Loranthaceae, chiefly a tropical family, extend into the temperate zones of both hemi spheres. They include parasitic herbs, shrubs and rarely trees. There have been many nomencla tural changes and the taxonomy of the family is somewhat confusing. De Candolle (1830) divided the family into two groups, on the basis of the presence or absence of calyculus, which were treated by most systematists as subfamilies, Loranthoideae with calyculus and Viscoideae lacking calyculus. In more recent classifications, they have been raised to the status of separate families, Loranthaceae and Viscaceae respectively (Barlow 1964, Dahlgren 1977). There is also disagreement with regard to the delimitation of tribes and genera. The classification of Danser (1929, 1933) is now widely followed. The family has been of interest as some species cause considerable damages to timber trees and fruit crops. Despite the large number and wide distribution of species, very little is known on the cyto logy of the Loranthaceae. Chromosome numbers are known in about 73 species of 24 genera mostly from meiotic studies. The most important contributions to the cytology of the family are those of Barlow (1963, 1964) who made extensive cytotaxonomical studies of Australian species. Chromosome numbers of a few species have been determined by Bhaumic (1971), Bir et al. (1980, 1982), Wiens (1964) and others. In the present study detailed investigations of meiosis in 14 taxa (13 species) coming under 7 genera have been made. Seven of these are new counts and in two others the numbers observed here differ from previous reports.
Detailed karyomorphological analysis of a species (Viscum capitellatum Sm.) in the family Viscaceae is reported for the first time. The exceptionally large chromosomes in V. capitellatum probably represent the largest chromosomes in dicot angiosperms. The chromosome number of the species has been found to ben= 10 and 2n = 20. One pair of the chromosomes is heterochromatic. It is suggested that unequal crossing over of a segment between the homologous chromosomes has resulted in one duplicate chromosome and the other deficient.
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