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