As plants grow, leaves curl at the edges in response to self competition. Eventually a verticle leaf position is attained as mature plants press into tight chains and form mats of many floating plants. This feature distinguishes S. molesta from common salvinia, S. minima, which has branched hairs that are spreading and free at the tips. Hairs on mature leaves may be damaged and not true to type. Young, unfolding leaves will reveal fresh hairs that remain descriptive for the species.
Submersed leaves are filamentous, look like roots, and often bear chains of egg-shaped sporocarps.
Plants may demonstrate variability in the arrangement of the sporocarp chains, a function of developmental stage or a response to environmental conditions. Mature plants can produce large quantities of sporocarps that contain many sporangia, yet plants are functionally sterile. Giant salvinia reproduces very effectively through vegetative means. Stems fragment as plants mature and new plants develop from apical and lateral buds. Plants will withstand periods of stress, both low temperature and dewatering, as dormant buds.