Volume 17, Issue 4
April 1943, pages 97-132
pp 97-117 April 1943
pp 118-132 April 1943
Somatic chromosome numbers have been determined mostly for the first time for 24 species, spread over 7 genera.
Chromosome complements inZingiber officinale, Z. zerumbet, Z. cassumunar, Costus igneus andC. discolor have been analysed.
The basic numbers 6, 9, 11, 12, 13 and 21 are suggested for the generaKœmpferia, Costus, Zingiber, Alpinia, Hedychium, Elettaria, Globba and Phœomeria. 6 appears to be the primary basic number, the others representing secondary balances of this primary number.
A biphyletic origin is suggested for the species ofHedychium one from the basic number 9 and the other from the basic number 13.
Speciation in this family has been found to be due to polyploidy, aneuploidy and structural changes.
The 42 chromosomed members of the genusCurcuma are believed to be arnphidiploids derived from a cross between 12- and 9-chromosomed ancestors. It is also suggested thatCurcuma longa is likely to be a triploid form of C.aromatica.
The distinctive nature of the chromosomes of Costus, their morphology and number, would appear to justify the separation of this genus into a tribe or sub-order.