9 - Multiplications of floral organs in flowers: a case study in Conostegia (Melastomataceae, Myrtales)

Summary

Introduction

The genus Conostegia (Miconieae, Melastomataceae) includes shrubs and trees distributed in the Caribbean, Mexico, Central America, N Andes and Brazil (Schnell, 1996). At present, Conostegia contains about 40 species (Schnell, 1996; Mabberley, 1997), although over 100 names have been applied to the genus in the past. However, the elevated number of species has been explained as a probable misinterpretation of the intraspecific variation that occurs in some species (Schnell, 1996).

The name Conostegia, which is derived from the Greek words κονοσ = cone and στεγοσ = roof, was chosen by D. Don (1823) for grouping species characterized by flowers having their sepals fused into a cone-shaped calyptra (Fig 9.1 A–D). Despite the fact that a calyptrate calyx is present in other genera of the Melastomataceae, such as Bellucia, Blakea, Centronia, Henriettea, Llewellynia, Miconia and Pternandra (Schnell, 1996; Penneys et al., 2010), the peculiar calyx of Conostegia has long been regarded as a useful character for segregating Conostegia from other non-calyptrate species of Melastomataceae (Don, 1823). Species of Conostegia are immediately recognizable by the character combination of terminal inflorescences, flowers often multistaminate, calyx clearly circumscissily dehiscent at anthesis, anthers isomorphic and unappendaged, ovary inferior and berry fruits (Almeda, 2008).