Abstract
A diploid apomict, in addition to the already known triploid apomict is described from the W. Himalayas in the widely ranging species Adiantum lunulatum Burm. On the basis of morphological evidence it is suggested that the whole complex be split up into two, viz., A. lunulatum (s.s.) comprising the universally known triploid apomict, the diploid and tetraploid sexual from S. India and the diploid apomict from W. Himalayas and S. India. The other species, A. teestae Verma would comprise of the E. Himalayan diploid sexual and diploid apomict forms together with the tetraploid sexual. Chromosomal associations in the 16-spore mother-celled sporangia have been analysed and on this eviednce the origin of the two polyploid types in Adiantum lunulatum is discussed. It is argued that the diploid apomict A. lunulatum (sensu stricto) probably originated in a previously sexual taxon. Genetically speaking, the diploid apomict is AA', while the triploid is AA'B in constitution but still possessing approximately X pairs+X univalents.
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