Contribution to the embryology of Potamogeton L. (Alismatales: Potamogetonaceae)

Potamogetonaceae currently comprises four genera, including Potamogeton, a near cosmopolitan genus of about 100 species. The historical circumscription of this family is controversial, resulting in fragmentary information on the morphology and anatomy of its genera. The aim of the present study was to investigate the anther and ovule development in three species of Potamogeton in order to clarify the embryological features of this genus. The majority of embryological characters were constant among the three species studied and are in accordance with previous reports. In addition, some new and complementary characteristics of Potamogeton embryology are highlighted, including: monocotyledonous-type of anther wall development and carpels bearing a single ovule that develops a Polygonum-type of megagametophyte. A fail in the micropylar dyad to divide is confirmed as the cause of megaspore triads. The developmental sequence of the ovule confirms its campylotropous curvature.