Developmental Morphology of a Dimorphic Grass Inflorescence: The Brazilian BambooEremitis(Poaceae)

Abstract

Premise of research. The highly specialized grass inflorescence varies with respect to phyllotaxis, with the reproductive meristem forming primary lateral branches that are either spirally arranged or distichous. The Brazilian bamboo Eremitis is highly unusual in that it has a dimorphic inflorescence, typically composed of an apical gynecandrous whorl of both male and female spikelets and basal whorls of male spikelets. Although not closely related to them, Eremitis shares some structural similarities with some early-divergent grasses.Methodology. We use SEM and LM to describe the development of the reproductive structures of Eremitis to clarify our understanding of the highly specialized grass inflorescence and flower.Pivotal results. Developmental studies show that the inflorescence of Eremitis is actually partially whorled and partially distichous. The apical whorl is abortive. The female spikelet is not terminal on the axis, in contrast with the majority of grasses. All the male spikelets are disticho...