This work aims at investigating the possibility to account for the volumetric growth of a binary solid-uid mixture, within the context of biomechanical perspectives in rational mixture theories. Growth phenomena are coarsely taken into account by describing the time evolution of the solid stress-free configuration, whose introduction contributes a part of the constitutive information to the resulting dynamics, while enriching the kinematical description of the mixture. The issue of invariance requirements under changes in observer is also addressed, and some relevant constitutive implications are briey outlined.