BIOSYSTEMATIC STUDIES OF THE CAREX FLAVA COMPLEX I. FLOWERING

SUMMARY As a part of a broader biosystematic analysis of the NW‐European species of the Carex flava complex a comparative study was made of the flowering of C. flava, C. lepidocarpa, C. demissa and the subspecies serotina and pulchella of C. serotina . In these taxa the inflorescence develops in the same way, except the apical male spike, which in C. flava starts anthesis in its lower portion, but in all other species in the distal portion during the principal flowering period and at the other end during protracted flowering. The inflorescence is protogynous. A male spike contains florets in anthesis for several days, each individual floret coming in anthesis for one day only and producing pollen during the morning. A female floret may be in anthesis for several days. The development of the spikes in an inflorescence proceeds basipetally, but anthesis in a female spike proceeds acropetally. The development of inflorescences with an anomalous distribution of the sexes, and the flowering phenomena characteristic of hybrids are discussed separately. The flowering periods of the taxa coincide to an appreciable extent, so that hybridisation is likely to occur. Protracted or second flowering has only been observed in C. demissa and C. serotina . Only C. serotina comes into flower in the first growing season. The differences between its phenology and that of the other species may be attributable to its specific habitat. All species are anemophilous and exhibit both autogamy and outbreeding.