Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil

摘要

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil (Quesnelia strobilispica Wawra and Wittrockia gigantea (Baker) Leme) and a forest fragment located within Born Sucesso Farm, Vicosa, Minas Gerais, Brazil (Billbergia euphemiae E. Morren and Bromelia antiacantha Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of B. euphemiae and W gigantea showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species B. euphemiae and the terrestrial species Q. strobilispica have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species Bromelia antiacantha and the epiphytic species W. gigantea also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect micro-climatic conditions under which these species occur or genetically fixed characteristics.