Comparative Studies On Morphology And Anatomy Of Medicago Falcata From Different Geographical Origins

Medicago falcata L. is a perennial forage in leguminosae, with many excellent characteristics such as good palatability, nutrient-rich, cold and drought resistance, poor soil-resistant, and pests resisting. It is not only the important forage resources, but also is the important source of resistance genes in alfalfa breeding. The results that were obtained by comparative studies based on morphology, anatomy and palynology of M. falcata from different geographical origins showed as follows:1. Each organ of M. falcata from different geographical origins has been shown the rich genetic diversity. The variation within population was greater than that between populations and the variation of the vegetative organs was greater than that of reproductive organs. There were four root system types, three stem colors, seven leaf shapes, five hair coat types on leaf surface, four flower colors and thirteen pod types.2. The root, stem and leaf of M. falcata have contained fully developed parenchyma and xylem vessel. The stem was covered by the waxiness, with many bundles. The mesophyll tissue of bifacial leaf has obviously differentiated between the fully developed palisade tissue and spongy tissue. There were many stomata and epidermal trichomes on leaf surface. There were many stomata in per area of M. falcata balde, and then there were larger stomatic chambers under the stomata. The stomatal density of upper epidermis was significantly denser than it of lower epidermis. The majority of trichomes were growing on lower epidermis. There was no difference in the anatomical structure of root, stem and leaf among the different M. falcata materials. However, it showed significant difference in the numerical characters of anatomy such as the number of the vascular bundle, stomatal density, the distribution and density of trichomes, thickness of blade and mesophyll tissue and the diameter of the vascular bundle.3. The pollen shapes of M. falcata was prolate and oval in equator view, subrotundity or 3-labed-rounded in polar view. The polar axis of the pollen grains is 42.1～48.0μm, and the equatorial axis 24.4～26.9μm, which belong to medium type. And 3-colposate with pore film,rectangle or subsquare inner foveola,the style of M. falcata pollen is N3P4C5. There are significant differences in sizes and the exine ornamentation among materials of M. falcata pollen grains.4. There were significant differences in characters of morphology, anatomy and palynology, between diploid and tetraploid of M. falcata. Diploid plants had orange coloured flowers, dwarf and strong creeping plants, many vascular bundles in stem, narrow and short leaves, linear leaves, linear pod, dense hairs on both sides of blade, larger stomatal density on both epidermis of blade, thiner palisade tissue, shorter diameter of vascular bundle, lower tightness of palisade tissue, smaller pollen and deeper surface ornamentation of pollen.