Anatomy of fleshy fruits in the monocots

PREMISE OF THE STUDY: An anatomical and developmental study of distantly related fleshy fruits in the monocots was undertaken to better understand the evolution of baccate fruits in the monocot clade as a whole. We studied 14 species with fleshy fruits spanning the Alismatales, Arecales, Asparagales, Commelinales, Dioscoreales, Liliales, and Poales to determine various mechanisms through which baccate fruits attain fleshiness at maturity. METHODS: Flowers and fruits of various stages were collected, sectioned, stained, and examined using light microscopy and scanning electron microscopy. KEY RESULTS: Three basic pathways for attaining fleshiness were identified within the species examined (true berries, with a uniform pericarp; typical drupes, with an endocarp differentiated by the presence of stony pyrenes; and specialized drupes, involving mesocarp and endocarp differentiated by stone pyrenes). Furthermore, developmental characters differentiating basic fruit types were identified. CONCLUSIONS: Fleshy fruits in the monocots do not develop through a single shared pathway, indicating that fleshiness has evolved multiple times within the clade.