Pteridology, gymnosperms and palaeobotany uttarakhand open. This is a portion of the telome theory as proposed by zimmermann 1952 and 1959, who proposed that all of the main plant organs can be derived from simple rhynialike axes called mesomes sterile axes and telomes fertile axes. Stelar theory, components of stele, different types of steles in plants, protostele. Since this wall is periclinal each initial cell is divided into an outer and inner daughter cell. Various animals use the fronds as food while birds and small creatures use the plants for cover. 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. It is the remains of these giant pteridophytes that would over eons become the fossil fuels we use today. Content is available under the creative commons attribution share. Read the introductory remarks and list of characteristics of the bryophytes p. According to telome theory, the sporophylls originated by the modification of telomes in a telome truss. Basic types of steles protostele central xylem, surrounding phloem. Pteridophytes were dominant land plants during the carboniferous era and a major source of todays coal and oil. Despite early success in pteridophytes and gymnosperms, the telome theory never. Extant pteridophytes are cosmopolitan but are much better represented in the humid tropics, with only a few families e.
The telome theory attempts to explain the origin and development of complex plant organs from more basic multicellular units called in developmental genetics and plant evolution 2002 eds q. Compound sporangiophores, like those of equisetum, are syntelomes. Pteridophytes pteridophtyes are a phylum of plants. However, the pteridophytes differ from mosses and seed plants in that both generations are independent and freeliving. One weakness of the telome theory zimmermann, 1952 is that, although processes of organ evolution are well explained, their developmental basis remains unclear kenrick, 2002. Besides having various medicinal properties, the pteridophytes are also employed for a variety of commercial and environmental purposes. Botany for degree pteridophyta top results of your surfing botany for degree pteridophyta start download portable document format pdf and ebooks electronic books free online rating news 20162017 is books that can provide inspiration, insight, knowledge to the reader. According to telome theory, a megaphyllous leaf originates as per the. The sporophyte is the conspicuous and familiar plant body. Characteristics of pteridophytes, morphology of pteridophytes, reproduction of pteridophytes, homosporous and heterosporous pteridophytes, megaspore and microspores, gametophytes of pteridophytes, fertilization, zygote and embryo of pteridophytes, life cycle.
Clubmoss, horsetail and fern trees dominated earths land vegitation for more than 100 million years. They proposed the stellar theory, according to which the root and stem have the same basic structure consisting of two fundamental units the cortex and the central cylinder. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The pteridophytes occupy an intermediate position between the bryophytes and gymnosperms. Mainly there are two theories to account for the origin of leaves. Buy isbn9781403930309 at 16% discount by macmillian india ltdnew delhi. Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. Engler 1886 suggested the term embryophyta to include bryophytes, pteridophytes, and spermatophytes. Similar to the life cycle of seed plants, the pteridophytes also involves the alternation of generations in its life cycle. The sporophylls of lycopsids always have a single sporangium borne on their adaxial surface surface close to the axis. Sporophylls the leaves that bear sporangia are known as sporophylls.
Pteridophytes or pteridophyta, in the broad interpretation of the term, are vascular plants plants with xylem and phloem that reproduce and disperse via spores. Some of the characters of pteridophytes are as follows. Some other uses are ferns provide natural vegetation thats important to both wildlife and birds. The telome theory proposes instead that both microphylls and megaphylls. Sharma 2000 reported the ethnobotanical uses of ferns from rajasthan, india. The steps leading to the formation of a megaphyll are given in figure 11. Problems of cytology and evolution in the pteridophyta by manton, i. The sporophyte was the dominant phase of the life cycle of these early pteridophytes.
Pteridophyta is the most highly evolved group among the cryptogams. All pteridophytes have a true alternation of generations, in which a dominant sporophyte generation produces spores through meiosis, and a freeliving gametophyte generation forms gametes egg and sperm by mitosis. According to telome theory first proposed by zimmermann 1930, 1938, primitive pteridophytic shoot was naked and dichotomously branched. The further elaboration of the microphyll with branched tips in early herbaceous lycopods leclercquia, protolepidodendron, estinnophyton can only be explained by telome theory. In pteridophytes, gametes are produced via mitosis from special cells of the gametophyte.
