A Comparative Anatomical Study of Stem and Leaves of the Genus Trigonella L. Species (Fabaceae) in North of Iraq

Anatomical evaluation of 11 Trigonella L. species was carried out after preserving the sample parts in FAA solution, and the sample tissues were sectioned by the paraffin method. The results revealed significant anatomical feature differences among the stem and leaf parts in the studied species. Although, prismatic crystals and tannins were present in all the species, the shape of the stem, petiole, midrib, margin outlines, and vascular bundles arrangements were anatomically varied, as well as the presence of hairs, that were unicellular glandular or non-glandular among the species. The fiber and collenchyma tissues exist in stems, petioles, and midribs in all studied species. Stem outline shapes differed between taxa, however, T. caelesyriaca differed from the other species in the vascular bundles which were loosely arranged, and in T. strangulate were three large vascular bundles interruptedly arranged in a ring. In spite of the variations among the petiole outlines no accessory vascular bundles were observed in T. aurantiaca. The leaflet midribs showed different outlines, the accessory vascular bundles were observed only in T. monantha var. monantha and T. aurantiaca. As for the differences observed in the margins of the leaflets were rounded upwards in most taxa, nevertheless, the margin is rounded straight in T. spicata, T. stellate, and T. foenum-graecum; rounded downward in T. monspeliaca, T. caelesyriaca, and T. aurantiaca; where pointed upwards in T. monantha var. monantha and T. filipes.