REPRODUCTIVE-BIOLOGY OF PETROCOPTIS-CRASSIFOLIA ROUY (CARYOPHYLLACEAE), A CHASMOPHILOUS ENDEMIC PLANT OF THE CENTRAL PYRENEES

The reproductice biology of Petrocoptis crassifolia Rouy (Caryophyllac eae), an endemic plant of the Central Pyrenees (Spain), was studied. I ts nectariferous flowers show an ultraviolet pattern in the corolla an d an incipient zygomorphism in the arrangement of petals and stamens. P. crassifolia may produce seeds by autogamy but in smaller numbers th an when it is pollinated by insects (mainly Hymenoptera). The fruit-se t ranges between 43-80%, depending on the years and populations studie d. Fruits develop towards the rock face, and seeds exhibit myxospermy; both these traits are adaptations that facilitate the deposition of s eeds in rocky substrata. Survival of the seedlings in rocky fissures a t the end of the first year is 10%. Reproductive traits suggest that t his species is well adapted to its habitat, and that it is not endange red. Its rarity seems to be associated mainly with a lack of dispersal mechanisms for colonizing suitable but remote habitats.