Comparative geographical variation in seedling morphology of three closely related red mahoganies, Eucalyptus Urophylla, E. pellita and E. scias

Twenty two populations of Eucalyptus urophylla, 13 of E. pellita and two of E. scias were selected throughout the species’ natural distributions in Indonesia, Papua New Guinea and Australia, and the morphology of seedlings compared under greenhouse conditions. Leaf length, width, length/width ratio, base angle, stem shape and, to a lesser extent, intranode length provided good discrimination between species and provenances. Canonical variate analysis revealed four groups, two of which contain E. urophylla, one E. pellita and one E. scias. Wetar Island provenances formed one of the two E. urophylla groups, distinguished from the other group consisting of Alor, Adonara, Flores, Pantar and Timor provenances on the basis of narrower leaves, greater length/width ratios, more acute leaf base angles and square stems. Seedling leaves of E. pellita were generally longer and broader than the other species, with a tendency for a separation between the northern occurrences (New Guinea and northern Cape York Peninsula, Queensland) and southern occurrences (Helenvale to Rockhampton, Queensland); those from the north had smaller leaves and more distinctly square stems. E. scias is clearly distinguished by its narrower leaves and longer intranode length.