Taxonomic Importance of Leaf Domatia of the Five Species of the Genus Cornus in Korea

Three types of leaf domatia; Pocket (P), Tufts (T) and Tufts-Pocket (TP) were observed in the five species of Cornus namely; Cornus kousa, C. controversa, C. officinalis, C. walteri and C. alba. In C. walteri no tufts were observed, the domatia was just a well developed pocket one. In C. officinalis and C. kousa, tufts domatia of brownish color were observed but C. officinalis developed denser tufts than those observed in C. kousa. Unlike in C. kousa where the domatia covered about only 1/2 of the axil, in the C. officinalis tufts covered almost 3/4 of the axil. In both species the tufts domatia were located in the inner side of the leaf axil. In C. controversa and C. alba whitish colored tufts were observed covering Pockets and hence the Tuft Pocket domatia. In C. controversa the tufts were more than in C. alba but in both species the tufts were short and were located in the inner sides of the axil. Thus, based on these physiological features it was concluded that C. officinalis and C. kousa are sister species likewise C. controversa and C. alba while C. walteri belong to another lineage. The advancement of domatia (absence of tufts) in C. walteri suggests that they are the most advanced while C. officinalis and C. kousa the most primitive due to their possession of highly developed tufts and C. controversa and C. alba the intermediates.