On the basis of their anatomy jeffrey in 1902 divided the vascular plants into two types or stocks. Some of the characters of pteridophytes are as follows. They are differentiated into micro and megasporangia. Unlike the bryophytes, these plants are in the mainstream of land plant evolution and eventually gave rise to the seed plants. Heterospory is a condition of the production of more than one type usually two of spores in a single plant. In this article we will discuss about heterospory and seed habit in pteridophytes. A few pteridophytes are aquatic while still others are. There is further elaboration of the megasporangium so as to enable it to be an ideal starting point for the development of a new plant. Importance of heterospory and seed habit of ferns 581 words. Evolutionary significance of heterospory and seed development in. Secondary growth woody plants herbaceous plants habit. The current trends in the subject are explained in a simple, lucid and understandablewriting style. As with all plants, in pteridophytes, meiosis is sporic, meaning that cells of the sporophyte undergo meiosis and generate spores that.
The sporophyte is the conspicuous and familiar plant body. According to rashid 1976 only 9 genera of pteridophytes are heterosporous. Sharma 2000 reported the ethnobotanical uses of ferns from rajasthan, india. However, there are some pteridophytes which produce two different types of spores differing in size. A seed ovule may be defined as an integumented indehiscent megasporangium. They also studied the use of pteridophytes as a vegetable and herbal medicine.
As in seed plants, the greatest diversity of pteridophytes is found in the tropics, with only about six hundred species adapted for life in temperate climates. Pteridophyte definition is any of a division pteridophyta of vascular plants such as a fern that have roots, stems, and leaves but lack flowers or seeds. The entire plant of this species is used as medicine in ayurveda, sidha and unani. Heterospory and seed habitat origin of seeds and seed habitat in vascular plants from heterospory heterospory is the production of two or more types of spores. The condition of heterospory in selaginells constitute one of the very important phases in the evolution of the plants.
They form a conspicuous element of the earths vegetation and are important from evolutionary point of view as they show the evolution of vascular system and reflect the emergence of seed habitat in the plants. Three major evolutionary trends were important for the transition from the seed ferns to the gymnosperms, from the spore to the gymnosperm seed. Some examples of heterosporous pteridophytes are selaginella, azolla, marsilea, salvinia, isoetes. Read the introductory remarks and list of characteristics of the bryophytes p.
In most lower plants like algae fertilization takes place outside the plant body. Pteridophyte definition of pteridophyte by merriamwebster. The seed habit is the most complex and diverse means of sexual reproduction in vascular land plants. Fertilization with a pollen tube, as well as pollination, are not present in pteridophytes but are in gymnosperms. The sexuality of pteridophyte gametophytes can be classified as follows. Heterospory and seed habit in pteridophytes botany. Pteridophyta is the most highly evolved group among the cryptogams. Heterospory and seed habit in pteridophytes ferns plant. Pteridophyta characteristics, life cycle, classification. Each microsporangium contains a large number of microspores whereas each megasporangium contains usually only. As they produce neither flowers nor seeds, they are referred to as cryptogams.
A pteridophyte is a vascular plant with xylem and phloem that disperses spores. Seed plants include the angiosperms, the conifers, and a smaller assortment of other plants. Phytochemical studies in pteridophytes growing in brazil. Pteridophytes may represent the closest living relatives sister group to the seed plants.
Sporophylls the leaves that bear sporangia are known as sporophylls. Evolution of the seed habit consists of at least two independent problems. Classification of pteridophytes for a long time the division pteridophyta includedthe ferns, lycopods and horsetails. Such peridophytes are known as homosporous and this phenomenon is known as homospory. Once seeds existed, their early pattern of diversification was not one of gradual change in form.
Heterospory and seed habitat in pteridophytes short notes heterospory and seed habitat. Reproduction the sporophytes reproduce by spores which are produced within sporangia. Ethnobotanical studies of 40 pteridophytes species by uddin et al. The book gives a detailed account of the life cycles including morphology, physiology, dispersal mechanisms, stages, etc. The remarkable adaptations of ferns to various disturbances, including their abilities to accumulate toxins in their environment, suggest an important role for ferns in conservation and restoration.
Pteridophyta is designed to fulfill the needs of undergraduate and postgraduate students of botany. A few pteridophytes are aquatic while still others are epiphytes. Evolution of stele in general characteristics and classification ot pteridophytes. A seed is that ovule which contains an embryo developed as a result of fertilization. Heterospory and gametophytic unisexuality are not necessarily evolu tionary antecedents of endospory. There are also some purely aquatic ferns such as water fern or water velvet salvinia molesta and mosquito ferns azolla species. In pteridophytes, majority are homosporous, but selaginella, marselia, salvinia, azolla etc are heterosporus showing tendency towards seed habit. Seed is the ripened ovule with integuments formed after fertilization. Each microsporangium contains a large number of microspores whereas each megasporangium contains.
Pteridophyta teridafata os made from two greek roots that mean winged pteryz. Pteridophytes or pteridophyta, in the broad interpretation of the term, are vascular plants plants with xylem and phloem that reproduce and disperse via spores. Classification of pteridophytes short classification of the ferns pdf. The pteridophytes are an economically important group of plants. Mar 23, 2018 the pteridophytes are an economically important group of plants. Jan 23, 2017 reproduction the sporophytes reproduce by spores which are produced within sporangia. This author lists a total of 671 references, but only one work had been carried out in brazil miraglia et al. Any kind of disturbance in these microclimatic conditions can hinder the growth and evolutionary processes occurring naturally in these plants thereby. Pteridophytes biology encyclopedia plant, body, different. They also encompass a greater range of habit than any other group of tracheophytes. Heterospory and seed habitat in pteridophytes easybiologyclass. Then you can start reading kindle books on your smartphone, tablet, or computer no kindle device required. A textbook of bryophytes, pteridophytes, gymnosperms and paleobotany enter your mobile number or email address below and well send you a link to download the free kindle app.
