The largest collection of CGN with 4911 accessions, divided in 4466 accessions of cultivated Triticum species, 445 accessions of 16 wild species and 22 accessions of synthetic hybrids. Besides the former working collection of the SVP, a substantial amount of the collection originated from the former 'Wageningen Triticinae Collection'(WTC) established between 1965 and 1985 by Dr. A. Zeven from the IVP (van Loosdrecht, 1986). Also some material from the CPRO-DLO and IPO-DLO has been included in the collection.
The classification of the wheat collection is according to the system of Morris and Sears (1986).
The following 16 wild species are included in the wheat collection: T. monococcum, T. turgidum var. dicoccoides (wild emmer), T. triunciale, T. kotschyi, T. columnare, T. lorentii, T. triaristatum, T. ovatum, T. cylindricum, T. caudatum, T. bicorne, T. longissimum, T. speltoides, T. squarrosum, T. crassum and T. ventricosum. With exception of some tetraploids, the majority of these species is diploid. A large part (257) of the accessions are wild emmer, mainly collected in Israel.
The cultivated group compromises material of T. monococcum, the T. turgidum group, T. timopheevi var.timopheevi and the T. aestivum group. The latter group includes the hexaploid 'spelt', 'compactum', 'sphaeroccocum' and 'aestivum' wheats, whereas the 'durum', 'dicoccon', 'carthlicum', 'turgidum' and 'polonicum' wheats belong to the tetraploid T. turgidum group.
Most cultivated wheats of the collection belong to the T. aestivum group, particularly to the T. aestivum group aestivum. This group includes 2007 accessions of spring wheat, 104 intermediate types and 1890 winter wheats. Approximately 50% of this material is of European and North American origin, particularly the cultivars, but also a substantial number of research material and landraces. The European landraces are predominantly from East, South and Central Europe. Only 3 old Dutch winter wheat landraces are present in the collection namely, 'Zeeuwse', 'Diekhuis tarwe' and 'Gelderse Ris'. The T. aestivum group aestivum also includes 1400 accessions from Asia and 373 from Africa. Of these accessions, 90% are landraces collected between 1953 and 1981 in the centres of diversity (Middle East, Nepal, Pakistan, India, N.Africa and Ethiopia). Only a limited number of accessions are from South America (95) and Australia and New Zealand(78).
The tetraploid T. turgidum group consists for nearly 60% of 'durum' wheats, mainly landraces from Mediterranean countries. In this group also 62 cultivated spring and winter Emmer wheats are included.