Inter‐and intraspecific variation in seed mass in seven species of umbellifer

Abstract

Patterns and causes of inter‐and intraspecific variation in individual seed mass were‐investigated in three prairie and four woodland species of perennial umbellifer. Except for Cryptotaenia canadensis, seeds from woodland species were significantly heavier than those from prairie species. Within species, the magnitude of variation in individual seed mass ranged from three‐to 16‐fold. All the distributions of individual seed masses for the seven species were significantly leptokurtotic and except for Osmorhiza longistylis, all were significantly skewed. Variation between plants was significant in one prairie species Oxypolis rigidior and all woodland species. Mean seed mass in a plant was significantly correlated with plant size in three species. Within plant variation in seed mass accounted for 52‐98% of total variation. No one factor consistently affected intraspecific variation in seed mass, although seed number per umbel, timing of umbel production and location of umbel were all important for at least one species. It is postulated that intraspecific variation in seed mass is the rule rather than the exception because of the influence of developmental factors such as seed number, timing of inflorescence production and location of different inflorescences. However, these factors may act in conflicting directions, making it difficult to assign causality to within plant variation in seed mass. Copyright © 1989, Wiley Blackwell. All rights reserved