Many biological tissues must be structured in such a way as to be able to adapt to two extreme biomechanical scenarios: they have to be strong to resist high pressure and mechanical forces and yet be flexible to allow large expansions and growth. A part of nature's solution to this intriguing problem are the complex microstructures and microscopic (cellular) processes, that modify tissue's elastic properties. To analyse the interplay between the mechanics, microstructure, and the chemistry we derive microscopic models for plant biomechanics, assuming that the elastic properties depend on the chemical processes and chemical reactions depend on the mechanical stresses. The microscopic models constitute strongly coupled systems of reaction-diffusion-convection equations for chemical processes and equations of linearised elasticity for elastic deformations. Multiplicative decomposition of the deformation gradient into elastic and growth parts is used to model growth of a biological tissue. To analyse the properties and behaviour of plant tissues, the macroscopic models are derived using homogenization techniques. Numerical solutions for macroscopic models demonstrate the impact of the microstructure on tissue deformations and growth.