Seed size and shape and persistence in the soil in the New Zealand flora

Seed size and shape predict seed persistence in the soil for British and Ar gentinian herbaceous plant species. Those species with small, rounded seeds tend to have persistent seeds while those with larger, more elongate or fl attened seeds usually lack persistence. It has been suggested that the mech anism underlying this pattern maybe ease of burial, as small, rounded seeds are incorporated into the soil more easily than large, elongate or flatten ed seeds and are therefore less likely to be eaten by seed predators. We te sted whether seed size and shape were related to persistence in the soil fo r 47 species native to New Zealand forests. There was a tendency for specie s with persistent seeds to have smaller seeds than species with transient s eeds. However, species with large and/or elongate or flattened persistent s eeds were relatively common. This indicates that seed size and shape are no t related to persistence in New Zealand in the same way as in Britain and A rgentina. A similar negative result has been found in Australia. The underl ying cause of the patterns observed is unlikely to be ease of burial, since incorporation of seeds into the soil is likely to operate in all countries in a similar manner on seeds without specialised seed burial mechanisms. D ata from all four floras studied to date also suggest that species with sma ll, rounded seeds that do not germinate immediately must have the ability t o survive periods of burial.