Unlike the bryophytes, these plants are in the mainstream of land plant evolution and eventually gave rise to the seed. The first vascular plants rapidly diversified to cover the earth. Pteridophytes do not have seeds or flowers either, instead they also reproduce via spores. Even today, many tribal communities and rural populations are dependent heavily upon the natural resources obtained from the surrounding forest regions for treatment of various ailments and diseases.
Most of the pteridophytes produce one kind of similar spore. This has equipped the phanerogams spermatophytes that is, seed bearing plants with the best and most efficient means of. In certain species of selaginella only one megaspore develops within the mega sporangium. The final difference between the two groups is in the roots of both types of plants. Phytochemical studies in brazilian pteridophytes soeder 1985 reported a large inventory of papers that appeared between 1966 and 1984 on the chemical constituents of pteridophytes. Gymnosperms can also have secondary growth of the plant while pteridophytes dont. A textbook of bryophytes, pteridophytes, gymnosperms and.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. These plants posses some of the characteristics which are precursors of the seed habit and these are. Most pteridophytes are terrestrial and grow in moist and shady places while some flourish well in open, dry places especially in xeric conditions. A chemosystematic overview of pteridophytes and gymnosperms. As with all plants, in pteridophytes, meiosis is sporic, meaning that cells of the sporophyte undergo meiosis and generate spores that then develop into the gametophyte via mitosis. Similar to the life cycle of seed plants, the pteridophytes also involves the alternation of generations in its life cycle. Most of the pteridophytes ferns and fernallies show their luxuriant and vigorous growth during the rainy season particularly in the hilly regions usually above 1400 m altitude. Pteridophytes represent an intermediate position between bryophytes and spermatophytes gymnosperm and angiosperm. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Pteridophytes gametophytes and sporophytes of bryophytes. These are selaginella, isoetes, stylites, marsilea, pilularia, regnellidium, salvinia. They are flowerless, seedless, spore producing vascular plant which have successfully invaded the land. Ethnomedicinal uses of pteridophytes of kumaon himalaya. Origin of seeds and seed habitat in vascular plants from heterospory heterospory is a condition of the production of more than one type usually two of spores in a single plant.
The delimitation of families of extant pteridophytes had been very controversial in the past but a consensus has been emerging on overall. Seex pteridophytes, selaginella rupestris is the most successful species that completed first four steps towards seed habit. Heterospory and seed habit in pteridophyts youtube. The sexuality of pteridophytic gametophytes can be classified as follows. In order to overcome this problem, the female gametophyte is heteroslory retained in the megasporangium. Economic importance of pteridophytes,several ferns such as angiopteris, asplenium, marattia, microsorium, nephrolepis, phymatodes, etc.
The sporangia show greater specialization than those of ferns. The delimitation of families of extant pteridophytes had been very controversial in the past but. The sporophyte was the dominant phase of the life cycle of these early pteridophytes. Gymnosperms have a tap root while the pteridophytes do not. Being the first true land plants they include in their bodily features the results of many experiments that nature conducted with the sporophytic plant body on a primordial terrestrial habitat. They form a conspicuous element of the earths vegetation and are important from evolutionary point of view as they show the evolution of vascular system and. In this lesson, well discover the characteristics, classification, and life cycle of the group pteridophyta, which includes plant species like ferns and horsetails.
Examples of heterosporous pteridophytes lifeeasy biology. However, the pteridophytes differ from mosses and seed plants in that both generations are independent and freeliving. Heterosporous pteridophytes are the plants that produce two types of spores i. In pteridophytes, gametes are produced via mitosis from special cells of the gametophyte. Some pteridophytes are aquatic and some are epiphytes. The different species of selaginella are grown as the garden plants. Since their first appearance in the late devonian, seed plants have come to dominate almost every terrestrial ecosystem. Because pteridophytes produce neither flowers nor seeds, they are. Experimental studies of bryophytes, pteridophytes and gymnospersms are discussed from recent literature. Pteridophytes ferns and fern allies the plant list.
In some species of homosporous ferns, gametophytes developing from. In some pteridophytes the sporangia develop on stems i. Most pteridophytes are terrestrial plants and thrive well in abundant moisture and shade while some flourish well in open, dry situations especially in xeric conditions. Thus, these characteristics make them horticulturally important plants. Retention of the female gametophyte within the megasporangium on the parent plant for proper parental care of new embryo. Heterospory and origin and evolution of seed habitat in land plants pteridophytes. A concept based exclusive material pteridophytes, gymnosperms. Pteridophytes differ from bryophytes in that the sporophyte is branched and generally much larger and more conspicuous, and from seed plants in that both generations are independent and freeliving. Ethnomedicinal uses of pteridophytes of kumaun himalaya upreti, et al. The adoption of heterospory and the retention and germination of a single megaspore within megasporangium to form a female gametophyte, led to the phenomenon of seed habit, a characteristic feature of the spermatophytes.
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