Guarçoni et al. 2015 (Conference Paper) Dyckia, leaf

Leaf anatomy of species of the Dyckia (Bromeliaceae): D. saxatilis complex

Author(s):—E. Guarçoni, A. Azevedo & A. Costa 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:—Dyckia Schultes & Schultes f. comprises 163 species occurring in all regions of Brazil as well as neighboring countriessuch as Argentina, Bolivia, Paraguay, and Uruguay. One hundred and forty species have been recorded in Brazil, 127being unique to that country and distributed in five phytogeographical regions: Cerrado (80 species), Atlantic Forest(36), pampa (20), Caatinga (10), Amazon (4), and Pantanal (3). The genus shows uniformity of its floral characters butintraspecific variability of its vegetative characters ? making the delimitation of species and their correct identificationdifficult. The hypothesis of a recent explosive radiation of Dyckia may explain some of the difficulties encountered indistinguishing consistent morphological characters that are taxonomically useful for distinguishing its species, evenwith complete and fully documented specimens in hand. We analyzed 15 populations with a total of 11 species plus anadditional morphospecies of the genus Dyckia occurring in different phytogeographical formations. The vouchers weredeposited in the VIC herbarium at the Federal University of Viçosa, in Minas Gerais State, Brazil. The anatomical analysesof the mid-regions of the leaves from at least three individuals of each species in each natural population, which werecollected in the outer region of the rosette; these were fixed in FAA50 and preserved in 70% ethyl alcohol. Cross-sectionsof the mid regions of the leaf blades were made and the sections clarified using a 20% sodium hypochlorite solution,washed, and subsequently stained with 1% astra blue and 1% aqueous safranin. Semi-permanent slides were preparedusing 50% glycerin as a mounting medium. Observations and photographic documentation were made using a lightmicroscope (Olympus model AX70TRF, Olympus Optical, Tokyo, Japan) with a U-Photo system with a coupled digitalcamera (Zeiss AxioCam HR3, Zeiss, Göttingen, Germany) using Axion Vision software, at the UFV Plant AnatomyLaboratory. The leaf structures of all of the Dyckia taxa analyzed in this study followed the general pattern described forthe family, with: peltate scales on the leaf surfaces (sometimes both surfaces), epidermal cells with silica bodies on bothsides, stomata restricted to the abaxial surface, the hypodermis differentiated into mechanical and water-storage tissueson both leaf surfaces, and vascular bundles distributed over a range. Some taxa showed variations in these anatomicalstructures, indicating important anatomical characters that can be used for distinguishing the species: the number ofsclerenchymatous hypodermal layers, the positions of the chlorophyll parenchyma cells, type of channel cells in theaerenchyma, idioblast positions, arrangements of the vascular bundles, undulating adaxial and abaxial surfaces, numbersof cells in the pedicle, and the proportion of the adaxial face in relation to the abaxial face.

Keywords:—Poales; Anatomy; Dyckia.