Structural Characters of Leaf Epidermis in Hyoscyameae (Solanaceae) and Their Systematic Significance

The leaf epidermis of 24 species, representing 7 genera of the tribe Hyoscyameae and two related genera in the Solanaceae was examined through light microscopy (LM) and scanning electron microscopy (SEM). It was shown that the stomatal apparatuses of the 24 species were present in both upper and lower leaf epidermis. The stomatal apparatuses were often anomocytic, but sometimes anisocytic. The leaf epidermal cells were usually irregular, crossed, nearly oblong or irregularly polygonal in shape. The patterns of anticlinal walls were slightly straight, sinuolate, sinuous or sinuate. Under SEM observation, the inner margin of the outer stomatal rim was nearly smooth, sinuolate or sinuous, and the cuticular membrane of the leaf epidermis was often striated, sometimes striated, granular and scaly, and occasionally granular and scaly or smooth. Therefore, the types of the stomatal apparatuses in the tribe Hyoscyameae and the related genera are of some significance for determining the genera of Hyoscyamus L., Anisodus Link, Atropanthe Pascher and Atropa L. The shapes of leaf epidermal cells and the patterns of anticlinal walls vary among the 24 species examined which could be mainly divided into four types: (1) irregularly polygonal leaf epidermal cells and slightly straight or sinuolate anticlinal walls; (2) crossed or nearly oblong leaf epidermal cells and sinuous anticlinal walls; (3) irregular leaf epidermal cells and sinuous or sinuolate anticlinal walls; (4) irregular leaf epidermal cells and sinuate anticlinal walls. These variations correlate to a certain extent with the gross morphology, palynology and phytogeography in these genera. The cuticular membrane of the leaf epidermis in the genus Physochlaina G. Don was usually identically striated, granular and scaly, while in the genus of Hyoscyamus L. it was mostly only striated but granular in a few species. Therefore, the characters of the cuticular membrane of the leaf epidermis could serve as a criterion of distinguishing some genera and species in the tribe Hyoscyameae.