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.
|Published (Last):||23 October 2013|
|PDF File Size:||6.62 Mb|
|ePub File Size:||20.74 Mb|
|Price:||Free* [*Free Regsitration Required]|
The structure of the wall of sporocarp and the gelatinous ring is the same as in transverse section.
It is the outermost limiting layer of single celled thick parenchymatous cells. It has a single layered jacket followed by two layers of tapetal cells. In this article we will discuss about: Both antherozoid and egg fuse to from a diploid oospore 2x. Mesophyll tissue is differentiated into palisade and spongy parenchyma and generally associated with vertical airspaces.
At the time of their separation from the gelatinous ring off ventral ends of the sori are torn off and sporangia of with spores escape from ljfe ventral ends of the sori megaspore mother cells However, the indusia and the jackets of sporangia become gelatinized and the spores are liberated. The protoxylem may be well defined exarch M. The megaspore is ellipsoidal and possesses a small projection at the anterior end.
Division of a leaf-blade into four leaflets results from cyc,e dichotomies arising in close succession to each other. Some of the tannin cells may be found in this innermost region.
Upon rupturing, the sorophorea gelatinous bubble linking individual sori in a chain, exposes the megasporangia and microsporangia to the surrounding environment. First of all the starch grains of the microspore migrate to the periphery of the cytoplasm and the nucleus generally shifts to the broad side of the microspore. Top 17 Problems on Statistics With Solution.
Marsilea: Habit, Structure and Reproduction
Each sorus has a receptacle which has a central terminal megasporangium and two lateral microsporangia, one on either side. In majority of the marslea of Marsilea near the point of attachment of the stalk or peduncle at the base, there are usually one and cylce more protuberances in the median plane.
The shape of pinna varies from obovate to obcuneate and margin also varies from entire to crenate or crenate to lobed. This means that these sporocarps are the branches of the leaf.
The rhizome is slender, branched and possesses nodes and internodes. Each sorus is surrounded by a thin, membranous two layered true indusium. This way, the active and living antherozoids may be easily differentiated from the dead antherozoids which have become non-motile and inactive.
Simultaneously, the central cell divides into two cells, a small primary canal cell and a large primary venter cell. Each megasporangium contains a large single megaspore while the microsporangium contains many small rounded microspores.
It can be differentiated into two parts: The 3 lateral cells and a basal cell by further horizontal and vertical divisions form a jacket round the archegonium. Anatomically, the wall is differentiated into three layers. Stele is amphiphloicsiphonostele liff. The latter divides to form an upper ventral canal cell and a basal egg.
The leaves possess circinate vernation typical of most Filicales ferns.
The mucilage ring is present in the form of two masses, one in the dorsal and the other in the ventral sides. The primary sporogenous cell divides to form a mass of either 8 or 16 spore mother cells. However, the vascular supply to the peduncle of the sporocarp and the vascular supply to the interior of the sporocarp prove that the sporocarp is a modification of leaf-segment pinna rather than that of an entire leaf.
The tissues slowly swell up by absorbing water in natural conditions.
The epidermis is composed of single-layered parenchymatous cells, outer walls of which are thickly cuticularised. The inner cortex is delimited by single layered thick endodermis. The stem is long, slender and freely-branched rhizome of indefinite growth that grows on or just below cycl soil surface.
Each primary androgonial cell divides to form 16 androcytes Sperm mother cells and finally metamorphosises into antherozoids. Two rows of soral mother cells appears on ventral side cydle the young sporocarp.
Useful Notes on the Life History of Marsilea ( Words)
Located on petiole branches of the sporophyte, these nut-like structures contain microsporangia and megasporangia attached to sori chains. This region may be one to several celled in thickness. The gelatinous ring appears in the form of dorsal and ventral mass as in H.