The seeds always know best

Abstract

The New Zealand woody plant flora differs from those of temperate Northern Hemisphere regions by having: a very high proportion (70% cf. 17-47%) of tree species (but lower proportions of shrubs and vines) with fleshy fruit; a relatively low proportion of seeds with overwinter dormancy; and relatively few species that form long-term (i.e., 1 year or longer) seed banks. These differences are ascribed to the effects of: the phylogenetic history of the respective floras, with most tree species in New Zealand being closely related to tropical taxa; the evolution here, under isolation, of a small but effective group of seed-dispersing birds; and the selective influences of much more severe Quaternary climatic conditions in the north, affecting both the drying of fruit and seeds and seed dormancy properties. As a consequence, a New Zealand perspective on germination delay phenomena in seeds must differ, somewhat, from the Northern Hemisphere bias that is so evident in the plant physiological and ecological literature about seeds.