Taxonomic implications of leaf morphology and epidermal anatomy for 14 species of Gagea (Liliaceae) from Xinjiang, China.

Abstract

Background: Leaf morphology and epidermal characters are important for phylogenetic and taxonomic studies of many plants, but there is currently insufficient data to use them to help distinguish species of Gagea, which is a taxonomically difficult genus mainly due to polyploidy and hybridization. Therefore, leaf morphology and epidermal characters of Gagea were studied to assess the characters that can be used to elucidate the taxonomy and systematics of 14 species of Gagea collected in Xinjiang, China. Using light microscopy (LM), six qualitative and three quantitative leaf epidermal anatomical characters were examined for both the adaxial and abaxial surfaces. Hierarchical cluster analysis (HCA) was employed to reveal the similarities based on leaf morphology and epidermal characters of the investigated species.

Results: Basal leaf of these species can be terete or flat, and it is triangle, flat, or circular in transverse section. Anticlinal wall patterns of the leaf epidermal cells were straight and sinuous, and only three species had epidermal hairs. Shape of long cells varies, ranging from quadrangular to irregular. HCA revealed that the 14 species could be divided into two groups. Group A was arranged into three subgroups (A1, A2 and A3), based on the Euclidean distance of 6.96. Subgroup A1 consisted of three species with indumentum; subgroup A2 had four species with sinuous type anticlinal walls; and subgroup A3 comprised of two species with a fistulose basal leaf. Group B included five species with short cells.

Conclusions: Leaf morphology and epidermal characters did not differ significantly among populations of the same species in Gagea, whereas they differ significantly among species. Thus, leaf morphology and epidermal characters provide diagnostic information for differentiating G. nigra and G. filiformis; G. altaica, G. jensii and G. alberti, which are morphologically similar species.