The pteridophytes are an economically important group of plants. Pteridophytes, paleobotany, environmental biology and ecosystem management. 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. Most pteridophytes are terrestrial and grow in moist and shady places while some flourish well in open, dry places especially in xeric conditions. The classes in this division represent some of the oldest lineages of land plants. However, the pteridophytes differ from mosses and seed plants in that both generations are independent and free living. Occurrence and evolution of pteridophytes biology boom. The distinction between main stems and strongly branched lateral stems evident in species such as p. 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 and alternation of generation. They are psilopsida, psilotopsida, lycopsida, sphenopsida, pteropsida and progymnospermopsida. The pteridophytes are known to be of high economic importance. 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. Publication date 1950 topics pteridophyta, karyokinesis publisher. Pdf on apr 18, 2002, paul kenrick and others published the telome theory find.
The different species of selaginella are grown as the garden plants. Pteridophyta objective type questions pdf download. Pteridophytes introduction, authors and addresses, systematic list, glossary, and key to tribes. Pteridophyta is designed to fulfill the needs of undergraduate and postgraduate students of botany. The pteridophytes are vascular plants plants with xylem and phloem that produce neither flowers nor seeds, and are hence called vascular cryptogams. All pteridophytes have a true alternation of generations, in which a dominant sporophyte generation produces spores through meiosis, and a free living gametophyte generation forms gametes egg and sperm by mitosis. Les sporophylles, portant les microsporanges, sappellent des microsporophylles et celles, portant les macrosporanges, des. The life cycle of pteridophytes is probably best exemplified by the general life cycle of the fern. Tippo 1942 considered tracheophyta to include pteridophytes and spermatophytes. 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. This is commonly interpreted in terms of the more highly specialized leaves of the leptosporangiate ferns as corn.
Pteridophytes definition of pteridophytes by medical. Haeckel 1866 called these groups of plants as pteridophytes because of their pinnate or featherlike fronds leaves. The telome theory, therefore, gives a satisfactory explanation of the evolution of leaves, and of sporangiophores, in this group. Pteridophytes general characters and life cycle of ferns email. Similar to the life cycle of seed plants, the pteridophytes also involves the alternation of generations in its life cycle.
Stelar evolution in pteridophytes ppt types of steles and its evolution in pteridophytes ppt what is stele. Stelar theory, components of stele, different types of steles in plants, protostele. Pteridophytes are a group of plant species that have grown on this earth for over millions of years. Ferns have a life cycle that alternates from a mature adult to an immature fern. The sterile gradually flattened while the fertile telome had a gradual reduction of the basal sterile portion, with the result, the sporangium came to lie on the leafy appendage below fig. Pteridophyta characteristics, life cycle, classification. Ferns can be used to illustrate the life cycle stages common to all pteridophytes. Engler 1886 suggested the term embryophyta to include bryophytes, pteridophytes, and spermatophytes.
International research botany group 2017 international. This thoroughly revised edition, besides retaining almost all topics of the first edition, now also discusses topics like economic importance of pteridophyta, some characteristic features of pteridological divisions, some more rhynophytes, trends of evolutionary specialization in psilophytes, a note on silurian and pre. Ferns are known to have an attractive foliage and therefore, they are grown as ornamental plants in gardens and homes. The body of the sporophyte is well differentiated into roots, stem and leaves. Floristic composition of alabama piedmont floodplains across a gradient of stream channel incision. Telome and the evolution of the independent sporophyte among pteridophytes. Calamophyton, protohyenia and hyenia was a long way from the theoretical ancestral type. The pteridophytes spore bearing vascular plants have been around for 408 milloin years. 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. According to telome theory, a megaphyllous leaf originates as per the following steps. This theory is based on fossil record and synthesizes the major steps in the evolution of vascular plants. Pteridophytes differ from mosses and seed plants in that both generations are independent and free living, although the sporophyte is generally much larger and more conspicuous. This pdf version does not have an isbn or issn and is not therefore effectively published melbourne code, art.
Read the introductory remarks and list of characteristics of the bryophytes p. App download implementation through twitter app card. Content is available under the creative commons attribution share. Zimmermanns telome theory has been widely accepted for over seventy years as the leading explanation for this evolutionary innovation. Challenging the paradigms of leaf evolution new phytologist trust. In this course we are going to use the term pteridophyte to refer to nonseed vascular plants, i. This life cycle is also believed to foster quick reproduction in connection with brief damp periods. Primitive siphonostele protostele with central pith.
