Diagnostic signs of morphological and anatomical structure of Medicago falcata L. raw materials

Topiciality. Flora of Azerbaijan has a diverse vegetation cover and is rich in choice. However, today these sources of raw materials are not fully used to meet the needs of medicine and national economy. We conducted a resource reconnaissance survey of species of the genus Medicago in Azerbaijan and identified regions of mass growth. New natural habitats are located in different environmental conditions and it is possible to change the diagnostic features of the morphological and anatomical structure of plant materials, as well as the chemical composition. The combination of additional morphological and anatomical features allows a more accurate determination of the authenticity of the raw material. Aim. To study the diagnostic signs of morphological and anatomical structure of Medicago falcata L. raw materials from the flora of Azerbaijan. Materials and methods. Plant samples were fixed in a solution made in 0.1 M phosphate buffer (pH = 7.4), containing 2.5 % glutar-aldehyde, 2 % paraformal-aldehyde, 4 % sucrose, and 0.1 % picric acid. The fixed materials have been submitted to the Electron Microscopy Laboratory of the Azerbaijan Medical University for study by electron microscopy. Samples have been postfixed in 1 %-osmium tetraoxide solution prepared in phosphate buffer (pH 7.4) within two hours after being left in the same fixer for one day. Araldite-Epon blocks made from materials using general methods adopted in electron microscopy. The semi-thin (1-2 μm) sections from the blocks taken on a EM UC7 (Leica, Germany) ultramicrotome, stained with methylene blue, azure II, and basic fuchsin were observed under microscope Primo Star (Zeiss, Germany) and images of required parts were shot with EOS D650 (Canon, Chine) digital camera. Results and discussion. Multicellular trichome covered on both leaf sides. Adaxial epidermis a sheet plate have sinuous cells, and abaxial epidermis have differed slightly sinuous cells with clear-shaped walls. In leaflet anatomy of plant vascular bundles are of the collateral type. Stomatas are located from both sides of a leaf. Stomata belong to anisocytic structure. The epidermis of the stem consists of elongated thick-walled cells with anisocytic stomata. The calyx is densely covered by trichomes. The outer epidermis of cross-section of the keel petals cells is the wing horns cells form. And inner epidermis consists of oval cells. Mesophyll cells inside the leaf consist of loose spongy cells on the underside with several conducting bundles (dorsoventral). Conclusions. Morphological and anatomical studying of raw material Medicago falcata L. has shown, that there are prominent features of a structure:four large conductive bundles are located on the cross section of the stem at the corners of the ribs on two sides. Between angular conductive bundles, there are three conductive bundles, and the other two sides are located along one conductive bundle. Therefore, M. Falcata L. differs from M. Sativa L. The epidermis of the stem consists of elongated thickened-walls cells with anisocytic stomata. The indicated diagnostic morphological and anatomical characters could be used in the compilation of a monograph and in identifying plant materials on the raw material of Medicago falcata L.

Ключевые слова: анатомия; морфология; растительное сырьё; Medicago falcata L.; диагностические признаки INTRODUCTION Flora of Azerbaijan has a diverse vegetation cover and is rich in choice. However, these sources of raw materials today are not fully used to meet the needs of medicine and national economy. The main reason for this is the insufficient study of the chemical composition and biological activity of plants and the lack of information about the raw material base [1].
The genus Medicago a perennial herbaceous plant from the legume family (Leguminosae) consists of more than 100 species common in Europe, Africa, Asia. In Azerbaijan, the genus Medicago L. is represented by 21 species [2].

ISSN 2311-715X (Print) ISSN 2519-8750 (Online)
Species of the genus Medicago, growing in various regions of the world, have been studied in chemical composition and biological activity [3,4,5].
For the first time, flavonoids laricitrin, genistein, and biochanin A were isolated from the aerial part of M. littoralis [6]. The quantitative content of isoflavonoids formononetin, genistein and irilone in the species M. orbicularis, M. doliata and M. arabica was significantly higher than in raw material soybean and red clover [7]. Triterpene saponins were isolated from the roots of M. sativa and M. truncatula and identified as medicagic acid, hederagenin, soyasapogenol B and E [8]. M. sativa extract has hepatoprotective and antioxidant properties under stress [10]. Microscopic features and physicochemical parameters for standardizing plant materials of M. sativa were established [11].
We conducted a resource reconnaissance survey of species of the genus Medicago in Azerbaijan and identified regions of mass growth. We conducted a preliminary phytochemical analysis of the aerial mass of M. falcata harvested during the flowering phase and established the presence of flavonoids, coumarins, triterpene saponins and other, less important substances in it.
New natural habitats are located in different environmental conditions and it is possible to change the diagnostic features of the morphological and anatomical structure of plant materials, as well as the chemical composition.
In some monographs on raw materials, a limited number of characters are given, and sometimes features characteristic of a family or genus are indicated. The plant material "herb" is harvested in the flowering phase and it is desirable to give signs regarding pollen, seeds, corolla. The combination of additional morphological and anatomical features allows a more accurate determination of the authenticity of the raw material.
The aim is to study of diagnostic signs of the morphological and anatomical structure of Medicago falcata L. from the flora of Azerbaijan.

