New Zealand's pteridophyte flora - plants of ancient lineage but recent arrival?

Brownsey, P J. (Museum of New Zealand. P.O. Box 467, Wellington, New Zealan d). New Zealand's pteridophyte flora-plants of ancient lineage but recent a rrival? Brittonia 53: 284-303. 2001.-A hypothesis is presented that most pt eridophytes arrived in New Zealand relatively recently, by long-distance di spersal. The flora comprises 194 native species, of which 89 (46%) are ende mic and 105 (54%) are widespread. Of the latter, 90% are shared with temper ate Australasia, 53% with tropical regions, 14% with temperate southern Afr ica and 13% with the circum-Antarctic islands and South America. New Zealan d has undergone such dramatic changes in location, land area, and topograph y since initial separation from Gondwana 85 Ma that it seems improbable tha t the 95 species shared with temperate Australasia could have remained cons pecific throughout that time. Modem fossil and molecular evidence strongly suggest that many families of ferns had not even evolved prior to separatio n, and palynological evidence from New Zealand indicates that 78% of pterid ophyte genera first appeared there only after separation from Gondwana. Pre sent-day distributions in New Zealand suggest that ferns have greater dispe rsal potential than flowering plants, and that pteridophyte distributions a re more heavily influenced by temperature, rainfall, and geothermal activit y than by geological history. Most endemic pteridophyte species have a pred ominantly southern distribution pattern and are characteristic of cool, low land to montane forest. Pteridophytes in the nor-them part of New Zealand s how a lower level of endemism than elsewhere and tend to be widespread spec ies that have arrived from temperate Australasian and tropical regions. The re is also evidence that at least some pteridophytes have migrated from New Zealand to Australia. It is suggested that the hypothesis of long-distance dispersal of pteridophytes across the Tasman Sea could be tested by molecu lar techniques.