Most pteridophytes are terrestrial and grow in moist and shady places while some flourish well in open, dry places especially in xeric conditions. Relate telome theory with the origin of higher pteridophytes from the lower pteridophytes. Unlike the bryophytes, these plants are in the mainstream of land plant evolution and eventually gave rise to the seed plants. These are the telome theory and the enation theory. The first vascular plants rapidly diversified to cover the earth. They are psilopsida, psilotopsida, lycopsida, sphenopsida, pteropsida and progymnospermopsida. The time period of the giant pteridophyta forests is known as the carboniferious period. Mendels laws of heredity, chromosomal theory of inheritance, meiosis and mitosis, linkage and crossing over types, mechanism and significance, nucleic acid as genetic material structure, replication, genetic code and translation, mutation spontaneous and induced, sex. The different species of selaginella are grown as the garden plants. Pteridology, gymnosperms and palaeobotany bscbo103 unit schedule block1 pteridophytes unit1general features, classification, telome theory, stelar system, heterospory and life cycle unit2structure and reproduction in rhynia and selaginella unit3structure and reproduction in equisetum and adiantumunit4structure and reproduction in marsilea and azolla. In the classical concept of a microphyll, the leaf vein emerges from the. The degree of master of science in plant science aims to introduce the students to various aspects of plant biology. Ebook botany for degree pteridophyta as pdf download portable. Problems of cytology and evolution in the pteridophyta.
According to telome theory the earliest levees are flattened telomes or phylloids, and the sporangium in all cases, together with its stalk or sporangiophore, is a fertile telome. The modern classification of pteridophytes have been suggested by many scientist according to the sporne1975 pteridophytes have been classified into six classes. The sexuality of pteridophytic gametophytes can be classified as follows. At the end of the course, the students are expected to have good working knowledge in the field of plant science. Tippo 1942 considered tracheophyta to include pteridophytes and spermatophytes.
The phylloids are the prototypes of the microphyllous foliage leaves. Merits and demerits of telome theory biology 840 words. Pteridophytes biology encyclopedia plant, body, different. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as cryptogams, meaning that their means of reproduction is hidden.
Pteridophytes, paleobotany, environmental biology and ecosystem management. A pteridophyte is a vascular plant with xylem and phloem that disperses spores. Some pteridophytes are aquatic and some are epiphytes. The telome theory can be applied to interpret the evolution of a synangium of psilotum. 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. While telome theory accounts for the origin of both microphylls and megaphylls, enation theory explains only the origin of microphylls. In plant anatomy and evolution a microphyll or lycophyll is a type of plant leaf with one single, unbranched leaf vein.
It envisages that firstly, instead of the primitive equal dichotomous branching of the stem, there developed a main axis with lateral side branches. A concept based exclusive material pteridophytes, gymnosperms. The theory that the leaves megaphylls of ferns and seed plants evolved by the modification of terminal branches telomes of stems. Followers of the telome theory believe that in a telome truss, of the two telomes the upper was fertile and the lower sterile. They also studied the use of pteridophytes as a vegetable and herbal medicine. The pteridophytes are an economically important group of plants.
Pdf on apr 18, 2002, paul kenrick and others published the telome theory find, read and cite all the research you need on researchgate. 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 sporangium in all pteridophytes is initiated by the laying down of a crosswall in a superficial cell or a group of cells. In some pteridophytes the sporangia develop on stems i. Schmidt recognized the two principal types of steles in pteridophytes. The empirical basis of botanical systematics has been broadened far beyond the realm of macromorphological traits on which systematists have based their decisions for more than 200 years. Stelar evolution in pteridophytes ppt types of steles and its evolution in pteridophytes ppt what is stele. They are the vascular plants those having xylem and phloem tissues that reproduce by releasing spores rather than seeds, and they include the highly diverse true ferns and other graceful, primarily forestdwelling plants.
Ferns can be used to illustrate the life cycle stages common to all pteridophytes. Ethnobotanical studies of 40 pteridophytes species by uddin et al. Jan 23, 2017 reproduction the sporophytes reproduce by spores which are produced within sporangia. Pteridology, gymnosperms and palaeobotany bscbo103 unit schedule block1 pteridophytes unit1general features, classification, telome theory, stelar system, heterospory and life. The telome concept has been used in understanding the origin and evolution of the following major groups of plants.
Reproductive biology of pteridophytes springerlink. Pteridophyta characteristics, life cycle, classification. This page was last modified on 26 december 2014, at 03. Pteridophytes general characters ppt general characteristics, life cycle and reproduction of pteridophytes ppt what are pteridophytes. The overtopping, reduction and syngenesis have combined to produce a synangium of psilotum fig. Primitive siphonostele protostele with central pith.
1256 1671 1530 55 696 1002 582 1236 696 1201 856 1643 132 977 154 103 295 900 283 494 1628 576 718 378 1276 1537 167 344 1075 123 404 1372 770 977 681 739 528 129 227 16