Achene morphology of the genus Cota J.Gay (Asteraceae) from Turkey and its taxonomic significance

Abstract

Twenty-two taxa of the genus Cota J.Gay (Asteraceae) from Turkey were examined with a stereomicroscope and scanning electron microscope (SEM) in order to describe their achene macro- and micromorphologies and to evaluate the diagnostic value of these features. The achenes are obpyramidal, obconical, and oblong. Achene width ranges from 0.26 to 1.68 mm and achene length from 1.13 to 3.46 mm. They show variation in color: brown, dark brown, grayish-brown, reddish-brown, purplish-brown, black, and purplish. All investigated species have slime cells, but prismatic cells on epicarpic cells are found only in two species. Four types of ornamentations were recognized via SEM on achene surface characteristics: reticulate-striate-ruminate, reticulate-striate, reticulate-ruminate, and reticulate-rugose. Achene size, surface ornamentation, and color are of significant importance in taxonomy of the genus for distinguishing taxa from each other.