Centaurea macrocephala - seeds

Centaurea macrocephala, or Giant Knapweed, is a robust perennial plant that is found in the Caucasus, Siberia, and the Mediterranean basin, mainly on limestone soils. It quickly forms a large clump of sturdy upright stems and is adorned in summer with large golden yellow, fluffy flower heads, loved by bees, golden chafer beetles, and butterflies. It is stunning at the back of naturalistic-style borders and a good flower for cutting.

Centaurea macrocephala (synonym Grossheimia macrocephala) is a perennial herbaceous plant of the aster family, just like cornflower and thistles. This large and beautiful wild species is native to subalpine fields in Armenia and neighbouring regions of Turkey. Depending on the soil fertility, this centaurea can reach up to 1.20 m high, with a width of 80 cm. Its growth is rapid, and the plant is capable of flowering in the second year. It has a taproot that first forms a basal rosette of large leaves. Then, it develops strong, thick, hairy stems. These stems bear numerous sessile (without petiole), oblong and wavy leaves with fine hairs, entire or coarsely lobed and bright green. The leaves at the top of the stems have a fine terminal spine. Flowering takes place in July-August and lasts about a month. At the end of the stems, solitary flower heads measuring 9 cm in diameter appear. Each head is composed of numerous finely tubular ligulate, very bright yellow flowers. The large flower buds are covered with brown scales, often split in the middle, and have fairly long whitish cilia. This flowering is very nectar-rich. After pollination, fruits are formed. These are achenes that will be dispersed by the wind, allowing the plant to self-seed in the surrounding area. The deciduous foliage is absent in winter.

Centaurea macrocephala, with its resemblance to a giant dandelion, is best at the back of sunny borders. Undemanding and frugal in water, it will accompany large blue thistles like Onopordum nervosum, Cynara cardunculus, Eryngium giganteum in mediocre, even rocky and fairly dry soils. It can be associated with other tall, slightly wild plants like Verbascum olympicum, Ferula communis... for a picturesque effect, or in a large rockery. Its flowers hold up well in a vase and can be used in dried or fresh compositions.