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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Anatomy of Marsilea With Diagram Pteridophyta. Spore mother cells 2n undergo meiotic division to form 32 cyclr 64 haploid spores n. Simultaneously, the central cell divides into two cells, a small primary canal cell and a large primary venter cell. Ilfe spores within the sporocarp may remain viable 20 to 30 years and sometimes upto 50 years.
About two or three hours lfie of the beginning of the spore germination, the nucleus divides which is soon followed by a transverse division.
Each vascular bundle is separated from the mesophyll tissue by a layer of endodermis. In some species the teeth are very prominent, e. The sporocarps are borne on short peduncles above the base of the petiole. They are hydrophytic or amphibious plants. Gupta and Bhardwaja have recorded about ten species of Marsilea from our country.
Marsilea: Habit, Structure and Reproduction
The young parts of the leaves of M. Protoxylem patches are present at both the ends lifd one or more metaxylem in the centre. In the dry conditions certain branches develop from the rhizome, which swell because of the storage of food material, and are termed as tubers. This consists of a sclerotic zone. The leaf-segment or laminar hypothesis is supported by several workers and seems to be more correct.
Two sister cells of outer side develop into cotyledon and stem and the other two of inner side develop into the foot and root of the embryo. It is somewhat oval structure with a long stalk and is present laterally on the receptacle.
They are cork-screw like in shape. The sporocarp of Marsilea develops from a marginal cell of a very young leaf. In the inner region of the sporocarp only two chambers of sori are seen surrounded by separate indusia. This gelatinous ring bears sori and is known as sorophore. The zygote is the mother cell of the next sporophytic generation.
It can be split open in the dorsiventral plane into two halves valves.
Useful Notes on the Life History of Marsilea (4960 Words)
In the pife species e. In the region here lateral vein forks, arises a placental bundle which too branches dichotomously. This region may be considered the middle cortex. A fully elongated sorophore is a long gelatinous cylinder 15 to 20 times longer than the length of the sporocarp.
In the central region of the petiole there is stele which is more or less triangular in outline. The morphological nature of the sporocarp of Marsilea has been controversial. Puri and Garg suggested that the leaf consists of single pinna consisting of 4 pinnules. These lateral veins are given off alternately right and left.
It has a single layered jacket followed by two layers of tapetal cells. The leptosporangiate differ from other ferns in having a sporangium with a jacket layer one cell in thickness. In Marsilea vestita the zygote divides for the first time after fertilization only two or three hours later.
The sporocarp bursts open only in water in valvecular manner along the ventral side and apex. In this article we will discuss about: The structure of the wall of sporocarp and the gelatinous ring is the same as in transverse section. Thereafter, there is a ring of xylem which is surrounded by the successive rings of outer phloem, outer pericycle and outer endodermis. Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top.
The archegonial initial divides by a periclinal wall forming an outer primary cover cell and an inner central cell Fig. Just beneath the upper epidermis there is mesophyll differentiated into palisade and spongy tissues.
The apical cell divides periclinally producing an outer cell, the jacket initials and an inner archesporial cell. All the four segments divide by anticlinal divisions several times giving rise to a one-celled thick vegetative tissue. The apical cell cuts off basal cell but this is very much doubted because of the lack of evidence in support of it.
Many antherozoids are attracted towards the funnel shaped structure of megagametophyte. Each sorus appears to be formed in a cavity and is surrounded by a delicate, membranous indusium. The leaves are compound. On the maturation of the archegonium the neck canal cell or cells and the venter canal cell disintegrate and the archegonial neck remains open. The marginal cells here develop sporangia instead of lamina.
Marsilea: Habitat, External Features and Reproduction
The young sporophyte has a well-developed primary root and leaf. Each primary androgonial cell divides to form 16 androcytes Sperm mother cells and finally metamorphosises into antherozoids. The sori reveal many megasporangia and only two or three microsporangia at the sides.