Gametophytes While Macro- Or Megaspores on Germination Give

Home , Archaeopteridales, Pleuromeiaceae

D. Characteristic featares of Pteridopbyta : 1. The plant body represents the sporophyte. In the life history of pteridophytes, both the sporophytic and gametophytic generations are independent of each other. Although in Pteridophyta, sporophytes are nutritlonally independent of the gametophyte still they are dependent on gametophyte jor a shortembryonic period. 2. Plantbodiesare provided with well developed true roots (excep tionsfossil Pteridophyta and Psilotum), stems and leaves. Stems and roots have apical growth. Roots are provided with permanent growing point and can grow in length indefinitely. of photosynthetic tissue i.e., chlorophyll bearing cells remain3. mainlyReduction within the Jeaves--hence photosynthesis is also restricted to leaves which are provided with epidermis having stomata and chlorophyl| bearing cells. 4. Sporophytes show well marked tissue differentiation-roots, stems and leaves are traversed by vascular i.e., conducting tissues such as xylem and phloem-hence pteridophytes are also known as vascular cryptogams. 5. Tbe sporophy tes are also known as asexual or spore-producing generations. In Pteridophyta this generation may be either homosporous i.e. bearing one kind of spores which on germination give rise to gametophytes bearing both male and female sex organs (i.e. monoecious or homothallic), or heterosporous where spores are of two kinds--viz, smaller microspores and larger nacro- or megaspores. Microspores on germination produce male gametophytes while macro- or megaspores on germination give rise to,.emale gametophytes-hence heterosporous pteridophytes always produce dioecious or heterothallic gametophytes. 6. Spores are produced within sporangia-in homosporous types, sporangia are of one kind as spores are alike, but in heterosporous types sporangia are of two kinds viz. microsporangia (microsporecontainingsacs) and macro- or megasporangia (macro- or megaspore containing sacs). Sporangia bearing leaves are called sporophyllsin heterosporous pteridophytes sporophylls are also of two types viz., microsporophy!ls(microsporangia bearing leaves) and macro- or megasporophylls (megasporangia bearing leaves). Sporo. phylls in many cases do not differ from the mature foliage leaves and are loosely arranged (some species of Lycopodium, ordinary ferns like Polypodium etc.);in other cases sporophylls are specialised and localised to form a compact structureknown as strobilus (plural: strobili) or cone. 7. Stem and roots of the plant body /.e., sporophyte are provided with stele-a central vascular cylinder of conducting system. For different types of steles in pteridophytes and their evolution refer Plant Anatomy portion, Chapter 5, article 5.9, page 277. E. Life cycle--In the life history of the pteridophytes there is a typical heteromorphic alternation of sporophytic and gametophytic generations-these two generations alternate with each other in a regular succession i.e., sporophyte to gametophyte and gametophyte to sporophyte. The sporophytic PTERIDOPHYTA-INTRODUCTION 821

GeXUal generation is diploid, which results from the union of two haploid metes (i.e,, antherozoid and ovum)--the starting point of this generation he zygote or o0spore (2n). The gametophytic or sexual generation is loid (n) and which results from the formation of haploid spores (the tarting point) produced by the sporophyte-in this type of alternation, Shromosome number is doubled at the time of gametic union and becomes Salved at the time of spore formation showing thereby a cytological alternation of diploid and haploid generations.

SPOROPHYTE 2n (2n Spores J2ygote Meiosis

nEgg

Sperm GAME TOPHYTEn

Fig 1.1-Life cycle of a homosporous pteridophyte.

