ESTABLISHMENT AND DEVELOPMENT OF A POPULATION OF ORCHIS SIMIA LAMK. IN THE NETHERLANDS, 1972 TO 1981

Abstract

Observations in chalk grassland in South Limburg, Netherlands, were made over a 10‐year period on the development of a population of Orchis simia which probably originated from a single individual. The original plant (‘mother plant’) flowered for 10 successive years and, in years when the inflorescence was not damaged by grazing animals, produced viable seed. The species is clearly self‐compatible. Juvenile plants with only one or two narrow leaves were found for the first time 4 years after the mother plant had flowered. Thereafter, recruitment to the population occurred annually, but the number of new plants in any one year was low (5 to 13). Some juvenile plants flowered 3 years after appearing above ground, while others have still to flower after 6 years above ground. Only those plants which had developed four or five leaves in the rosette with a minimum leaf area of more than 60 cm2 flowered. The height of the flowering stem and number of flowers on the inflorescence at the mother plant varied considerably from year to year but in every year it was more vigorous than the juvenile plants. New plants were also developed by vegetative means, but this method of reproduction is considered to be unimportant compared with spread by means of seeds. Copyright © 1982, Wiley Blackwell. All rights reserved