Estudio morfoanatómico y micrográfico de Pluchea microcephala R. K. Godfrey (Asteraceae) empleada en medicina tradicional argentina

pluchea microcephala ("cuatrocantos", "lucera") is a perennial native species from northern argentina, bolivia and nw of perú, commonly used to treat digestive and hepatic disorders in humans. it grows in humid and saline soils, and bordering watercourses. morphoanatomical characteristics of leaves, stems and capitula have been studied in order to determine the main diagnostic characters for the identification of this species. light microscope observations were carried out on herbarium specimens, dissociated material, and serial transverse sections of restored herbarium material. leaves are decurrent, anfistomatic, with eglandulate septate-flagellate trichomes and glandular trichomes with a entire biseriate stem. the mesophyll is isobilateral with lipidic globules. stems are winged, epidermal tissue has stomata and trichomes similar to those present in leaves; the cortex is composed of aerenchyma and the eustele has collateral vascular bundles and parenchymatous or hollow pith. capitula are disciform, heterogamous, grouped in dense apical corymbs, with flared involucres formed by few rows of phyllaries. outer purplish flowers are numerous and present a filiform 3-lobulate corolla. central flowers, which occur in low numbers, have a tubular 5-lobulate corolla. the cypsela has longitudinal ribs and pappus is formed by a row of hairs. this investigation reports the first anatomical description of the species. the characters described result in an important quality control tool to identify this species.