A woody plant is a plant that produces wood as its structural tissue. Woody plants are usually either trees, shrubs, or lianas. These are usually perennial plants whose stems and larger roots are reinforced with wood produced from secondary xylem. 

The medium defined by Gresshoff and Doy is developed for growth of haploid callus and plants of Arabidopsis thaliana cultured from the diploid anthers. The anthers were removed during the late prophase of meiosis, selecting a genotype favouring callus formation from dividing sporocytes on a high auxin - low kinetin concentration in a fully defined medium. Further differentiati-on was induced by transfer to a low auxin - high kinetin medium with a light-dark cycle. This medium has been used for haploid plantlet production in tomato, barley, and grape.