Black petioles of flowers and stems, contrasting with the blue or pink flowers, and giving an interest in the plant in winter.
The color depends on the pH and the content of the ground/substrate in alumina during the formation of the flower bud (previous year) and during flowering. An acidic pH (<7) and a high alumina content (alumina sulfate, Shale) causes a blue flower, otherwise the flowers will be pink to pale purple.
Sport of 'Blaumeise' obtained in 2001 by André Van Zoest in the Netherlands. Medium sized variety with flat head inflorescences (lacecap) compound with large blue sterile flowers (purple basic pH) surrounding fertile apetalous blue-purple flowers. Stems and stalks of flowers are black, especially in spring and summer, giving a special interest to the plant and in contrast with the flowers.