Centaurea cyanus L.

Centaurea concinna (Boiss. & A. Huet.) Trautv., Centaurea concinna Willd. ex Steud.,

Centaurea cyaneum St.-Lag., Centaurea cyanus var. denudata Suksd., Centaurea hoffmanniana Asch., Centaurea lanata Roxb., Centaurea pulcherrima Wight ex DC., Centaurea pulchra DC., Centaurea rhizocephala Trautv., Centaurea segetalis Salisb., Centaurea umbrosa Reut., Cyanus arvensis Moench, Cyanus cyanus Hill, Cyanus dentato-folius Gilib., Cyanus vulgaris Delarbre, Jacea segetum (Hill) Lam., Leucacantha cyanus (L.) Nieuwl. & Lunell.

Asteraceae

Bachelors Button, Blue Bottle, Blue Cap, Blue poppy, Blueblow, Bluebonnets, Bluebottle, Boutonniere Flower, Cornflower, Cyani Flower, Garden Cornflower, Hurtsickle

Cornflower is indigenous to Europe, where it occurs as a weed in fields.

It is found especially on porous, nutrient-rich soils with pH 6.6–7.6 in grain fields, rye fields, fallow land, wasteland and roadsides in its native range. It thrives in full sun but has high average daily water requirement.

The flowers are eaten cooked or raw as vegetables in salads or as garnish (Facciola 1990; Bown 1995; Rop et al. 2012). An edible blue dye is obtained from the flowers, used for coloring sugar and confections. The young shoots are also eaten (Chiej 1984).

A robust, herbaceous annual, 20–85 cm with grey-green, distally branched, weakly tomentose, slender stem. Leaves gray-tomentose, alternate, basal leaves linear-lanceolate, 3–10 cm, with entire margins sparsely toothed and acute apices, petiolated, cauline leaves linear, sessile with entire margins. Flower heads (capitula) rounded or flat-topped cymbiform arrays, 2.5–3.5 cm diameter, on long peduncles surrounded by campanulate involucral bracts. Phyllaries green, ovate to oblong, tomentose to subglabrous, margins and erect appendages white to dark brown or black fringed with slender teeth (Plate 1). Capitula’s ray florets 25–35, violet blue–blue (Plate 1) (sometimes pinkish or white), obliquely funnel-shaped, tip lobed, those of sterile florets raylike and enlarged, 20–25 mm those of fertile florets 10–15 mm; disc florets violet blue, tubular, in the centre of capitula. Stamens 5. Pistil of 2 fused carpels. Fruit elliptic, flattish, yellowish, fine-haired, 3.5–4 mm (0.14–0.16 in.) long cypsela, tip with short, stiff unequal bristles.

Rop et al. (2012) reported that edible flowers of Centaurea cyanus had a dry matter content (%w/w) of 9.75 %, crude protein of 6.73 g/kg and the following elements (mg/kg fresh mass (FM): P 534.48 mg, K 3568.77 mg, Ca 246.18 mg, Mg 138.49 mg, Na 74.28 mg, Fe 6.89 mg, Mn 2.29 mg, Cu 0.89 mg, Zn 7.59 mg and Mo 0.49 mg.

From the aerial plant parts, six flavonoid aglycons (quercetin, kaempferol, isorhamnetin, apigenin, luteolin, hispidulin), 8 flavonoid glucosides (quercetin 7-O-β-d-glucoside (quercimeritrin), isorhamnetin-7-O-β-d-glucoside, kaempferol 7-O-β-d-glucoside, apigenin 4′-O-β-d-glucoside, apigenin 7-O-β-d-glucoside (cosmossiin), luteolin 7-O-β-d-glucoside (cynaroside), apigenin 7-apioglucoside (apiin), luteolin 7-apioglucoside (graveobioside)) and four hydroxycinnamic acids (caffeic, chlorogenic, neochlorogenic and isochlorogenic acids) were isolated (Litvinenko and Bubenchikova 1988). Also, amino acids arginine, serine, methionine, proline, glutamic acid, tryptophan, alanine, phenylalanine and threonine were detected. Apigenin-4′-O-(6-O-malonil-glucoside)-7-O-glucuronide, methyl-apigenin and methyl-vitexin, cyanidin-3-O-succinyl-glucoside-5-O-glucoside/centaurocyanin (the marker compound), cyanidin-3,5-diglucoside/cyanidin, quercetin-3-O-gluco-rhamnoside/rutoside, isorhamnetin-7-O-glucoside, naringenin and naringenin-7-O-gluco-rhamnoside were also reported from cornflower (Pirvu et al. 2012).