FLOWER AND INFLORESCENCE DEVELOPMENT IN MONTRICHARDIA-ARBORESCENS (L)SCHOTT (ARACEAE)

The spadix of Montrichardia arborescens contains unisexual flowers wit hout a perianth. The pistillate flowers occur in the basal portion, an d the staminate flowers are in the apical portion of the inflorescence axis. In some spadices the zone between male Bowers and female flower s contains vestigial flowers. A morphological gradient seems to be app arent in the intermediary zone: the portion of the bisexual flower fac ing the staminate zone possesses staminate characters (stamens), and t he portion facing the pistillate zone possesses pistillate characters (aborted gynoecium). The floral primordia appear in successive alterna ting rows producing parastichies (helices) around the spadix. The numb er of opposed contact parastichies can vary depending on the form of t he inflorescence and on the number of flowers produced, Pistillate and staminate flowers are inserted in the same contact parastichies along the inflorescence, with no discontinuity among the female zone, the b isexual zone, and the male zone. On the same parastichies, one can obs erve a continuum from the lower to the upper part of the young inflore scences.