MATERIALS AND METHODS
The samples for research were collected during their flowering time in May 2019, in the Shamakhi region (40.6427°N, 48.6267°E) of the Republic of Azerbaijan. Plant samples were fixed in a solution made in 0.1 M phosphate buffer (pH = 7.4), containing 2.5 % glutar-aldehyde, 2 % paraformal-aldehyde, 4 % sucrose, and 0.1 % picric acid. The fixed materials were submitted to the Electron Microscopy Laboratory of the Azerbaijan Medical University for study by electron microscopy. Samples were postfixed in 1 %-osmium tetraoxide solution prepared in phosphate buffer (pH 7.4) within two hours after being left in the same fixer for one day. Araldite-Epon blocks were made from materials using general methods adop-ted in electron microscopy [12]. The semi-thin (1-2 µm) sections from the blocks taken on a EM UC7 (Leica, Germany) ultramicrotome, stained with methylene blue, azure II, and basic fuchsin were observed under microscope Primo Star (Zeiss, Germany) and images of required parts were shot with EOS D650 (Canon, Chine) digital camera [13].

RESULTS AND DISCUSSION
Morphological characteristics M. falcata L. is perennial plant belonging to the genus Medicago of the family Leguminoase. The plant is erect or stems prostrate to upright, arising from the crown, up to 40-60 (100) cm, roots well-branched, rarely taproot or rhizomatous. Leaves and stems covered sparsely to densely with hairs. Leaves are oblong or obovate with serrations, compound, the base is narrowed, the upper and the lower surface is hairy. The length of leaflet is 8-20 mm. The apex of the leaflet is acute. Stipules entire or toothed at their base. The stem, leaf rachis and peduncle are covered with hairs also (Fig. 1). Petioles are 0.3-1.5 mm. Stipules are 0.4-0.9 mm, lanceolate. Inflorescence is 1.1-2.5 cm, dense raceme. It has raceme of small yellow flowers followed by fruits containing 10-18 seeds. Seeds are flat, yellow brown, 10-12 mm long, semi-spiral, glabrous or slightly hairy.

Anatomical characteristics Leaflet anatomy
The transverse sections of leaflets show that the upper and lower epidermis consist of uniseriate, oval or isodiametric cells with adaxial and abaxial cuticles. The lower epidermal cells are similar to those on the adaxial surface there are some slightly sinuous cells with clear-shaped walls. Both leaf surfaces have stomata (Fig. 2). Epidermal cells are tightly linked to each other and stoma belongs to the anisocytic structure. Mesophilic -chlorenchyma tissue consists of 1-2 layered the palisade parenchyma cells and 4-5 layered spongy parenchyma cells (Fig. 3). The mesophyll tissue separated into a distinct palisade zone in the adaxial portion of the leaf, and spongy mesophyll in the abaxial portion. The spongy parenchyma cells are present isodiametric spongy parenchyma cells with large intercellular spaces. There are more trichomes present both surfaces, especially along the veins.

Steam anatomy
The stem is about square in cross section. The stem epidermis is composed of large elongated thick-walled cells with stomata of the anisocytic type. Vascular bundles are located in the angles of the axis. Vascular bundles in M. Falcata L. are collateral. The epidermis is underlain by chlorenchyma and collenchyma and the innermost layer of the cortex is the starch sheath. Collenchyma tissue is composed of cells withthick cell walls. Pith is composed of large, compactly arranged parenchyma cells. Phloem and xylem are well developed. Phloem parenchyma and companion cells are present in the phloem. The center of the is occupied by the pith.The pith region of the stem consists of parenchymtic cells and some of them include dark secretions (Fig. 4).

Petal anatomy
The papilionaceous corolla is consists of five petals: a large standard or banner, two lateral wing petals and two fused petals that form the keel. The keel petals is composed of outer epidermis and inner epidermis. Outer epidermis changes their shape to wing horns cells. The transverse section of the keel petals consists of scattered vascular bundles (Fig. 5).
Morphological and anatomic studying of raw material Medicago falcata L. has shown, that there are prominent features of a structure. Some of the microscopic features for standardizing plant materials of M. Sativa L. were established [11]. This is the first report on the examined characteristics of the M. Falcata L. in flora Azerbaijan. Transverse sections of stems of the plant were studied for microscopic characters. Multicellular trichome covered on both leaf sides. Adaxial epidermis a sheet plate have sinuous cells, and abaxial epidermis have differed slightly sinuous cells with clear-shaped walls. The trans-verse sections of stem of M. Falcata L. are made up three main tissues from outside to inside and their names are epidermis, vascular bundles and pith region. Transverse section in the main stem some Medicago sativa L. cultivars were carried out; stained and seventeen anatomical characters were examined by light microscope [14]. In leaflet anatomy of plant vascular bundles are of the collateral type. Stomatas are located from both sides of a leaf and are surrounded by three or four unequal cells. Stomata belong to anisocytic structure. The epidermis of the stem consists of elongated thick-walled cells with anisocytic stomata. The calyx is densely covered by trichomes. The outer epidermis of cross-section of the keel petals cells is the wing horns cells form. And inner epidermis consists of oval cells.
Morphological and anatomical characteristics might be useful in the definition of the species investigated. These characteristics will be more valuable if other species of Medicago are also investigated.

CONCLUSIONS
Morphological and anatomical studying of raw material Medicago falcata L. has shown, that there are pro minent features of a structure: four large conductive bund les are located on the cross section of the stem at the corners of the ribs on two sides. Between angular conductive bundles, there are three conductive bundles, and the other two sides are located along one conductive bundle. Therefore, M. Falcata L. differs from M. Sativa L. The epidermis of the stem consists of elongated thickened-walls cells with anisocytic stomata.
The indicated diagnostic morphological and anatomical characters could be used in the compilation of a monograph and in identifying plant materials on the raw material of Medicago falcata L.
Conflicts of interest: authors have no conflict of interest to declare.