Variations in the Proportion of the Sexes in the Capitulum As dioecy in Cotula occurs only in New Zealand, it is possible that some species might still be variable and show a transition from monoecy to dioecy. Already Hooker (1854), Kirk (1899) and Simpson (1952) had noted species that were not constant in this respect. Hooker (1854) in the “Flora Novae-Zelandiae” writes of the monoecious Leptinella minor, “… sometimes I find many flowers of one sex only in each capitulum, whence the plant is occasionally dioecious.” Kirk (1899), describing Cotula pulchella, which is dioecious, says, “Heads occasionally slightly heterogamous, one or two female florets being found in the outer row of male florets and more rarely a male floret in the centre of the female head.” In 1952 Simpson described a new variety of the dioecious Cotula pyrethrifolia which he termed var. robusta. He notes that, “The heads in both the species and the variety are not uncommonly bisexual in irregular pattern. In some heads the phenomenon appears to be due to some distortion, in others no distortion is apparent.” Some of the other species were investigated to see if they showed similar variation. (1) Monoecious Species (A) Cotula Haastii Heads were collected, one from each plant, from a natural population of Cotula Haastii at Evans Pass, and the number of female and male florets in these heads was counted. (Table II.) There was no marked difference in the proportion of female and male florets in any of the heads from this locality. Table II.—Percentages of ♀ and ♂ Florets in Heads from a Natural Population of C. Haastii. Evans Pass, 27/12/55. Total Florets. % ♀ % ♂ 145 48.9 51.1 151 45.7 54.3 144 43.0 57.0 88 48.8 51.2 95 35.7 64.3 96 45.8 54.2 149 59.7 40.3 167 54.4 45.6 107 34.5 65.5 169 50.3 49.7 140 60.7 39.3 120 51.6 48.4 125 48.0 52.0 144 59.0 41.0 Mean 49.01 50.99 Standard error ±2.14 ±2.14 Variance 64.18 64.18 However, one plant of Cotula Haastii was found in a different part of Banks Peninsula, at Mt. Evans, which showed a greater proportion of male florets than was usual in the heads from the first population, and moreover this greater proportion was found in every head from this plant. (Table III.) This was an odd plant, for no others that were predominantly male were found in that area. (B) Cotula pectinata Table IV shows the percentage of male and female florets in heads from a natural population of C. pectinata.