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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This order includes a single family, Marsileaceae. The family includes the living genera-Marsilea, Pilularia and Regnellidium. They are heterosporous aquatic ferns. The sporangia of these are produced within special structures known as sporocarps.
Oife sporocarp possesses many sori which bear microsporangia and megasporangia. The sori are gradate, i. There are about 65 marssilea of Marsilea distributed all over the world. They are more commonly found in tropical regions, such as, Africa and Australia. Gupta and Bhardwaja have recorded about ten species of Marsilea from our country. About six species of Marsilea are known to occur in the United States. They are hydrophytic or amphibious plants.
They grow rooted in the mud of marshes and shallow pools. Marsilea vestita and some other species grow in shallow ponds. A single plant of M. An Australian species M. The species of Marsilea possess a rhizome which creeps on or just beneath the surface of the soil.
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The rhizome is slender, branched and possesses nodes and internodes. The leaves are borne alternately along the upper side of the rhizome usually at the nodes. One or more adventitious roots mzrsilea out from each node on the underside of the rhizome.
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. The leaves are borne alternately along the upper side of marwilea rhizome at the nodes. The leaves possess circinate vernation typical of most Filicales ferns.
The young parts of the leaves of M. The leaves of submerged plants possess long flexible petioles and leaf lamina that float on the water surface.
Useful Notes on the Life History of Marsilea (4960 Words)
When the 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. The leaves are compound. The lamina of each leaf is divided into four leaflets pinnae arising from the apex of the petiole.
Division of a leaf-blade into four leaflets results from two dichotomies arising in close marsilsa to each other. According to Puri and Garg the leaf of Cyce consists of single leaflet bearing four pinnules and text-books. The veins of each pinna are dichotomously branched and have numerous cross connections resulting in close reticulum of veins. The shape of pinnae varies from obovate to obcuneate.
The margin also varies from entire to crenate, e. The leaflets may be once or twice deeply lobed dichotomously, marsioea. At night the pinnae of aerial leaves become folded upwards and exhibit the sleeping movement.
The sporocarps are borne vycle short peduncles near the base of the petiole. In majority of cases the peduncle or stalk of the sporocarp is unbranched and o a single sporocarp at its apex.
Marsilea quadrifolia possesses dichotomously branched peduncle, which bears two to five sporocarps. One or more adventitious roots are borne at each node on the underside of the rhizome. The adventitious roots may arise even from internodes, e.
The roots of M. ,ife rhizome of Marsilea possesses an amphiphloic siphonostelic vascular cylinder. The outermost layer is the single- layered epidermis without any stomata. The cortex is differentiated into outer and inner cortical regions. The outer cortical oife consists marilea compact parenchymatous tissue.
This region may be one to several celled in thickness. Just beneath this the cortical region contains large lacunae oife air spaces aerenchyma. The lacunae are separated from each other by one layered parenchymatous septa. This region may be considered the middle cortex. Internal to this region the inner cortex is found. This consists of a sclerotic zone. The cells consisting this region are thick-walled sclerenchymatous cells fibres. Beneath this region the cortex again consists of compact parenchymatous tissue acting as storage tissue containing starch in them.
Some of the tannin cells may be found in this innermost region. The stele is amphiphloic siphonostele. All species possess the siphonosteles externally and internally limited by a single layered endodermis. Just beneath the outer endodermis there is a single layered pericycle. In the centre is the pith whose structure depends upon environmental conditions. In submerged species, the rhizomes possess usually a parenchymatous pith, whereas the plants growing on mud have a more or less sclerenchymatous pith.
Outside the pith there is a sindle-layered inner endodermis, inner pericycle and then inner phloem in a continuous succession. Thereafter, there is a ring of xylem which is surrounded by the successive rings of outer msrsilea, outer pericycle and outer endodermis.
Gupta and Bhardwaja reported the mesarch protoxylem in M aegyptiaca. This way, the continuation of different tissue in the amphiphloic siphonostele is as follows-outer endodermis, outer pericycle, outer phloem, xylem, inner phloem inner marsiilea and then inner endodermis.
The internal structure of a petiole as seen in transverse section is as follows— The outermost layer is single-layered epidermis.
Just beneath the epidermis there is hypodermal layer. Then there is other cortex constituting of large air spaces or lacunae aerenchyma separated from each other by septa. The inner cortex is composed of compact parenchymatous cells. In this region some of the tannin cells may be present here and there.
In the central region of the petiole there is stele which is more or less triangular in outline. The stele is surrounded by a single- layered endodermis. It possesses V-shaped mass of xylem with the exarch protoxylem.
The two arms of V are quite separate and somewhat curved from each other. The V-shaped mass of xylem is surrounded by phloem and single-layered pericycle successively. The ends of each arm of V-shaped xylem are protoxylem groups whereas the middle regions of the arms of V consist of large tracheids representing the metaxylem groups.
The opening of the V is always towards the axis, i.
Marsilea: Habitat, External Features and Reproduction
As shown in transverse section of the leaflet, it is bounded by two upper and lower epidermal layers. In the case of floating leaves the stomata are confined to the upper surface but in the case of the plants growing in mud and moist soil, the leaves are aerial, and the stomata are found on both the upper and lower surfaces. Just beneath the upper epidermis there is mesophyll differentiated into palisade and spongy tissues. The vascular xycle are concentric, i.
On the outside mardilea the vascular bundle there is single layered endodermis. Towards lower side there are big air spaces separated by septa. In the transverse section of the root, the epidermis, cortex and stele may be seen. The epidermis is single layered and composed of thin-walled parenchymatous cells.
The cortex of the root is differentiated into two regions. 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. Inner to the cortex there is single layered endodermis. Just beneath the endodermis there is single-layered pericycle. In the centre of the stele there is typical diarch and exarch structure with a diametric plate like strand of xylem.
The phloem bands are found on either side of the xylem plate. The vegetative reproduction takes place by means of specially developed structures known as tubers.
In the dry conditions certain branches develop from the rhizome, which swell because of the storage of food material, and are termed as tubers. These tubers survive in the unfavourable and drought conditions, and on the return of favourable conditions they germinate marislea new plants, e.
The plant is a sporophyte. It bears the special structures known as sporocarps which contain micro and megasporangia in them. The sporocarps are borne on short peduncles above the base of the petiole. In most cases the peduncle is unbranched and bears a single sporocarp at mareilea apex.
The sporocarps may be oval or bean-shaped.
In the earlier stages of its development it is soft and green but later on it becomes sufficiently hard and brown in colour. In majority of the species of Marsilex near the point of attachment of the stalk or peduncle at the base, there are usually one and sometimes more protuberances in the median plane. The raphe is found laterally fused to base of the sporocarp at the end of the peduncle.