Anatomical Studies on Species of Subfamily Stachyoideae (Lamiaceae): Naturally Growing in the Kingdom of Saudi Arabia

This study deals with the epidermal and internal anatomy of the stems, leaves, floral parts and pollen grains of the following 14 species of the subfamily Stachyoideae. Epidermal characters indicate that cells are polygonal isodiametric with sinuous or straight anticlinal wall; cells arranged in a parallel rows at the veins of the leaves, stems and floral parts (calyx and corolla) and stem angles. Stomata present on both epidermises of intercostal regions, leaves are amphistomatic (stomata on the lower and upper surfaces) and absent at the veins of the leaves and floral parts, stomata commonly diacytic or anomocytic, occasionally anisocytic, occur more frequently on the lower surface, number of stomata per mm2 of leaf or flowers on lower surface are higher than those of the upper surface. Number of stomata range from 600 ? 50/mm2. Trichomes are numerous on both plant vegetative and floral parts. Trichomes divided to glandular and nonglandular and occur intermixed. The internal structure of the species under investigation indicate a unique similarity in their anatomical characters in spite of belonging to different genera.