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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Oospore is the initial stage of sporophytic generation.
Stomata are present in the upper epidermis in submerged species or on both the upper and lower epidermis in terrestrial and amphibious species. The primary root grows vertically and establishes the sporeling in the soil. Some of these cells are filled with starch or tannin. Usually the attachment of the gelatinous ring breaks from the ventral side of the sporocarp and the dorsal part of the gelatinous ring remains attached by one end to the sporocarp.
The antherozoids enter gelatinous envelope and reach to the archegonium.
Useful Notes on the Life History of Marsilea (4960 Words)
The mucilage ring is present in the form of two masses, one in the dorsal and the other in the ventral sides. It straightens and behaves as sporophore. Inner to the cortex there is single layered endodermis. Although the sporocarps of Marsilea are thought to rarely open in nature without the help of bacteria, they can be forced to rupture and expose the sori chains by cutting away an end piece and emersing the entire structure in water marsiela approximately one hour.
The dorsal mass is more prominent than transversely along with their two layered inducia. Each spore mother cell divides meiotically producing a tetrad of 4 haploid spores. The apical cell divides by three vertical divisions so as to form 3 lateral cells surrounding a central cell or archegonial initial Fig.
The marsilez divides to form an upper ventral canal cell and a basal egg. Hypodermis consists of two layers of radially elongated palisade like cells. The decaying of the wall of the sporocarp takes place due to bacterial action and thus the sporangia and spores are liberated.
Under some unfavourable circumstances the subterranean branches of the rhizome form tubers.
It is of protostelic type and occupies the central position. 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. Yccle is somewhat triangular in outline and is of protostelic type i.
According to this hypothesis, the sporocarp is the modification of the whole leaf lamina and petiole where the marginal cells of the leaf develop into sporangia instead of leaflets. In the axil of each receptacle a flap-like indusium is formed Fig. This gelatinous ring bears sori and is known as sorophore.
It divides transversely into an outer and inner cell Fig.
Marsilea: Habitat, External Features and Reproduction
Phloem is externally surrounded by a single layer of parenchymatouspericycle which, in turn, is bounded by a single layered endodermis. The sporocarp of Marsilea has been interpreted as a lateral modified segment of the leaf.
This marginal cell is situated on the inner face of the leaf and is being differentiated only after the apical cell of the leaf has cut off segments. Each neck initial divides by an oblique wall forming a short neck comprised of two tiers of four cells each. One or more adventitious roots come out from each node on the underside of the rhizome. It is made of thin walled cells parenchymatous. It cuts off a pair of segments.
According to BowerBusgenCampbell leaf segment or laminar hypothesis—the sporocarp has been interpreted homologous with a modified fertile segment from the lower part of a leaf. The entire gelatinous ring is cut vertically and it appears as a complete ring around the sori. Their number also varies from species to species. The outer region consists of large air spaces or lacunae separated by septa from each other the inner zone of the cortex consists of a few layers of sclerotic cells.
He was of the opinion that the body of the sporocarp represents the two distal leaf-lefts and the region of 1st and 2nd protuberance represent the remaining 2 proximal leaflets Fig. The sori are situated marignally in the depressions of the lobes. Usually the upper three or four coils consist of blepharoplast and do not bear any flagella. In floating leaflets the stomata dycle present on the upper epidermis but in case of plants growing in mud or moist soil where the if are aerial, the stomata are present both on upper as well as lower epidermis.
The inner cortex is delimited by single layered thick endodermis. The outermost layer is known as epidermis which consists of broad and columnar marsilwa.
Habitat, Reproduction and Life Cycle.
All the species possess a rhizome which creeps on or just beneath the soil surface. Sometimes the pinnas are once or twice deeply dichotomously lobed M. Xylem is present in the form of a complete ring which is surrounded on both sides by a complete ring of inner and outer phloem, pericycle and endodermis.
It is a spherical structure with a short stalk and is present on the top of the receptacle Fig. In this region some of the marwilea cells may be present here and there.
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The inner cells first marsileea transversely to form an upper primary- neck canal cell and lower primary venter cell. The plant body is distinctly differentiated into rhizome, leaves and roots Fig. Two main views have been put forward by different morphologists to explain the morphological nature of the sporocarp of Marsilea which are discussed below: This is a question and marsila forum for students, teachers and general visitors for exchanging articles, answers and notes.
From the dorsal vein, lateral branches are given alternatively right and left, at right angle to the dorsal vein which supplies laterally Fig. The rest of the basal portion of the megaspore mrsilea granular starch, oil globules and albuminous substances. It is differentiated into three regions: A small neck 2 tiers of 4 cells each is derived from the primary cover cell. Just beneath the upper epidermis there is mesophyll differentiated into palisade and spongy tissues.
As the distal part enlarges to form the sporocarp two rows of soral mother cells appear on the ventral side, arising cycke from the marginal cells of the earlier stage.