Plant speciation on tropical mountains: Leptospermum (Myrtaceae) on Mount Kinabalu, Borneo

The genus Leptospermum (Mytaceae) is represented on Mount Kinabalu, Borneo, by L.flavescens (widespread on Malesian mountains and uplands) and L.recurvum (endemic to Mount Kinabalu). Analysis of the general morphology, leaf characters, leaf anatomy and flavonoid content of field collection, of both taxa at 1970–4000 m indicated that L.recuruum is a distinct species, most probably derived from L.flavescenS. L.recurvum individuals display a striking variation in leaf pubescence. Seedlings of. These plants grown under uniform conditions were not genetically variable (as seen in the uniformity of peroxidase and acid phosphatase isozymes).Variation that did occur was not correlated with altitude or any other identifiable ecological factors. The sporadic distribution of individuals producing non-viable seeds, probably an expression of genetic load, is another indication of a lack of genetic diversity. L.recurvum may have evolved from a population of L.flaurscens on Mount Kinabalu, most probably during the Pleistocene.