A New Basic Chromosome Number in the Family Fagaceae

Abstract

CHROMOSOME numbers have been determined previously for some 58 species in the family Fagaceae, covering the three genera of the northern temperate zone, Quercus, Castanea and Fagw^1–3. These determinations are uniformly 2n = 24, the Fagaceae resembling many other families of woody angiosperms in this stability of chromosome number. The southern beech genus, Nothofagus, with some 20 species distributed in temperate South America, New Zealand and Australia and extending up into New Guinea and New Caledonia, was at one time included in Fagus, and it is more closely allied in features of floral and pollen morphology to Fagus than to any of the other genera in the family^4–6. The four New Zealand species are all endemic and are the principal evergreen hardwoods in much of the indigenous forest. They include representatives of two of the sections into which the genus is divided: in the fusca section, N.fusca, N.truncata and N.solandri, all of which hybridize freely in the wild, and in the menziesii section, N.menziesii, which is not known to cross with any of the other species.