Root anatomy of 27 specimens of 13 species of Actinocephalus (Koern.) Sano were studied. All species occur in Brazilian rupestrian fields. All species present roots with uniseriate epidermis, isolated or agregated root hairs; isodiametric cortical cells, except in the innermost layers that are smaller and present thickened wall cells; uniseriate radially elongated endodermis, with parcial or totally thickened wall cells; uniseriate pericycle, with thin or thickened wall cells; and vascular cylinder with metaxylem in central position. Cortex with isodiametric cells, without aerenchyma; epidermis and cortical parenchyma with intracellular protuberances associated with fungi; are consistent to the recent genus circunscription. Althouth a lot of species are also known for growing in damp habitats, near to small rivers, their roots present anatomical features similar to that Eriocaulaceae species that occur in dry soils.
root; Actinocephalus; new genus; monocotyledons