Among pteridophytes the sporophyte is the dominant generation, as it of the grows to a much very soon becomes independent gametophyte and greater size along with greater degree of morphological and anatomical On the basis of size differences of the spores produced by sporO complexity. In phytes, pteridophytes may be homosporous and heterosporous. hom0 each on germination produces sporous, spores are of same sizes; spore (prothallus) bearing both antheridia and oogonia monoecious gametophyte is same hence the life cycle (Fig. 1.1) of a homosporous pteridophyte basically like that of bryophytes. On the other hand spores produced by hetero are of different sizes such as larger megaspores giving sporous pteridophytes and smaller microspores to female gametophyte bearing only archegonia rise antheridia Therefore the giving rise to male gamatophyte bearing only. Meiosis SPOROPHYTE Microspores 2n

2n Mega- Zygote Spores Meiosis

FEMALE Egg GAMETOPHYTE

MALE GAMETOPH- Sperm -YTE nn

a heterosporous pteridophyte. Fig. 1.2Life cycle of R22 STUDIS 1IN DOTANYy life cycle of heterosporous pteridophytes (Fig.1.2) differ markedly from of homosporous pteridophytes. Itis to be noted, that such size dierehat spore is well marked wherever the gamectophyto 1S fetained within the sDor Sometimes cytological alternation of gederation is hampered due to formation of the the the gametophyte directly rom sporophyte without the production of spores (apospory) and also vegetative cells sporophyte directly from the of the gametophyte without gametic union (apogamy); some times egg cell may develop apogamously into a is known as parthenogenesis. sporophyte-his phenomenon F. Classiication:

According to Smith (1955) i.e. classified as follows Pteridophyta pteridophy tes have been Division I. stem branches only or bothPsilophyta-Sporophyte branches is rootless, consists of and leaves. are borne the tips of branches. Sporangia singly at CLASS I. PsiLOPHYTINAE

Order I. it 4 Psilophytales, contains families. All genera are known from Lower and Upper Devonian. fossils, Order 2. Psilotales, it contains single family Division II. Psilotaceae, e.g.. Psilotum. Lepidopbyta-Sporophyte is into and leaves. Leaves are spirally differentiated root, stem region of leaves near the base. arranged. Sporangia are borne on the adaxial CLASs I. LYcoPoDINAB Order I. Lycopodiales, it 2 dendraceae (inçludes contains families viz., 1. Protolepido. fossil genera, e.g. Protolepidodendr on) and 2. podiaceae (includes living genera e.g. Lycopodium, Lyco. Order 2. Phylloglossum etc.). Selaginellales, it contains 2 families (contains only one living and 2. viz. 1. Selaginellaceae only fossil genus Miadesmia).genus Selaginella) Miadesmiaceae (containing Order 3. it Lepidodendrales, contains 4 1. dendraceae (Lepidodendron), 2. Lepidocarpaceae families viz, Lepido- dendraceae (Bothrodendron) and 4, Sigillariaceae (Lepidocarpon). 3. Bothro i.e. fossils, known from Upper Devonian. (Sigillaria)-all are extinct Order 4. it Isoetales, contains 2 viz., 1. (contains fossil member e.g, families Pleuromeiaceae Pleuromeia) and 2. Isoetaceae (e.g., Isoetes). Division IIl. is and Calamophyta-Sporophyte into stem leaves; leaves are arranged in whorls. differentiated root, sporangiophores. Sporangia are borne on CLASS I. EQUISBTINAR- Order I. Hyeniales, consisting of Calamophyton (fossils). single family Hyeniaccae, e.g. Hyenia, Order 2. Sphenophyllales, it contains single only, e.g, Sphenophyllum (fossil). family Sphenophyllaceae Order 3. 2 2. Equlsetales, containing families vlz., 1. Calamitaceae and Equisetaceae e.g. Equisetites (fossil) and Equlsetum Division IV. (living). Pteropbyta-Sporophyte is differentiated into root, and leaves, leaves are stem of adaxial face of the leaf.spirally arranged. Sporangia arc borne on the margin PTERIDOPAYTA-INTRODUCTION 823 Class 1. FiLICINAB SubclassI. Primofilicales-Sporangia are borne singly at the apex of a leaf. Jacket of sporangia is more than one-cell layer thick. Knowa in fossil condition from Paleozoic.

