Pachystegia rufa and allied rock daisies

This report presents preliminary information on Pachystegia rufa and allied species; the so-called Marlborough rock daisies, here referred to collectively as pachystegias. The report is based on field and experimental information gathered by the author since 1978, and additional data derived from joint studies of seed set and germination, cytology and flavonoid chemistry. Field visits have been made to many parts of eastern Marlborough and North Canterbury where pachystegias grow to determine the number of taxa involved and their habitats, ecology and lifestyle. Additional information has been gathered from herbarium specimens, both within New Zealand and abroad. Detailed studies of the biology and character states of the various taxa have been carried out on plants cultivated in the experimental facilities of Landcare Research at Lincoln. More recently plants held at Lincoln and in the Christch-urch Botanic Gardens have been used for further taxonomic comparison and studies of floral biology. Only one species of Pachystegia, P. rufa is listed among the threatened and uncommon plants of New Zealand, where it is classed as a "Declining" species. The more obvious threats to P. rufa and allied species include roadworks, quarrying, herbicide application, wilding trees, broom infestations, and animal browsing. Of more recent concern, especially for recruitment and sustainability of pachystegias, is the spread of aggressive introduced grasses and herbs which threaten to occupy and dominate crevices and niches in rupestral habitats.