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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Formation of inoculations takes place due to undifferentiated growth of soral mother cells and their derivatives. In the earlier stages of its development it is soft and green but later on it becomes sufficiently hard and brown in colour. The family includes the living genera-Marsilea, Pilularia and Regnellidium. The adjoining cells of the megagametophyte divide periclinally forming a two to three-celled thick calyptra. Marsilea is heterosporous i. The outer exine is covered by a thin layer called perispore.
It cuts off a pair of segments. They are cork-screw like in shape. There is a definite number of spores within a sporangium.
Lifd young sporophyte has a well-developed primary root and leaf. In majority of cases the peduncle or stalk of the sporocarp is unbranched and bears a single sporocarp at its apex. About 9 species have been reported from India.
This large cell functions as store house of food material. The structure is termed as tuber and is capable of tiding over the unfavourable conditions.
The opening of the V is always towards the axis, i. One of the superficial cells acts as a sporangial initial. This apical cell cuts off two cells from its each face which helps in the formation of stalk. Marsilfa submerged species, however, the mesophyll is not differentiated into palisade and spongy parenchyma.
The mucilage ring is present only on the dorsal side. The cortex is differentiated into outer and inner cortex. It takes place by means of tubers which are produced in dry conditions from the rhizome. The initial cell divides periclinally transversely into an outer and an inner cell. The V-shaped mass of xylem is surrounded by phloem and single-layered pericycle successively.
cycls The oospore is the initial states of sporophytic generation. In the centre of the stele there is typical diarch and exarch structure with a diametric plate like strand of xylem. The advocates of the leaf segment theory interpret it in various ways.
In the inner region of the sporocarp only two chambers of sori are seen surrounded by separate indusia. This delay is probably due to the imperviousness of the hard sporocarp wall. Stomata are present in the upper epidermis in submerged species or on both the upper and lower epidermis in terrestrial madsilea amphibious species.
A mature megagametophyte is lifw by a broad, ovoid gelatinous zone which there in a watery funnel shaped opening directly upon the archegonium. It can be differentiated into three zones—outer epidermis, middle hypodermis and inner parenchymatous zone. All the species possess a rhizome which creeps on or just beneath the soil surface.
At night the pinna are folded upwardly. Useful Notes on the Structure of Nucleus Words. They are heterosporous aquatic ferns.