daceaeOrder (Protopteridium 1. Protopteridales-It and Aneurophyton) includes and two (2) families Cladoxylaceae viz., (1) (Cladoxylon)Protopteri -all are fossils. Order 2. Coenopteridales -It includes three families viz., (1) Zygopteri daceae (Zygopteris), (2) Botryopteridaceae (Botryopteris) and (3) Anacho- ropteridaceae (Anachoropteris and Gyropteris). Order 3.Archaeopteridales-contains one family Archaeopteridaceae, e.g. Archaeopteris tFossil). Subclass II. Eusporangiatae--Sporangia are borne on an outgrowth at abaxial surface of leaf, known as spike, sporangia in sori, formed the of is more than one-cell spores many in a sporangium; jacket sporangium layerthick; knoWn from Carboniferous to present-day. Order 1. Ophioglossales, contains single family Ophioglossaceae, c.g. Ophioglossum. e.g. Marattia. Order 2. Marattiales, contains single family Marattiaceae, are sori and are borne Subclass III. Leptosporangiatae-Sporangaia in on are few a sporangium: marginally or abaxially leaf blade. Spores in one.cell in thickness. jacket of sporangium is of 10 families, beginning from Order 1. Filicales-Thisorder consists Osmunda, Schizaea, and ending in Parkeriaceae; examples are Osmundaceae Dryopteris, Polypodium, Pteris, etc. Gleichenia, Matonia, Hymenophyllum, Marsileaceae, eg. Marsilea. Order 2. Marsileales-Single family Salviniaçeae, e.g. Salvinia, Azolla. Order 3. Salviniales-Single family and all the vasculsr plants (Pteridophyta Eames (1942) and others placed with and Bryopbyta. (1936), Tippo Tracheophyta" cognate Thallophyta Spermatophyta) in a single-division e.g.Psilopsjda_(Psilophytales and Tracheophyta into four sub-divisions Pleuromeiales and They segregated Selaginellales,Lepidodendrales, Psilotales), Lycopsida (Lycopodiales, Equisitales) and Pteropsida (Filicineae, Sphenopsida-(Hyeniales, Sphenophyllales and the Pteridophyta or Isoetales), docs not agrec term and Angiospermae). Bold (957) into four divisions Gymoospermae classiied all the vascular Cryptogams Tracheophyta as a division, rather he Arthropbyta (=Sphenopsida) Microphyllophyta (=Lycopsida), and viz., Psilopbyta (=Psilopsida), term Pteropsida of Eames Tippo. (=Filicinac)-he has abandoned the as a division Pterophyta his the Pteridophyta and however has retained in classification Pichi-Sermoli (1958), 2Sphenopsida,3. Noeggerathiopsida, classes viz., 1.Lycopsida, Die and which includes six Zimmermann (1959) in Phylogenie 5. Psilophy topsida and 6. Filicopslda. in five 4. Psilotopsida, pteridophytes i.e. vascular cryptogams Pffanzenfamilien (Auß. 2) has divided and Pterophyta. der Lycophyta, Sphenophyta, Noeggeratbiophyta divisions such as Psilophyta, in the pteridophytes are grouped has followed a system of classiication which Psilotopsida), Parihar (1962) 2 classes, 0g. Psilophytopsida and divisions viz. Psilophyta (containiog Calamopsida and Into four and Ligulopsida), Arthrophyta (classes ycophyta (classes Eligulopsida Leptosporangiopsida, Protolept osporapgiopsida, phenophyllopsida) and Filícophyta (classes Eusporangiopsida and Primoilicopsida). as published in the 1954 classification of the Pteridophyta cditionReimers' of Engler's Syllabus der Pfianzenfamilien-

Division: PTBRIDOPHYTES A. Sub-division: Psilopbytopsida Order Psilophytales Zosterophyllacear, Paylophy1aceae, Families: Rhyniaccae, Astern xylaceae. STUDIES IN BOTANY 824

