On culturing the young anther of a plant a botanist got a few diploid plants alongwith haploid plants. Which of the following might have given the diploid plants

On culturing the young anther of a plant a botanist got a few diploid plants along with haploid plants. Cells of anther wall might have given the diploid plants.
The anther wall contains four layers called the epidermis, endothecium, middle layer, and tapetum, and all of them are diploid and produce diploid plants when cultured on artificial media.
Inside anther locules, pollen mother cells undergo meiosis to form microspores enclosed in the tetrad. After release, microspores further develop into mature pollen.