Taxonomic significance of seed macro-micromorphology of Turkish Alcea L. (Malvaceae) through light microscopy and scanning electron microscopy.

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Seed morphological properties of 19 taxa belonging to the genus Alcea L. (Malvaceae) distributed in Turkey were investigated using a light microscope and scanning electron microscope to identify their characters and to evaluate their diagnostic value. The seeds are reniform with a rounded apex and base, reniform in shape, and light to dark brown, grayish-brown, or blackish-brown in color. The seed length ranges from 2.22 to 6.5 mm and seed width from 1.72 to 6.5 mm. The indumentum at the ventral and dorsal regions of the seed differs in density. Three types of seed coat ornamentations were observed: reticulate, reticulate-rugulate, and reticulate-ruminate on the dorsal and lateral faces. Principal component analysis was used to evaluate the important seed morphological characteristics among the taxa studied, with four components accounting for 90.761% of the total variance. Numerical analysis revealed that seed size, color, seed surface patterns on dorsal and lateral sides, indumentum at dorsal and ventral regions, and periclinal surface sculpture of epidermal cells are particularly the most useful variables for discriminating the Alcea taxa. The findings also showed a partial relationship among the Alcea taxa clusters, based on seed morphology and the systematics of these taxa, based on general macromorphology. Taxonomic key using the seed features is provided to identify the species studied. The current work will contribute to the knowledge about the family Malvaceae, and microscopic macro-micromorphological analysis can be used for identification by the taxonomists for further studies on this family. RESEARCH HIGHLIGHTS: Seed color, indumentum and surface sculpturing have systematic value for separating the taxa. Seed morphology of the Alcea taxa was studied via light microscope and scanning electron microscope. Numerical analysis provided the contribution of seed characters to taxa relationships.