Morelli 2015 (Conference Paper) Bromeliaceae, leaf

Leaves of Bromeliaceae from the Brazilian Chaco: morphological and anatomical features of six species

Author(s):—M. Morelli, A. Costa & R. Arruda 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:—The Bromeliaceae family comprises about 3,140 species distributed in eight subfamilies with epiphytic, saxicolous or terrestrial species, inhabiting different vegetation types in South America. Some species live in humid forests and others are found in arid zones and present anatomical and morphological frameworks that enable them to occupy the various microenvironments. In this study we investigated the leaf anatomy of six species of Bromeliaceae -Aechmea distichantha Lem., Bromelia balansae Mez, Dyckia ferruginea Mez,Encholirium lymanianum E. Pereira & Martinelli, Tillandsia duratii Vis. and Tillandsia tenuifolia L., aiming to identify the anatomical features associated with different Bromeliaceae habitats in Brazilian Chaco Forest fragments in Mato Grosso do Sul state (Brazil), where the plants undergo extensive water limitation due to seasonal rains. The leaves are rigid, succulent and have an opaque surface due to the presence of scales; some of them have rigid spines on the margin. All species investigated presented anatomical features important in water retention. A thin, external cell wall and cuticular layer was observed, but internally, the epidermal cell walls are thick and strongly lignified as in Bromelia balansae and Dyckia ferruginea. The anticlinal cell wall is extremely sinuous; the epidermal cell lumen is reduced and has a spherical silica body, most remarkably in Dyckia ferruginea, Aechmea distichanta and Bromelia balansae. Peltate multicellular trichomes (scales) wereobserved on both leaf surfaces, but are more frequent over stomata apertures. The stomata are in rows, and could be located in grooves, under the level of the other cells, thus avoiding water loss by transpiration, as in Encholirium lymanianum and Dyckia ferruginea. Under the epidermis a mechanical hypodermis, consisting of lignified and rigid cells are detected in all species, less developed only in Tillandsia species. The leavesare strongly succulent and the water storage parenchyma could be colorless or present chloroplasts. Collateral vascular bundles surrounded by a parenchymatous sheath and fiber caps constitute the vascular and support system. The anatomical features recognized could be related to different biotic and abiotic stresses acting on Chaco vegetation, such as extreme temperature range, intense light, herbivory, nutritional deficiency and seasonal availability of water playing an essential role in allowing species to occupy a dry environment.

Keywords:—Sclerified Tissues; Succulent Leaves; Xeromorphics.