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Ann Bot. 2012 Jan;109(1):135-44. doi: 10.1093/aob/mcr241. Epub 2011 Sep 20.

A comparative survey of floral characters in Capanemia Barb. Rodr. (Orchidaceae: Oncidiinae).

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  • 1Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Departamento de Botânica, Programa de Pós-graduação em Botânica, Av. Bento Gonçalves 9500, RS 91501-970, Porto Alegre, Rio Grande do Sul, Brazil. crbuzatto@gmail.com

Abstract

BACKGROUND AND AIMS:

Capanemia Barb. Rodr. comprises seven species that mostly inhabit the Brazilian Atlantic Rain Forest domain. The genus currently consists of two sections: Capanemia Cogn. and Planifolia Pabst, distinguished on the basis of leaf shape. We compare the floral morphology and anatomy of all species to determine whether separation into sections is supported by floral characters.

METHODS:

Both fresh flowers and herbarium specimens were investigated, and column and pollinarium features, together with the presence or absence of floral rewards, recorded. Anatomical features were examined using both light microscopy and scanning electron microscopy.

KEY RESULTS AND CONCLUSIONS:

With the sole exception of Capanemia therezae, all species shared a distinctive set of floral characters. Flowers were mostly white or yellowish-white and fragrant, and column wings were positioned parallel to the labellum, concealing the stigmatic cavity. Pollinaria had proportionally long tegular stipes and clavate to reniform pollinia, whereas the labellum possessed a conspicuous indument of trichomes, but was devoid of nectar or any other secretion that might function as a food-reward. Capanemia therezae, however, was exceptional in having greenish, unscented flowers with short, rounded and divergent column wings and an exposed stigmatic cavity. Its pollinaria had proportionally short tegular stipes and round pollinia, whereas the labellum lacked trichomes. Droplets of nectar were evident on the adaxial surface of the labellum, adjacent to the callus. Floral features did not support the currently accepted sectional division of Capanemia. If ongoing phylogenetic studies demonstrate that both sections are indeed monophyletic, then these taxa should be distinguished solely on the basis of foliar features.

PMID:
21937482
[PubMed - indexed for MEDLINE]
PMCID:
PMC3241572
Free PMC Article
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