Family: Dipsacaceae
Genus: Knautia
Species: arvensis
(i) General background on the plant
A wild herb native to many parts of Europe where it is most common in dry grassy fields, dry pastures, banks and generally open, sunny situations. It is not found further than 68°N in Europe.
Field scabious is a perennial which develops a deeply penetrating taproot, with lateral roots at some depth. The plant is erect and may reach heights of 25 - 100cm and profuse tillering can form clumps up to 50cm diameter when well established. The plant is very variable, particularly in the form of the leaves. Earliest formed rosette leaves are pointed and oval with a prominent midrib, later leaves are notched, the notching becoming more pronounced in successive leaves. Stem leaves may be reduced to strap-like structures with a little tissue around the midrib. Stems are thin, tough and lightly ridged. Flowers are hemispherical, pale lilac or light blue, occasionally pink or white. Earliest flowers are formed at the outer ends of the main stems and are succeeded by later flowers on branch and secondary stems. Marginal flowers are larger than the central. Flowers are protandrous and visited by bees and butterflies.
The seeds are exposed and change colour from light green / yellow to tan. Seeds fall to the ground when ripe.
(ii) Details of quality characters
Field scabious is now regarded as a potential oilseed crop. The seeds contain approximately 25% oil, of which 33 - 40% is saturated caprylic (C8:0) and capric acids (C10:0). At present these are only directly available from coconut and palm kernel oil, which are principally imported as sources of lauric acid for use in soap and detergent manufacture.
(iii) Current production and yields
A European-based source of these acids would be highly prized by the oleochemical industry and preliminary studies have been undertaken. Recorded yields of field scabious grown as a crop have been poor to date - up to 0.35t seed per ha for annual crops and 0.7t/ha for perennial ones. However there is still much work to be done to optimise the agronomy of this plant.
(iv) Constraints upon production
There is little information available yet regarding basic agronomy of the crop. The plant naturally exhibits great variability, particularly in earliness and length of flowering period. Breeding programmes will be necessary to improve some of these characters. The long flowering period and exposed seed heads makes timing of harvest very difficult. It is also by nature a perennial, although it will flower and produce seed if grown as an annual.
(v) Markets and market potential
Caprylic and capric acids are increasingly being used in high performance oils for jet engines and other lubricants of high quality, also in the preparation of some valued dietary fats. Caprylic acid is specifically used in organic synthesis of of drugs, fragrances, fungicides and in ore separation, also in coating additives. Capric acid is specifically used in synthesis of fragrance raw materials, plasticizers and resins, also in skin preparations.
(v) Other information
Optimum plant population is yet to be established for field scabious. Best yields have been obtained when grown as a perennial, hence the best method of culture may be to sow a spring crop which is intended to stay in the ground for a few years. Establishment and early growth are slow, so weed control is very important until well-established. Linuron products applied pre-emergence have been effective without evidence of any toxic effects. Fertiliser requirements have not been established, but are not expected to be high.
(vi) Contacts
(vii) References
Clapham, A.R., Tutin, T.G. and Warburg, E.F. (1962). Flora of the British Isles. Cambridge University Press
Smith, N.O., Maclean, I. and Miller, F.A. and Carruthers, S.P. (1997). Crops for Energy and Industry in Europe. Office for Official Publications of the European Communities.
Zoebelein, Hans. (1997). Dictionary of Renewable Resources. VCH.