Biological Flora of Britain and Ireland: Knautia arvensis

Abstract

This account presents information on all aspects of the biology of Knautia arvensis (L.) Coult. (Field Scabious) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Knautia arvensis is a perennial hemicryptophyte, with a tap root system, and bluish-lilac inflorescences. It is native in Britain. It occurs predominantly on well-drained to moderately dry soils such as dry grassy fields, pastures, roadsides and dry hedge banks. It has a vast Eurasian native distribution. Reproduction occurs through the production of seeds and rhizomes, though K. arvensis possesses very limited clonal growth. It has a gynodioecious breeding system. Flowers are nectariferous and insect pollinated, showing sexual dimorphism in several traits. The hermaphroditic flowers are protandrous and self-compatible. Flowers are mainly pollinated by butterflies (Lepidoptera), Hymenoptera, Coleoptera and Diptera. Knautia is a genus noteworthy for its high occurrence of hybridisation and polyploidy. Knautia arvensis has the widest distribution within the genus, and hybridisation both within members of the same group and with taxa of other groups is frequently reported. Although declining in natural habitats within England, K. arvensis is increasingly being sown within wildflower seed mixtures used in restoration schemes across the country, as it is a late flowering species that provides a good source of nectar for pollinators.