Leaf Anatomy of Vatica L. (Dipterocarpaceae) in Thailand

Abstract

The leaf anatomical characters of all species of the genus Vatica L. in Thailand were investigated by leaf epidermal clearing, transverse sectioning of the lamina and petiole, and examination by scanning electron microscopy (SEM). The generalized anatomical characteristics in all species are as follows: 1) one-layered epidermal cells; 2) hypostomatic leaves; 3) the presence of bundle sheath extensions to both epidermises or at least on the adaxial side; 4) the presence of stellate trichomes on the petioles; 5) the presence of resin canals; and 6) druse crystals in the mesophyll, midribs and petioles. Moreover, the present investigation indicates that anatomical characters which are significant for species delimitation are 1) cuticular ornamentation; 2) the level and types of stomata; 3) the distribution and types of trichomes; 4) the occurrence of a palisade cell layer in the laminas; 5) the number of resin canals in the petioles; 6) the presence/absence of sclereid cells in the midribs; 7) the presence/absence of fiber cells in the mesophyll and leaf margins; 8) the crystal types; and 9) the starch grains in ground tissue. In addition, the genus can be divided into two distinct groups based on the petiole anatomy by having the different numbers of resin canals, which supports the grouping based on the morphological data.