Pollen, Tapetum and Orbicule Development in Modiolastrum malvifolium (Malvaceae)

Although orbicular functions are still a matter of debate, they are considered by most authors to be exclusively formed by a secretory tapetum. However, the presence of orbicules on a peritapetal membrane associated with a plasmodial tapetum has been described for Abutilon pictum (Malvaceae) in a previous study. Thus, studies on other species of Malvaceae are necessary to corroborate the presence of such bodies in other members of the family. Pollen and microsporangium development of Modiolastrum malvifolium has been studied in this work.