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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It is the outermost layer of single cell thickness. There are three views which can be grouped under the following categories: This means that these sporocarps are the branches of the leaf. When marsilsa plants grow on mud or marshy places the leaves have got shorter and the petioles erect and stouter which spread the leaves in the air. It takes place from a superficial cell situated laterally on the receptacle. The development of megasporangium is exactly in the same way as that of ot except that out of the total number of megaspores formed, all degenerate leaving except one which behaves as a functional megaspore x.
The phloem is bounded externally by a single layer of pericycle.
The microspore for the first time divides by an asymmetrical wall forming two unequal cells—a small lenticular or prothallial cell and a large apical cell. This cell behaves as a two sided apical leaf cell and cuts off segments on either side. The apical cell cuts off basal cell but this is very much doubted because of the lack of evidence in support of it. Hypodermis consists of two layers of radially elongated palisade like cells. A single-layered pericycle is present just inside the endodermis.
Marsilea: Habit, Structure and Reproduction
The og sporogenous cell divides to form microspores mother cells Fig. The male and female nuclei fuse to form a diploid cyclee called oospore or zygote. In this article we will discuss about: Young leaves show circinate vernation like ferns Fig.
The structure of the wall of sporocarp and the gelatinous ring is the same as in transverse section. The spores within the sporocarp may remain viable 20 to 30 years and sometimes upto 50 years. There are two kinds of spores found in micro and megasporangia, known as microspores and megaspores. These are called soral canals Fig. In most cases the peduncle is unbranched and bears a single sporocarp at its apex. The species of Marsilea possess a rhizome which mrasilea on or just beneath the surface of the soil.
Fertilisation disintegration of the neck canal cell and ventral canal cell create a passage for the antherozoids to fertilise the egg. The mucilage ring cyxle present in the form of two masses, one in the dorsal and the other in the ventral sides.
This consists of a sclerotic zone. The roots of M. The sori reveal many megasporangia and only two or three microsporangia at the sides.
The inner cortex is composed of compact parenchymatous cells. The lateral bundle is also cut transversely below each sorus. They are cork-screw like in shape.
The androcytes are metamorphosed into antherozoids. Below the epidermis there are two hypodermal layers. The cortex is differentiated into outer and inner cortical regions. An Australian species M. In each soral canal the receptacle of the sorus faces the indusium, and sporangia arise on the receptacle in acropetal succession.
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This way, the continuation of different tissue in the amphiphloic siphonostele is as follows-outer endodermis, outer pericycle, outer phloem, xylem, inner phloem inner pericycle and then inner endodermis. Oospore is the initial stage of sporophytic generation. Habit of Marsilea 2. The water enters to the interior of the sporocarp. About 9 species have been reported from India. This region may be considered the middle cortex.
A single plant of M. Magsilea stele is surrounded by a single- layered endodermis. Top 17 Problems on Statistics With Solution. Anatomy of Marsilea With Diagram Pteridophyta.
It is also called aerenchyma.
After forming the tapetum the remaining archesporial cell, which acts as primary sporogenous cell divides lifr or 4 times successively giving rise to 8 or 16 spores mother cells. The male gametophyte is developed inside the microspore and produces 32 antherozoids with usually one prothallial cell.
Each of these cuts a single segment at each face before it acts as an archegonial initial. At night the pinna are folded upwardly. On the outside of the vascular bundle there is single layered endodermis. These soral mother cells form two alternating rows of canals. The plant body is distinctly kf into rhizome, leaves and roots Fig.
The free swimming antherozoids are attracted chemotactically towards the neck of a mature archegonium but only one enters the neck and reaches the egg. It has a single layered jacket followed by two layers of tapetal cells. The sporocarp bursts open only in water in valvecular manner along cucle ventral side and apex. In aquatic species the internodes are long while in sub-terrestrial species they are short.