The value of pollen morphology in the classification of the genus Hoheria
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
The primary aim of this research was to determine the value of pollen morphology in the classification of Hoheria glabrata and H. Lyallii, two species of small tree which grow in the South Island mountains of New Zealand. The two taxa appear very similar in general morphology, which has led to speculation over their status as distinct species. The secondary aim was to briefly study the pollen of the remaining six taxa of the genus Hoheria to determine how useful pollen morphology may be for their classification. To fulfil these aims specific objectives were defined. These were to determine: (1) The level(s) at which pollen variation was significant within and between individual trees. (2) The possibility of grouping variations in pollen morphology into distinct types. (3) The way in which morphological types could be related to taxonomic schemes for the Hoheria genus. (4) If these pollen types could be correlated with climatic or other environmental parameters. Extensive field sampling of H. glabrata and H. Lyallii pollen was carried out, while the remaining six taxa were sampled from herbarium sheets. The pollen was examined under the scanning electron microscope, where it was photographed and then measured for specific grain and spine characteristics. The data was analysed by computer using analysis of variance and discriminant analysis Significant variation of the pollen characters was found within and between individual trees of H. glabrata and H. Lyallii, but not between the two taxa. None of the eight taxa of Hoheria could be separated using pollen morphological characteristics. Therefore pollen cannot be regarded as a reliable taxonomic character to differentiate either Quaternary or modern pollen of the genus Hoheria. Consequently the question of whether H. glabrata and H. Lyallit are distinct species remains unresolved.