New chromosome counts in New Zealand species of Plantago (Plantaginaceae)

Polyploidy is common in the widespread genus Plantago, and might be especially important in the evolutionary history of native New Zealand species of the genus. To further understanding of native New Zealand Plantago, mitotic and meiotic chromosome counts are reported from 58 individuals representing most native species and subspecies, and one introduced species, complementing previous studies by extending the number of individuals and the geographic range of taxa counted. Previous counts were confirmed for most Plantago lanigera (2n = 2x = 12), all P. raoulii, P. spathulata subsp. spathulata, P. spathulata subsp. picta, P. triandra subsp. triandra and P. triandra subsp. masoniae (2n=8x=48), most P. unibracteata (2n=10x=60), and all P. sp. 'Sylvester' (2n=16x=96). Novel counts include 2n=12x=72 for four individuals identified as P. unibracteata, and 2n=48 for four individuals from Sugarloaf Pass, South Island, referred to here as P. aff. spathulata. One of the eight naturalized species, P. major, was diploid with 2n=12. These results, together with other studies, suggest that all native New Zealand Plantago have a base chromosome number of x=6 and most polyploids are allopolyploids.