Poiretia tetraphylla is an erect herb to subshrub, perennial, native to Brazil, Argentina,
Paraguay and Uruguay. It is popularly known as erva-de-touro-miúda and used in traditional medicine as
tonic, in stomach disorders and verminosis. The stem is angular, striate, glabrous with copious amounts of
oblong and translucent glands. The epidermis is uniestratified and persistent, stomata well pronounced,
thick, smooth and plain cuticle and oval mucilaginous glandular formations. The cortex has parenchyma
cells, and the innermost layer is distinguished from others by having large cells with little cytoplasmic content. In this region, protecting the phloem, has a group up to six layers of sclerenchyma fibers. The central
cylinder presents vascular system of sifonestelic continuous ectofolic type. The pith is composed of
parenchyma cells with intercellular space of meatus type. The whole of these diagnostic traits are useful on
the botanical quality control of this species.Colegio de Farmacéuticos de la Provincia de Buenos Aire
