Here are your notes on the life history of Marsilea! Characteristic features: This order includes a single family, Marsileaceae. The family includes the living. Etiology Thiaminases occur naturally in Marsilea spp., Cheilanthes spp., Figure A. Growth habit and reproductive structures of the sporophyte polypody fern. .. that centriolar duplication connected to the cell cycle is a secondary event. Download/Embed scientific diagram | – Life cycle of a Heterosporous Pteridophyte (eg: Marsilea) from publication: Diversity of Pteridophytes in Western Ghats.
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In some species e.
About two or three hours later of the beginning of the spore germination, the nucleus divides which is soon followed by a transverse division. This way, the active and living antherozoids may be easily differentiated from the dead antherozoids which have become non-motile and inactive.
It can be differentiated into two parts: Each sporocarp possesses many sori which bear microsporangia and megasporangia. Shortly before the antherozoids are mature, the spore wall bursts and the antherozoids are liberated in the water. The sporocarp is a bivalved structure. From the dorsal vein, lateral branches are given alternatively right and left, at right angle to the dorsal vein which supplies laterally Fig.
The leaves are compound. After several divisions of the primary androgonial cells, sixteen androcytes are formed surrounded by jacket cells.
Marsilea: Habit, Structure and Reproduction
On the maturation of the archegonium the neck canal cell or cells and the venter canal cell disintegrate and the archegonial neck remains open. Its structure is similar to microsporangium except that only one oife is present per megasporangium at maturity. As only one megaspore survives it becomes quite large in size and thick walled as marsile other heterosporous pteridophytes. Each sorus appears to be formed in a cavity and is surrounded by a delicate, membranous indusium.
The cells are parenchymatous and slightly elongated.
Marsilea: Habitat, External Features and Reproduction
The sporocarp may easily be germinated by injuring it on the ventral median line and keeping it in the water. Marsilea is heterosporous i. It is the outermost surrounding layer and is only one cell in thickness. The vegetative reproduction takes place by means of specially developed structures known as tubers.
It can be split open in the dorsiventral plane into two halves valves. The endospore is surrounded by epispore and endospore.
The cilia are attached only to the posterior coils. How does it affect the heart? In microsporangium generally all young spores mature so that each microsporangium contains 32 or 64 microspores. It is lifw by phloem. The rhizome is dichotomously branched and is capable of indefinite growth in all directions and covers an area more than twenty-five metres in diameter. These lateral veins are given off alternately right and left. The rhizome is slender, branched and possesses nodes and internodes.
Xylem occurs in the form of a ring and is surrounded on either side by phloem.
The epidermis is single layered and composed of thin-walled parenchymatous cells. Anatomically, the wall is differentiated into three layers. A mature megagametophyte is surrounded by a broad, ovoid marilea zone which there in a watery funnel shaped opening directly upon the archegonium. Thus the gametophytic generation ends and the unit of sporophytic lide is formed. Subsequently the two initials develop on the lateral side of the megasporangium. The sporangial initial divides periclinally producing two cells, the inner cell and the outer cell.
The male gametophyte is developed inside the microspore and produces 32 antherozoids with usually one prothallial cell. In transverse section, marsileq root shows three distinct regions: A vertical transverse section VTS of the sporocarp shows only the sori on two sides Fig.
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The zygote is the mother cell of the next sporophytic generation. The gelatinous mucilage marsilae is more prominent in dorsal side. In megasporangium, only one megaspore survives to become a large functional megaspore, while all the microspores are functional in microsporangium.
The dorsal bundles are also seen. When grown in water, the whole body is submerged with just the leaf lamina floating on the surface of water.
It lies below the hypodermis and called aerenchyma. Next to hypodermal layers is the parenchymatous zone Fig. The gelatinous mass on the dorsal side is much more prominent. The mucilage ring is present in the form of two masses, one in the dorsal and the other in the ventral sides.