Nutlet morphology and its taxonomic implication in some taxa of Lamiaceae in Egypt

Abstract

Nutlet morphology of 28 taxa belonging to 15 genera of Lamiaceae were examined using light and scanning electron microscopy. The taxa included representatives of the three subfamilies Ajugoideae, Lamioideae and Nepetoideae which all collected especially from Sinai, Egypt. Morphological characters, including nutlet shape, color, size; hilum (shape, length x width and position); epidermal cell shape; anticlinal walls (level, undulation, thickness and secondary sculpture); outer periclinal cell walls (level and secondary sculpture) are presented. The reticulate type was the most common among the studied taxa. Four types of basic anticlinal cell wall boundaries were recognized and many different shapes of the outer periclinal cell wall were described. Nutlet ornamentation, shape, size, colour and particularly hilum characters proved to be good taxonomic characters for the Egyptian Lamiaceae taxa. A key for the identification of the investigated taxa based on nutlet characters is provided.