Followers of the telome theory believe that in a telome truss, of the two telomes the upper was fertile and the lower sterile. Reproductive biology of pteridophytes springerlink. They are preserved in the form of fossils or coal deposits. 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. This page was last modified on 26 december 2014, at 02. Merits and demerits of telome theory biology 840 words. The phylloids are the prototypes of the microphyllous foliage leaves. Schmidt recognized the two principal types of steles in pteridophytes. The printed version, however, was effectively published on 6 june 20.
Be aware that some people use this term just to refer to ferns. Apospory and apogamy in pteridophytes biology discussion. The origin and early evolution of vascular plant shoots. The sporophyte is the conspicuous and familiar plant body. The modern classification of pteridophytes have been suggested by many scientist according to the sporne1975 pteridophytes have been classified into six classes.
The term pteridophyte refers to vascular plants with independent gametophytes and motile sperm that are usually classified into 4 divisions that comprise nearly 40 families. Pteridophyta have life cycle known as metagenesis with two generations, they are sporophyte and gametophyte generations. Stelar evolution in pteridophytes linkedin slideshare. 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. Natural apogamy is common in ferns like dryopteris, adiantum, osmunda, pteris etc. Pteridophytes ferns and lycophytes are free sporing vascular plants that have a life cycle with alternating, free living gametophyte and sporophyte phases that are independent at maturity.
The telome theory of leaf evolution proposed that transformative evolutionary processes of unequal branching overtopping, rearrangement of lateral branches into a single plane planation and infilling of spaces between branches with laminar tissue webbing generated euphyllophyte leaves. Some of the characters of pteridophytes are as follows. The dominant theory of leaf evolution is the telome theory zimmermann, 1952, which suggests that megaphylls arose by overtopping, planation and webbing of subsets of shoots within a. Apospory is the development of unusual diploid gametophyte from the vegetative parts of sporophyte and not from the spores. This assessment will assess how well you understand the life. Compound sporangiophores, like those of equisetum, are syntelomes. Zimmermanns telome theory of megaphyll leaf evolution. Before considering the telome theory itself, it is desirable to point. Download objective type questions of pteridophyta pdf visit our pdf store. There are no page or colour charges and a pdf version will be provided for. The sexuality of pteridophytic gametophytes can be classified as follows.
Problems of cytology and evolution in the pteridophyta by manton, i. The bryophytes are a group of simple land plants which in many ways are an evolutionary dead end. Pteridophyta mcq multiple choice question and answer pteridophyta mcq with detailed explanation for interview, entrance and competitive exams. On leafarchitecture as illuminated by a study of the pteridophyta. They formed the dominant part of the earths during palaeozoic and mesozoic periods. Apogamy is the development of an unusual haploid sporophyte from the gametophyte without the fusion of gametes. The pteridophytes occupy an intermediate position between the bryophytes and gymnosperms. Pteridophyte definition of pteridophyte by merriamwebster. 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. The dominant theory of leaf evolution is the telome theory zimmermann, 1952. There are about eleven thousand different species of pteridophytes, making them the most diverse land plants. Some pteridophytes are aquatic and some are epiphytes.
However, the growth habit of the earliest members e. The lycopodopsida clubmoss class was the first branch of the evolutionary tree. The true story seems to be lost in antiquity and perhaps will never. It envisages that firstly, instead of the primitive equal dichotomous branching of the stem, there developed a main axis with lateral side branches. Thus, free water is not required for swimming sperm. The current trends in the subject are explained in a simple, lucid and understandablewriting style. According to zimmermann, these telomes or telome trusses of primitive rhynia type of vascular plants have been subjected to certain evolutionary processes in varying degrees among the various taxonomic groups. Pteridophyta in the broad interpretation of the term are vascular plants that reproduce via spores. The telome theory offers one explanation for the nature of the aerial. Basic types of steles protostele central xylem, surrounding phloem.
1345 1036 1087 1164 1196 1542 164 908 778 440 377 1262 107 605 548 521 114 336 688 732 1456 222 634 1307 991 1136 966 907 271 1270 954 884 81 318