Phénologie de la floraison de populations diploïdes et tétraploïdes d'Anthoxanthum alpinum et d'Anthoxanthum odoratum
The phenology of flowering was studied in an experimental garden, on diploid and tetraploid populations of Anthoxanthum alpinum A. & D. Löve and of A. odoratum L. of central and southern Europe and also in situ in a contact zone between diploid A. alpinum and tetraploid A. odoratum. In the experimental garden, the phenological parameters were studied at the individual level (onset of flowering) and at the population level (dates on which each population showed opened anthers for the first time on 40, 50, 60, 70, or 80% of the plants). Anthoxanthum alpinum flowered earlier than A. odoratum, regardless of the respective ploidy level of the two taxa. The average time lag between the appearance of the stigma and that of the stamens was about 2 days for the two A. alpinum taxa and 6 days for those of A. odoratum. Flowering was spread over the longest period for the tetraploid A. odoratum, which shows the great phenological variability of this taxon. The in situ study confirms the precocity of A. alpinum. The phenological differentiation within this polyploid complex probably coincides with the individualization of the two diploid taxa but precedes their respective polyploidization phases.