A scanning electron microscope study of cotyledon development inPinus caribaeaMorelet, with some remarks on the relationships between polycotyly and dicotyly

Abstract

SummaryPhylogenetical relationships between dicotyly and polycotyly are still contentious matters today. During cotyledon initiation in Pinus caribaea, one passes from four cotyledonary primordia (set up successively two by two), to six or eight cotyledons (occurring from primordia “division”). These results invite a reconsideration of former conclusions based on observing ontogenesis in polycotyledonous Gymnosperms. They tend to prove that polycotyly in fact constitutes a derivative condition. This conclusion is compared with those drawn from paleobotany and anatomy, as well as from cladistics.