Diversidade morfológica e anatômica foliar de Asteraceae em área relictual de campos arenosos e rochosos (campos rupestres)

Abstract

This dissertation consists of a single chapter aimed at the morphological and anatomical characterization of the leaf blades of an Asteraceae assemblage found in a relictual area of campo rupestre (rocky grassland). It discusses conserved traits, potential morpho-anatomical adaptations of the taxa to local edaphoclimatic conditions, and adaptive convergences among the analyzed species. Sixty-five species distributed across 11 tribes were collected; they were primarily herbaceous or shrubby in habit and grew in full sun. We identified numerous morpho-anatomical traits that may constitute survival strategies for the assemblage's taxa, such as tall, voluminous epidermal cells, thickened epidermal walls, thin cuticles, stomatal crypts, high trichome coverage, compact mesophyll, vascular bundles with perivascular fibers and lignified parenchymatous sheath extensions, and small leaves. Statistical analysis revealed a negative correlation between leaf area and the thickness of the adaxial and abaxial epidermis (and their cell walls), suggesting that, within the studied group, species with smaller leaves tend to invest more resources in their outer leaf covering. The assemblage exhibits diverse leaf traits related to survival in its habitat; some species are clearly conservative xeromorphs, while others combine different strategies. Thus, the studied assemblage displays morpho-anatomical adaptations and adjustments in functional traits that may represent responses to habitat characteristics—specifically, recurrent water scarcity due to sandy soil and high light intensity, which can also expose the plants to thermal stress.