CYTOGENETIC STUDIES IN THE GENUS ORNITHOGALUM L.
The transfer of desirable floristic traits between Ornithogalum species indigenous to Southern Africa is often hampered by the failure of intra- and interspecific crosses. The failure can be due to lack of seed set, zygote or seed inviability or karyotypic and genic differences resulting in unstable meiotic pairing in hybrids. Reduction in F1 hybrid pollen fertility and failure of meiosis in the microspore mother cells resulted in polyploid pollen in some interspecific crosses. Based on studies of the above factors some of the species in the miniatum-maculatum group of Leighton (1944a,b; 1945) could be grouped together as the specie, O. dubium. A second group could form the species O. thyrsoides. Seven species are cytogenetically isolated, namely, O. pruinosum, O. lacteum, O. species nov., O. synanthifolium, O. conicum, O. ranunculoides and O. maculatum. The most recent revision of Ornithogalum incorporates some of the above results, but not others.
Littlejohn, G.M., Biomerus, L.M., Pienaar, R. de V. and van Niekerk, H.A. (1992). CYTOGENETIC STUDIES IN THE GENUS ORNITHOGALUM L.. Acta Hortic. 325, 879-882