Guizotia is an African genus of at least six species (probably more according to recent phylogenetic research; see Geleta & al. 2010). One species, Guizotia abyssinica, is more or less widely cultivated as an oilseed crop, especially in the (sub-) tropics. However, experimental fields are also found in Belgium. Its seed (Niger seed) also is a major component in commercial birdseed mixtures.
Two species have been recorded in the wild in Belgium. They are distinguished in the following couplet:
1. Plant glabrous or more rarely pilose, never glandular. Achenes 3-6 mm long. Receptacular paleae 5 veined, with sessile glands === Guizotia abyssinica
1. Plant always hairy, often glandular. Achenes 2-2,5 mm long. Receptacular paleae 3-veined, glandular hairy === G. scabra subsp. schimperi
Baagøe J. (1974) The genus Guizotia (Compositae). A taxonomic revision. Bot. Tidsskr. 69: 1-39.
Geleta M., Bekele E., Dagne K. & Bryngelsson T. (2010) Phylogenetics and taxonomic delimitation of the genus Guizotia (Asteraceae) based on sequences derived from various chloroplast DNA regions. Plant Syst. Evol. 289: 77-89. [available online at: https://www.researchgate.net/publication/226701560_Phylogenetics_and_tax...
Getinet A. & Sharma S.M. (1996) Niger. Guizotia abyssinica (L. f.) Cass. Promoting the conservation and use of underutilized and neglected crops. 5. Institute of Plant Genetics and Crop Plant Research, Gatersleben/International Plant Genetic Resources Institute, Rome: 59 pp. [available online at: http://www.bioversityinternational.org/uploads/tx_news/Niger__Guizotia_a...
Murthy H.N., Hiremath S.C. & Pyati A.N. (1995) Genome classification in Guizotia (Asteraceae). Cytologia 60: 67-73.
Savelsbergh E., Savelsbergh I. & Geerlings J. (1991) Spatherbst 1990 mit interessanten Adventivpflanzen im Aachener Stadtbereich Rothe Erde (TK 25 5202/232 und /241). Flor. Rundbr. 25(1): 46-53.
Tadesse M. (1999) New combinations, varieties and synonyms in African Compositae. Compositae Newsletter 33: 23-32. [available online at: http://www.biodiversitylibrary.org/item/48867#page/25/mode/1up].