B. Sub-division: Psllotopsidaa Order Psilotales Families: Psilotaceae, Tmesipteridaceae. C. Sub-division: Lycopslda Order 1. Protolepidodendrales Familles: Drepanophycaceae, Protolepidodendraceae. Order 2. Lycopodiales Family: ycopodiaceae Order 3. Lepidodendrales Families: romeiaceae.Lepidodendraceae, Bothrodendraceae, Sigillariaceae, Pleu. Order 4. Isoetales Family Isoetaceae Order 5. Selaginellales Family: Selaginellaceae D. Sub-division: Sphenopsldaa Order 1. Hyeniales Families: Protohyeniaceae, Hyeniaceae. Order 2. Sphenophyllales Familiee Sphenophyllaceae, Cheirostrobaceae. Order 3. Calamitales Families: Asterocalamitaceae, Calamitaceae, Order 4. Equlsetales Family Equisetaceae E. Sub-division: Pteropslda a. Class PriMOFILICES Order 1 Cladoxylales Families: Cladoxylaceae, Pseudosporochnaceae. Order 2 Coenoptertdales Families b. Class EusPORANGIATABZygopteridaceae, Stauropteridaceae, Order 1 Marattiales Botryopteridaceae. Families: ceae,Asterothecaceae, Christenseniaceae. Angiopteridaceae, Marattiaceae, Order 2 Ophloglossales Danaea Family Ophioglossaceae c. Class OSMUNDIDAB Order Osmundules Family: Osmundaceae d. Class LePTOSPORANGIATAB Order 1 Flicales Families: Schizaceae, Gleicheniaceae, ceae, Matoniaceae, Dipteridaceae,Hymenophyllaceae, Dicksoniae Order 2 Marsilealestiaceae, Adiantaceae, Polypodiaceae.Cyatheaceae, Dennstacd Families Pilulariaceae, Marsileaceae. Order 3 Salviniales Families: Salviniaceae, Azollaceac. Orlelo of wo.theories BuchPterkidophyta-Regarding as (a) the ogin from algal orlgin and phylogenetic origin of ro and Algae, the latter is (b) Pteridophytaates pteridophytes both are based on the bryophytic origln, the torm related to each other. conalderation that bryophytes 8 ris t PTERIDOPHYTA-INTRODUCTION 825

Some supporters of direct algal origin of pteridophytes consíder that. similarities existing to some extent between certain sections of Algae and Pteridophyta are due to parallel evolution but not due to pàylogeaetic.connection or link between them, Other supporters of algal origin believe.that.the origia was from the brown algae, as this group of algae has similar mofile male gametes resembling those of many pteridopbytes. Fritsch (1945) has suggested that(Chlorophyta) the origin whereof pteridophytes the vegetative from body chaetophoraceous was of an erect 1ype parenchymatous of filamentous type green and algae like Dteridophytes there was an alternation of two generatiops. Scolt (1900), Eames (1936) and others do not advocate the origin of pteridophytes from any particolar section of algæ whereas Church (l1919), Arnold (1947) and others postulate that the osigin of pteridophyies some complex algae inbabiting tidal levels of sea shore and gradually took place from either from Phaeopbyta (brown algae) transmigrating from sea-such evolution was presumed or from Chlorophyta (green algae). Bower (1935), Bryonhytic origin of pteridophytes is supported by many workers like "38), (1895, '99, 1924) and others. Bryophytes Lignier (1903), Zimmermann (1930. Campbell at have common features, so it is Dot al improbable that and pteridophytes, in many respects between them. Bryophytic phylogenetic connection and relationship there might _be common morphological and biologic relationship of pteridophytesis based on the following between the two groups similarities existing bryophytes in the gametophytic structure of thallose (a) General similarity vegetative of ferns, Equisetum Anthoceros etc.) and pteridophytes (i.e. prothallus (Riccla, Marchantia, those etc.). development of sex organs, particularly (b) Similarity in the mature structure and of both bryophytes and pteridophytes. of archegonia parasitism of in venter of the archegonium and partial (c)Bncasing of the embryo the in both bryophytes and pteridopbytes. sporophyte upon the gametophyte the young or mature alternation of two life cycle in which there is an (d) Presence of heteromorphic vegetatively unlike generations. between believed that there is phylogenetic connection Bower, Ligoier and Zimmermann archegoniatae type of the latter arose from very primitive tbat bryophytes and pteridophytes, evolutionary lines. Campbell advocated terréstrial plant in two divergent Campbell's idea of bypothetical from anthocerotean type of bryophyte. direct origin from Anthoceros is based on the pteridophytes had from anthocerotean type i.e., direct origin of pteridophytes following facts photo- sporophyte together with highly developed The indefiaite growth of the nearest approach to the entirely (a) sporophyte the t ssue of Anthoceros makes the synthetic of pteridophytes (ferns). independent sporophyte virtue of is independent existence by of Anthoceros capable of leaves and roots (6) The sporophyte it live and can produce 10 grow on earth, can life. bulbous foot-if it is allowed existence of growth and the independent even showing thereby of Psilophyta (a primitive and dichotomously branched shoot The rootless, leafiess to anthocerotean origin of Pteridophyta. (c) bears strong testimony group of pteridopbytes) sporophyte was shifted from regionof an anthocerotean type of and the (d) If the meristematic branching by the meristem then the initiation of dichotomous would have been base to apex formation in the branch apices confinement of sporangia and spore of Anthoceros resemble closel of certain Psilophytales and condition-so possible-such sporophytes an approach to such may, show the beginning of to the distal Anthoceros, therefore, a restriction of spore formation have been found in which there is tissue in the lower portion. sporophytes differentiated into conducting end and in which columella is

