Seed morphology and testa ultrastructure in Alliumstipitatum complex (Amaryllidaceae; Allioideae) and their systematic significance

Abstract

Characteristic features of seed and testa cells in 13 species of Allium, representing its five recognized sections, Compactoprason, Megaloprason, Procerallium, Decipientia and Pseudoprason were studied using both stereomicroscope and scanning electron microscope. The identified characters, such as seed shape, alignment and shape of testa cells, features of outer cell walls, verruca type, density of verrucae and granules, seed size as well as cell wall undulations were evaluated statistically. The our findings indicated the significance level of P ? 0.01 for examined characters using the Kruskal-Wallis and ANOVA analyses.Two principal components of factor analysis revealed the following traits to be most important in distinguishing taxa at various taxonomic ranks within the complex (sections, subsections and species), based on 50.94% of total variance and a correlation coefficient of 0.93: shape and sculpturing of periclinal walls, undulation details of anticlinal walls, verruca type, testa cell alignment, and size of seed and testa cells. The general pattern of testa shared by all taxa of studied complex included convex periclinal walls with verrucate surface and undulated anticlinal walls from S- to U-like, but some taxa differed from each other in the details of testa sculpturing. Exceptionally, the monotypic section, Decipientia revealed adifferent pattern, showing smooth seed surface composed of polygonal testa cells with tightarrangement, flat periclinal surfacebearingsulcate verrucae, and straight anticlinal walls.