Developmental morphology of the flower of Anaphyllopsis americana and its relevance to our understanding of basal Araceae

Abstract

The inflorescence of Anaphyllopsis americana (Engler) A. Hay consists of more than 100 flowers arranged in recognizable spirals. Each flower has four broad tepals enclosing four stamens that are not visible prior to anthesis. The unilocular ovary contains one ovule and bears a discoid stigma. The floral primordia are first initiated on the upper portion of the inflorescence. At an early stage during their development, the floral primordia have a circular shape. Two lateral tepals are initiated nearly simultaneously followed by two median tepals. After their initiation, each stamen is associated with a tepal of the same radius; the two lateral stamens are initiated first, directly opposite to the lateral tepals. The unilocular nature of the ovary is clearly visible during the early stages of development of the gynoecium. At dehiscence, anther wall raphides are present in anther locules and are mixed with pollen. The mode of floral development observed in Anaphyllopsis is similar to that reported for Anthurium jenmanii Engl. However, this similarity in mode of development may be linked to structural constraints rather than phylogenetic relationships. The presence of a few pentamerous flowers in the inflorescence of Anaphyllopsis suggests a possible relationship with Dracontium . This would be in accordance with recent molecular studies showing that Anaphyllopsis and Dracontium are closely related.