H. Economic importance: commonly called Christmas greens, are use as Lycopodlum obscurum, of decoration. Christmas festival and for the purpose garland during in system of of Lycopodium is widely used homoeopathic Generally species oils are the spores of Lycopodium Inundalumn 50% fixed medicine. From is also used in the obtained-such oils are used as cover for pills, this oil are theatrical of fire works. The spores als0 used during per. manufacture the name of Vegetable TOrmance for poducing stage lightening, under Brimstone". The spore dusts of Lycopodium clavalum and other species are in pharmacy as water repellent. Dusting spore-powder on the soft skin usedVes protection. Spore dusts are also used in the preparation of suppositories, De beautiful species of Lycopodiunm volubile i8 very commonly used for table STUDIES IN BOTANY 826 deeoration as it keeps well after collection. Extracts of Lycopodtum plantin stimulant for the past was used as a kidney. Selaginella plant also used during Christmas festival as garland and various type of table decorationor its good conservancy. This plantis greatly regarded with wonder and pleasure for their feathery moss-1like ar Jush-green foliage. S. willdenovii and S. caesia are important for their metallic and different tinge other than tne principal colour, specially bronze and blusih colours. S. serpens is famous for the periodic changes in the colour of its Jeaves, which are in bright green the morning, but slowly become paler during the day and towards night again they regain their beautiful green colour. Hence various species of Selaginella are grown as ornamentals. S. lepidophylla pilifera are as and S. sold curiosities, under the name "resurrection plants." S. botryoides yields a medicine is curing liver diseases. which used in The underground modified stem (corm) of Isoetes, is used as ducks and other aquatic animals. food by The genus Equisetum is of much economically most used for important. The stems of species are polishing floor, furniture etc. clean utensils (alloy wood, and to dishes). Many species of Equisetum acts as weeds in poorly drained soils. The harmful been complete plant of Equisetum arvense has recognised by the German under the which is Pharmacopoeia name of ""Herba Equiseti", used in promoting of this are the discharge urine-the ashes of plant used to relieve acidity and dyspepsia. This silica in active species also contains therapeutically form, for which it has got haemostatic and haemopoietic E. debile a properties. yield medicine which relieves gonorrhoea. Different types of ferns enhances the houses beauty of the garden and and some are also used in the of glass in the button holes of preparation bouquets and in keeping coats. In the tropical tree the building of houses. regions, ferns are used for The stalks and leaves of the plants of are used as Marsilea, Dryopteris, Pteris etc. rhizome of herbage-vegetables, specially during food scarcity. From Dryopteris medicines are The the sporocarps of produced. starchy paste of the Marsilea drummondii is prepared into called "nardoo" by the natives of Australia. cakes, commoly Generally all of types Pteridophyta take part in the formation of coal.