Comparative Research Of Life History Between Acrostichum Aureum And Isoetes Sinensis

Both Acrostichum aureum and Isoetes sinensis are aquicolous pteridophyte. A. aureum is a kind of fern which grows in salt water or half salt water of costal tide zone. I. sinensis is a kind of fern-allies, and which is an endemic species of middle and downside of Long River. It can't adept to the enviroment suitably, and in danger situation. Now it has been defined as first grade protected plant. The present paper choose these two species as materials in order to compare their features of morphology, development and physiology in life history, and find out why these two species are all aquicolous pteridophyte, while their systematic location is so far away from each other. Basal data are also provided for knowing systematic significance and physiological significance of aquicolous pteridophyte.The spores of A. aureum and I. sinensis were cultivated artificially. Life history of the two species were observed detailedly by microscope and using the method of serial sections. Including gametophyte development, embryo and young sporophyte formation, sporophyte development and so on.The spore of A. aureum is trilete, tetrahedral. Spore germination is of Vittaria-type. The gametophyte is abnormal cordiform, and the two wings of which are different in size. Sexual organs are general type of homosporous leptosporangiate ferns. The sperm is coiled, which would be actively in 15 minutes after relesed from antheridium. The macrospore of I. sinensis is trilete, tetrahedral. Gametophyte development is in cell wall. First, the interior of macrospore is even material, then dissociative nucleus formed, followed cell structure formed. And the embedding archegonia is produced by this cell. The microspore is monolete, in which sperm cells formed.The embryogenesis of A. aureum is prone. The first division of the zygote were by the first divided plane which was parallel to X plane, and produced two equal hemispheric cells. The two daughter cells were divided parallel to Z plane, and formed four cells. The four cells divided parallel to Y plane and produced eight-cell embryo. The following divisions produced a spherical shape embryo. In this stage, the first leaf original cell was differentiated in the outer-anterior region, while the first root original cell in the outer-posterior region; the inner-posterior region developed into the foot primordium, while the shoot primordium were differentiated from the inner-anterior region. The primordiums of the first leaf and of the first root were developed into the first leaf and the first root. When the first leaf was formed, the shoot primordium that developed from the inner-anterior region and being at the basal part of the petiole resumed activity and pierced out of the embryo surface, then differentiated out of the second leaf primordium, from which grew up to the second leaf. The embryogenesis of I. sinensis is fast. When the egg was fertilized, it quicklly developed into multicellular spherical shape embryo, then part of spherical shape embryo which near the neck of archegonia grew rapidly, circumrotate about 45°during the process of embryo development, and finally protruded tissue of female gametophyte formed leaf. At the base of spherical shape embryo, the root formed and its growth orientation vertical to the growth orientation of leaf. The angle between root and archegonia is about 45°.The leaf shape of A.aureum is fan-shaped. Three main veins formed dichotomously branched from the basal part of the petiole, then the main veins form dichotomously forked branches, the terminals of branches link together and form reticulation. The stomatal apparatus type are Polocytic type, Diacytic type and Anisocytic type. The I.sinensis can only produce one acicular leaf in one female gametophyte, and the leaf with sheath. When sporophyte mature the leaves cluster in the corm. The sporangium formed at the basal part of leaf innerlly. There is developed ligule between leaf and sporangium. Under the corm are dichotomously branched adventitious roots formed. The adventitious roots and leaves of Isoetes are all solid at first, then formed aerenchyma. The sporangium is also solid at first, then forms cavum and with septum, the spores formed in the cavum.Under white light and yellow light the germination rate of spores of A. aureum is higher, and under the red light and blue light that is lower, but the spores would not germinate in the dark. The white light is best for gamtophyte development of A. aureum, following by yellow light, red light and blue light, and 25℃is best for gametophyte development. The germination rate is good under pH which between 5.7 and 8.7. For I.sinensis,20℃is the best temperature for female gametophyte germination.The characteristics of the two aquicolous pteridophyte are compared. The present paper provides basal data for gametophyte development and embryogenesis of pteridophyte, as well as transplant and nursery. Systematic significance in morphology, ecology and physiology of aquicolous pteridophyte at different systematic location is discussed.