The Author concludes, in this contribution, the estudy he has been making since 1943, on the biological and ecological comportment of Apinagia Accorsii Toledo an of Mniopsis Glazioviana Warmg., Podostemonaceae wich are found attached to the rocks of Piracicaba Fall (Piracicaba, S. Paulo, Brazil). During the flood period, from October until March, the especies mentioned perform their vegetative development. Apigia Accorsii emittes stolons wich produce, laterally, rhizomes: besides, the still alive parts of the remaning rhizomes are regenerated. Mniopsis Glazioviana emittes hemicylindrical roots, the radicular buds of wich are capable of developing into new plants. For both especies, the germination of seeds may be effected in the following substrata : placents, capsules and pedicels of the fruits, vegetative residues and rhizomatic matter of Apinagia. Dehiscence of fruits takes place in contact with the air. Seeds adhere to the above mentioned substrata by means of a mucilage resulting from the transformation of its external tegument, in contact with water. The seedlings have no main root. A large number of root hairs develop around the hypocotyl; their function is fixation. The attachment of the plants to the rocks is made by means of root hairs and "haptera". The tranfer of young plants, which develop in the placents, capsules and fruits pedicels, etc., to the rocks takes place when they grow heavy enough as to bend the pedicels. The fruits and their parts contitute the best mean for the survining of the species in its habitat, for they are the only organs which stick to the rocks, after the complete destruction of the plant's bodies. The vegetative development is performed exclusively under water, while the floral cycle takes place as soon as the plants come in contact with the athmosphere, when they flower and fructiffy rapidly.