Morpho-anatomical and palynological properties of endemic Astragalus tmoleus var. bounacanthus (Fabaceae)

Abstract

Astragalus tmoleus Boiss. var. bounacanthus (Boiss.) Chamberlain is a member of the Pterophorus Bunge section of the Fabaceae family and consists of the spiny cushion-forming shrub. In this study, morphological, anatomical and pollen properties of the plant, an endemic species for Turkey, have been investigated in detail. Morphological characters such as the shape of paripinnate leaves, stipules and bracts, the flower number in the inflorescence, the stenonychioid type of standard and the reniform type of seed can be helpful to distinguish A. tmoleus var. bounacanthus. The stem, leaf and rachis characteristics of the plant were examined in anatomical studies. There is a secondary growth in stem anatomy. The number of vascular bundles is 15-18 in a circle. The shape of the transversal section of the rachis is polygonal or almost orbicular. The sclerenchyma tissue is located on the vascular bundles in the rachis. A. tmoleus var. bounacanthus has equifasial leaves. The stomata type is anomocytic and occurs on both leaflet epidermises. The pollen grains of A. tmoleus var. bounacanthus have tricolpate aperture and they are subprolate-shaped. While the pollen exine sculpturing is microreticulate, the seed surface sculpturing is a prominent undulate-ridged pattern formed by irregular cells. Scanning electron microscopy (SEM) is used to determine pollen and seed morphology.