The grass is such a soft lively ground. For the surya namaskaras and for the standing sequences no mat is necessary. For the sitting poses it's a bit too wet. Also the vinyasas wouldn't be easy on the grass. Nevertheless to practice without anything is simplicity pure.
How less is still enough?
A good question.
It's playing around what can be seen on the picture, it's not a serious practice.
Tomorrow my yoga week will start again.