Ecological aspects of the floral phenology of the cork-oak (Q suber L): why do annual and biennial biotypes appear? JA Elena-Rossello, JM de Rio, JL Garcia Valdecantos and IG SantamariaAnn. For. Sci., 50 Supplement (1993) 114s-121sDOI: https://doi.org/10.1051/forest:19930710