Morpho-anatomical, palynological studies on Astragalus microcephalus; Anatolian tragacanth

Abstract

Astragalus microcephalus Willd. (Fabaceae) is a member of the section Rhacophorus Bunge and is an element of the Irano-Turanian phytogeographic region. It grows mainly in the steppes of central Anatolia. Extraction of tragacanth and selenium is a valuable tool in pharmacy and is also important economically and ecologically. In this study, morphological, anatomical, pollen characteristics and seed surface properties of A. microcephalus were investigated in detail. The plant consists of thorny bushes that make up a pillow. Morphological characters such as the shape of paripinnate leaves, stipules and bracts, flowers whitish-yellow and purple colored in margins, the flower number in the inflorescence, the stenonychioid type of standard and reniform type of seed can be helpful to distinguish species of Astragalus. There is secondary growth in stem anatomy. The stem of this species has got tragacanth canals in pith. Sclerenchyma tissue is well developed in the petiole. A. microcephalus has equifasial leaves. The vascular bundles are surrounded by a bundle sheath. The pollen grains of A. microcephalus are tricolpate and prolate-spheroidal. The exine sculpturing is microreticulate with perforate while the seed surface is rugulate. Scanning electron microscopy (SEM) is used to determine pollen and seed morphology.