8 mm[3]
It is distributed in Yining, Xinjiang, China and western Tibet[3]
Long crested cornflower[24]
Cornflower（Centaurea cyanusL.）[3]
The crown hairs are white or light earthy red, in two rows, the outer row is multi-layer, gradually grows towards the inner layer, up to 3 mm, the inner row is one layer, very short;All bristles[3]
The origin of cornflower is southeast Europe[5], mainly distributed in the Mediterranean region and southwest Asia[6]。It is widely cultivated in public places in Xinjiang, Qinghai, Gansu, Shaanxi, Hebei, Shandong, Jiangsu, Hubei, Hubei, Guangdong, Tibet and other places in China[3]
Cornflower[20]
Key values
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Ornamental value
The flower color of cornflower is beautiful, and the plant is tall and straight. The landscape effect of single planting or combined planting is significant.High stem varieties can use courtyard backgrounds or cut flowers, while dwarf varieties can use flower beds or potted plants, especially blue flower varieties as summer flower bed layout materials, which can improve the cooling atmosphere of cold colors, bring fresh coolness to the hot summer, and improve viewing comfort[16-17]。
ecological value
The cornflower can monitor the sulfur dioxide in the air. Once the sulfur dioxide in the air is too high, the cornflower will wither or fall down due to the loss of water and cannot bloom normally[5]。
economic value
The blue juice extracted from cornflower petals can be used not only for food dyeing, but also for processing blue ink, watercolor pigments and linen dyes.Cornflower can also be used as raw material for extracting anthocyanins.It can also be made into shampoo, bath gel, cream and other basic care products to help people look good and relax[18]。
Plant culture
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national flower
Cornflower is the national flower of Germany and Estonia.Centaurea has strong vitality and bright colors, especially blue and purple. Because of its moving story related to the first German emperor William I, it is regarded by the German people as a symbol of patriotism, optimism, tenacity, and frugality, and is recognized as the national flower of Germany[18]。
legend
At the beginning of the 19th century, the German civil war continued. Queen Louis, the mother of the first German emperor, William Friedrich Ludwig, was forced to leave Berlin with two princes during the civil war.In the process of escaping from Berlin, Louise, the Queen of Prussia, hid her children in a grove of arrow shaped chrysanthemums to avoid Napoleon's pursuit.In order to appease the children, she used cornflower to weave a wreath for the princes.Cornflower is the favorite flower of King William I, Louis' son. Since then, cornflower has also become the symbol of Prussia, and the color of Prussian military uniforms has adopted the color of cornflower.The cornflower has also become the official symbol of the annual "Demestuben Parade"[18]。
