Introduction

There is a growing awareness among plant ecologists that the size of an individual is more important in determining its behaviour than its chronological age. Rabotnov (1950) was among the first to demonstrate that in any closed community there is likely to be a distribution of plants in different age classes. He noted that there would be seedlings, juveniles, immature adult plants, reproductive plants, vegetative adult plants and senescent non-flowering plants of great age, but he was unable to identify the factors which contributed to a plant switching from a vegetative to a reproductive state. More recently, Werner (1975), Baskin & Baskin (1979) and Gross (1981) have shown that for a number of biennials a minimum size must be reached before flowering can be induced and above a minimum size the probability of an individual flowering increases directly with rosette size.

This study focuses on the behaviour of rosettes of Ophrys apifera L. over a six year period, with particular reference to the fate of rosettes (flowering or remaining vegetative) relative to their age, size and number of leaves in any particular growing season.

Site details

The study area was a gentle, north-facing slope situated in Com's Field at National Grid Reference (NGR) 52/200795, about 600 m west of Monks Wood Experimental Station. Prior to 1960, this field had been part of a mixed farm.