ABSTRACT
A família Amaranthaceae é formada por cerca de 2.360 espécies, 145 delas encontradas no Brasil. Cerca de 94 espécies da família subsistem em diversas fitofisionomias do Bioma Cerrado e 27 espécies aparecem em listas regionais de espécies ameaçadas de extinção. O objetivo deste trabalho foi inventariar e estudar a anatomia foliar e a morfologia de espécies da família Amaranthaceae de uma Unidade de Conservação de Alto Paraíso, GO, relacionando-as ao metabolismo fotossintético. Foram localizadas uma espécie de hábito subarbustivo (Pfaffia townsendii) e cinco espécies herbáceas (Froelichiella grisea, Gomphrena hermogenesii, G. lanigera, G. prostrata e P. gnaphalioides), a maioria demonstrando comportamento pirofítico e anemocoria, bem como sistemas subterrâneos bem desenvolvidos associados com anfiestomia foliar. A anatomia Kranz foi caracterizada em três espécies (todas do gênero Gomphrena), indicando o metabolismo fotossintético C4. Duas espécies são endêmicas da área e duas espécies são consideradas ameaçadas de extinção. Aspectos de anatomia e morfologia são discutidos em relação ao hábito das espécies, comportamento ecológico, duração das porções aéreas e significado funcional. Os dados demonstram a importância da família como indicadora da biodiversidade das áreas abertas dos cerrados e da importância da ampliação das pesquisas na Chapada dos Veadeiros, que tem potencial para o registro de novas espécies, inclusive endêmicas, dado o comportamento sazonal de algumas dicotiledôneas herbáceas e as dificuldades para localizá-las, identificá-las e coletá-las.
The Amaranthaceae family is composed of 2,360 species of which 145 are found in Brazilian vegetation. About 94 species of this family subsist in different phytofisionomies of the Cerrado Biome (a savanna-like vegetation) and 27 species are cited in Brazilian regional lists of endangered species. This work aimed to inventory and to study the leaf anatomy and morphology of the Amaranthaceae species found in one Conservation Area in Alto Paraíso, GO, relating them to the species' photosynthetic metabolism. It was found one subshrub species (Pfaffia townsendii) and five herbaceous species (Froelichiella grisea, Gomphrena hermogenesii, G. lanigera, G. prostrata and P. gnaphalioides), most of them showing pirophytic and anemocoric behavior and well developed subterraneous systems associated with leaf amphistomy. The Kranz anatomy was verified in three species (all Gomphrena genus), which indicates the C4 pathway of photosynthesis. Two species are endemic of the area (Chapada dos Veadeiros) and two are considered endangered species. The anatomy and morphology aspects are discussed in relation to the species habit, ecological behavior, life span of the aerial organs and functional data. The results indicate the Amaranthaceae importance as biodiversity indicator of open vegetation areas of Cerrado and the necessity of further research in Chapada dos Veadeiros, which has the potential to register new plant species, including endemic ones, since this work displays the seasonal behavior of some dicotyledonean herbaceous species and the difficulties to locate, identify and collect them.
ABSTRACT
The leaf structure and micromorphology characterize plant species and reflex its interactions with the environment. Leaf epidermis sculptures aid high transpiration plants on light reflection. The form and distribution of epicuticular wax crystalloids are important to characterize the surface. Aiming to know the micromorphology and the ultrastructure of G. arborescens, G. pohlii and G. virgata, leaves of these Cerrado native species were collected in Brasília, Distrito Federal, Brazil, at the Olympic Center of the Universidade de Brasília and at Reserva Ecológica do Roncador. Leaves of G. globosa, an Indian native species, were also studied for comparison. Leaves were fractionated, fixed and treated for observation under optical and scanning electron microscope. A description of the leaf epidermis is provided, alo ng with some quantitative data to help the species taxonomy and support future studies on their physiology: all species are amphistomatic and have Stomatal Index between 7.27 and 18.99. The Gomphrena spp. studied have epicuticular wax platelets and wax sculptures over their larger trichome, which are relevant for their taxonomy. Over the Cerrado species cuticle, epicuticular wax is damaged by fungi hyphae development. The presence of epicuticular wax on Gomphrena spp. leaves corroborates the phylogenetical alliance between Amaranthaceae and Chenopodiaceae.