The natural hybrids showed stable intermediate characteristics between the two parent species from nursery stage through to 13 years of age. E. alba had stomata on both sides of leaves while E. urophylla had stomata on the abaxial (lower) side only, and the putative hybrids had larger stomata on both sides as well as on the abaxial side. DNA analysis of seven representative hybrid trees (H3, H7, H8, H24, H57, H64 and H70) in the orchard was studied using ISSR3, ISSR8, ISSR15 and ISSR16 markers. Six (H3, H7, H8, H24, H57, H64) contained the DNA fragments of both parental species and confirmed as hybrids. H70 showed marker allele characteristics of E. alba but the number and size of stomata were typical of the hybrids, since it was originated from an E. urophylla mother tree, it should be considered a hybrid.