Mariath 2015 (Conference Paper) Bromeliaceae

Embryological and anatomical features in Bromeliad Systematics

Author(s):—J.E. Mariath 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:—Plant anatomy, especially of reproductive organs, has been very important in Bromeliaceae. The analysis of ovary andovule development in the Nidularioid complex identified traits that can assist in the general delimitation of the complexand compare the characters found with the current taxonomic proposals. The number of cell layers of integuments,format of the outer integument cells and cell morphology of the nucellar epidermis in the micropyle zone, gametophyteformat and the presence or absence of a chalazal appendage were highlighted as important morphological features. Asto the ovary, the number of columns of ovules per locule, the orientation of the ovules in relation to the ovary axis, aswell as the analysis of the mesophyll morphology, where the formation of aerenchyma was observed, were considered important. This feature was a synapomorphy found for the species of the complex, and is related to the hypoxiccondition that these ovaries are subjected to. The parsimony analysis separated Canistrum from the other species ofthe complex. This result agrees with the latest phylogenies. And while Wittrockia and Edmundoa are used by someauthors as a synonym for Canistrum, in relation to the ovary and the ovule they share a greater number of characterswith other species in the complex than with Canistrum. The analysis of five genera of Tillandsioideae demonstratedthe variations in the number of columns of ovules per locule, the presence or absence of chalazal appendages andtheir dimensions and details of the development of integuments, as important taxonomic characters. Similarly thedetails of the ovule development of Billbergia nutans of the Bromelioideae subfamily underscored useful charactersfor taxonomy and identified the evolutionary scenario of such embryological characters in the family. We highlightthe first, three-dimensional analysis of a female gametophyte in monocots hoping that this approach will be furtherexplored to assist the interpretation of reproductive structures and detection of new characters. Fruit anatomy has beenused to define or solve taxonomic problems among species, genera, tribes and families in different plant groups. Theanatomy of the dehiscent fruit is closely related to the type of dehiscence. Details such as wedged macrosclereids andstriking structures of the pericarp of Bromeliaceae capsules and the U-shaped thickness of the cell wall, reported onlyfor eudicotyledonous fruit, are also shown as occurring in monocots. Based on phylogenetic proposals, the evolutionof the fruits shows a tendency to indehiscence, with a probably plesiomorphic capsule character. Finally, a partialanalysis of mature seeds of 14 species of Tillandsia and Vriesea established structural patterns of seed coat, endospermand embryo, allowing one to distinguish between these two genera. The information presented here reinforces theneed for further morpho-anatomical analyses.

Keywords:—Anatomy; Morphology; Taxonomy.