Chromosome number and polyploidy in Spilanthes Jacq. (Asteraceae: Heliantheae)

Abstract

Spilanthes Jacq. represented by eight species in Kerala state of India is distributed in a wide range of habitats. Many members of the genus are medicinally important. Present study was conducted to find out the chromosome number and ploidy level of existing eight confusing species of Spilanthes collected from different parts of Kerala. The chromosome number varied from 2n = 52 to 2n = 78 with majority of species concentrated in the number 2n = 52, somatic variants were seen in S. ciliata (2n = 78) and S. tetralobata (2n = 65 and 78). This is the first report of chromosome numbers found in three species, S. ghoshinis, S. tetralobata and S. vazhachalensis. The incidence of polyploidy is very much striking in the genus Spilanthes. The members studied showed hexaploid, pentaploid and tetraploid condition, with the basic chromosome number X = 13. Among different species of Spilanthes, S. ghoshinis, S. paniculata and S. uliginosa are tetraploids, S. vazhachalensis is pentaploid, S. calva along with S. radicans are hexaploids. However S. ciliata showed tetraploid and hexaploid plants. S. tetralobata showed tetraploid, pentaploid and hexaploid plants in their natural habitat. The present study confirmed the secondary basic number X = 13 in this genus.