Habit and Habitat of Marsilea 2. External Features of Marsilea 3. Internal Structure 4. Reproduction 5.

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No Downloads. Views Total views. Actions Shares. Embeds 0 No embeds. No notes for slide. Marsilea structure and reproduction 1. It is common in the temperate regions. It grows in fresh water ponds and ditches in Punjab.

Marsilea quadrifolia and Muni lea minuta are commonly found in Pakistan. It is differentiated into roots, rhizome and leaves. Rhizome: The stem is in the form of a rhizome. Rhizome has unlimited growth. Therefore, it covers a very large area. The rhizome is dichotomously branched. It has nodes and internodes. A number of adventitious roots arise at each node on the ventral side. But a single leaf arises at each node from the dorsal side.

Leaves: The leaves are compound. Each leaf has a long petiole and four :carats. The kallets are arranged in cross-like manner at the tip of the petiole. Each leaflet is triangular. Veins form reticulate arrangement Stomata arc located on the dorsal side and ventral side of the leaflets. Internal Structure of the Rhizome Internally the rhizome is composed of epidermis, cortex and central stele. Epidermis: It forms outer covering. Cortex: The cortex is wide.

Its peripheral part consists of parenchymatous cells. Ring of a large air chambers are present around this peripheral portion. This portion is called aerenchyma. It stores air. The inner portion of the cortex is composed Sclerenchymatous cells. Endodermis is present inner side of the cortex.

The stele in Marsilea is of amphiphloic solenostele. It has pith in the centre. Protoxylem groups are exarch in position. Internal structure of leaf Both surfaces of the leaf are bound by epidermis. Epidermis is covered by cuticle. It has sunken stomata. Mesophyll cells are present between both epidermises. Mesophyll cells are differentiated into palisade and spongy cells. Single vein passes through each leaf. Reproduction Sporocarp Marsilea plant is heterosporous. The megaspores and microspores are produced in megasporangia and microsporangia.

Both types of sporangia are found within the same sorus. The sari are produced in hard fruit-bodies called sporocarps. The sporocarps are attached to the base of petioles by short stalks peduncles. Sporocarp is bean shaped. It has hard and stony wall capsule. Its wall has single vascular bundle. The sporocarp has two inner chambers. Each chamber has a row of sori. The sori of two rows alternate with each other. The wall of each sorus is formed by its own indusium.

Each sorus contains a row of megasporangia and several microsporangia. A large placenta is produced on the inner side of the wall in the young sporocarp. The placenta of two sides alternate with each other. Megasporangia and microsporangia are produced on the same placenta. Each placenta is covered by its own individual indusium.

Megasporangia mature earlier than the microsporangia. Each megasporangium contains a single megaspore on maturity. But each microsporangium contains several microspores. All the tissues except indusia gelatinized in mature sporocarp. Development of the Sporocarp It is believed that the sporocarp is a single folded pinna. This pinna has single vascular bundle. Receptacles or placentas are produced on the ventral side of this pinna. These receptacles bear sporangial initials.

Each receptacle with the developing sporangia forms a An outgrowth is produced towards the midrib side of pinna. This covering is known as the indusium.

The two sides of the pinna meet at the margin. It completely encloses the developing son. The hardening of cells in the wall gives rise to the bean shaped sporocarp. Dehiscence of sporocarp: The mature sporocarps open after two or three years.

The stony wall decay and open the sporocarp. The inner gelatinous material absorbs water and swells. It splits the sporocarp into two valves. The gelatinous cord or sporophore absorbs water and swells. The spores remain viable for a very long period.



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