Cytotaxonomy of Amaryllidaceae

Chromosome numbers are now known for about 46 genera in the family Amaryllidaceae. The lowest basic number has been found to be 5 and the' highest 30. Besides these two, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 19, 23 and 29 have also been encountered of which 11 is found in majority of the genera. In a number of genera the derivation of one basic number from the other has been established. In the genus Allium largest number of species have been studied cytologically. The next largest is Narcissus followed by Zephyranthes, Crinum, Hippeastrum and Lycorisin that order.

B or supernumerary chromosomes have been observed in Agapanthus, Allium, Crinum, Cooperia, Haemanthus, Hippeastrum, Lycoris and Narcissus.

In this family repatterning of chromosomes through inversions (both para afid pericentric), translocation, polyploidy (eu-, aneuo-, hetero-, auto-, and allopolyploidy) and hybridization have played prominent role in chromosome number evolution, karyotype alteration and specisvtion. In addition to this, gene mutation has also played significant part in speciation. Ready vegetative propagation has helped in maintaining sterile hybrids and those forms with numerical and structural changes of chromosomes. Apomixis has also been responsible in chromosome number evolution in some genera.

A consideration of taxonomic work done in Amaryllidaceae points out that Hutchinson's system of classification, based on the umbellate inflorescence rather than on the position of the ovary, has been found to be more phylogenetic but the amendments proposed by several workers for changes in tribal and generic level could be taken into consideration and in some cases may be justified.