“…Ever since somaclonal variation was introduced as a novel source of variability in cell cultures for plant improvement, by , it has attracted considerable attention in non-woody species (see Bajaj, 1990Bajaj, , 1996Cullis and Greissen, 1987;Gould, 1986;Krikorian et al, 1989;Skirvin et al, 1994), as weIl as in woody plants (see Ahuja, 1987a;Chen and Ahuja, 1993;Fry et al, 1998;Michler, 1993;Ostry and Michler, 1993;. In this chapter I shall briefly examine the sources and spectrum of somaclonal variation, but focus mainly on its genetic basis and its application to forest trees.…”