Marcos et al. 2015 (Conference Paper) Bromeliaceae, stigma

Stigma Development in Bromeliaceae

Author(s):—D. Marcos, W. França, A. Costa & K. de Toni in Benko-Iseppon, A.M.; Alves, M. & Louzada, R. (2015) An overview and abstracts of the First World Congress on Bromeliaceae Evolution. Rodriguésia 66(2): A1-A66.

Publication:— (2015).

Abstract:—Bromeliaceae consists of 58 genera and 3,352 species, divided into eight subfamilies; which show wide morphological and taxonomical diversity, thereby hindering generic and specific delimitation. Among the morphological characters, the floral are the most prominent, because the ontogeny of the stigmas is relevant to understanding evolution of the subfamilies. Until now, six stigma types have been described for the family: conduplicate-spiral, simple-erect, cupulate, convolute-blade, coralliform and tubolaciniate. In order to contribute to the phylogeny of the Bromeliaceae, this study aims to describe stigma development, in attempt to better classify them. For this, flower buds and flowers from 36 species of Bromeliaceae were collected. The analysis indicated four stigma types among the studied samples. For all species, the upper gynoecium begins with the simultaneous settling of its three primordium carpels, which are initially fused only at the basalportion. Upon carpel maturation, variations in the development of stigmatic lobes were identified, typifying the different kinds of stigma. Initially, in the conduplicate-spiral, the stigmas conduplicate and then spiral among themselves. This last stage becomes even more conspicuous near floral anthesis. In this stage one can also notice some specifics among the species: existence of papilate, crenate or laciniate margins. This type was described for Pitcairnioideae and Bromelioideae species. In the simple-erect type, the stigmatic lobes are erect and with papillae during all development stages, but light twists in the lobes were noticed in some species. This stigmatic type is specific of Tillandsia. In the convolute-blade, during early stages, one may observe the irregular growth of irregular stigmatic margins, and then conduplication of lobes, which becomes more prominent upon the maturation of the structure. At the intermediate stage, papillae appear on the lobes. Convolute-blade is homogenous for Vriesea, due to the variations observed in the density of papillae and merging of stigmatic lobes; this type was divided into 3 subtypes. In addition, a new stimagtic type is described, the Alcantarea, described for the genus with the same name, in Tillandsioideae. In earlier stages, the Alcanterea-type is similar to simple-erect, but after maturation, one may observe twists on stigmatic apices and on the apical portion of the style, which intertwine but do not merge. Furthermore, one may observe the appearance of papillae, which stretch themselves until floral anthesis. Thus, ontogenetic studies show great relevance for improving classification of the genera and species within Bromeliaceae. From the ontogeny of the stigmas, it is possible to suggest that the ancestral type in Bromeliaceae is conduplicate-spiral, which is common in all subfamilies, except Tillandioideae. A large variation regarding the types was observed, with records of simple-erect, convulote-blade and Alcantarea-type. Ontogenetic studies helped for understanding stigma evolution within subfamilies from phylogenies.

Keywords:—Bromeliaceae; Stigma; Ontogeny.