Geographic variation in seedling morphology of Casuarina equisetifolia subsp. equisetifolia (Casuarinaceae)

Abstract

Seeds collected from 28 natural provenances and introduced populations of Casuarina equisetifolia subsp. equisetifolia L. from Oceania, Asia and Africa were used to study geographic variation in growth and morphology of nursery-grown seedlings. Ten characteristics related to growth and branching habit were measured for each seedling and the resultant data subjected to univariate and multivariate analyses. In general, seedlings from Oceania grew more slowly, were more densely branched with fine and upright branching, and had fewer teeth per whorl than those from other areas. Cluster analysis effectively separated Oceania from Asian natural provenances, and revealed the probable original sources of introductions to different parts of Asia and Africa. Further investigation into the pattern of variation through molecular characterisation of genetic material from all major regions of distribution is warranted in order to better understand the genetic relationships and enhance more efficient utilisation of this important casuarina species.