Leaf anatomy of the subtribe Hyptidinae (Labiatae)

The leaf anatomy of the subtribe Hyptidinae (Labiatae), which consists of four small genera and the large genus Hyptis, is described. The leaves may be dorsiventral or isobilateral. Variable characters of the lamina include: frequency and forms of trichomes, cuticular markings, presence of adaxial stomata, thickness of leaf, thickness of adaxial epidermis, presence of a hypodermis, occurrence of sclerified tissues (especially sclerified bundle sheath extensions, phloem and xylem fibres), mesophyll structure and venation pattern. Petiole vasculature varies from simple to complex, sometimes with medullary traces present. Most of the variable characters are related to xeromorphy and are tax-onomically useful within the framework of the present classification.