Archegonium and its formation are properly exposed and neck is formed of six rows of cell in bryophytes; Partially embedded archegonium and its neck have only four rows of cells in pteridophytes.
Antheridium is stalked kind of bryophytes; In pteridophytes sessile kind of antheridium. Bryophytes are homosporous, whereas pteridophytes can be homosporous or heterosporous. In bryophytes, the gametophyte is dominating whereas saprophytes are dominating in pteridophytes.
Examples include mosses, liverworts, hornworts of bryophytes while spikemosses, clubmosses, ferns, quillworts are examples of pteridophytes. Gametophytes of bryophytes are always autotrophic and macroscopic; while in pteridophytes, gametophytes are saprophytic or extremely reduced microscopic structures.
Similarities Both have the heteromorphic alternation of generations. Multicellular sporangia. The main plant body is sporophytic which forms a dominant phase in the life cycle. The gametophytic generation bears male and female sex organs viz. The antherozoids male gamates produced in large numbers are motile, while the eggs female gametes are non-motile and are borne singly in archegonia. Fusion between an egg and an antherozoid results in the formation of a diploid 2n zygote.
In homosporous member, spores germinate to produce monoecious i. In this case, the sex determination takes place at the time of formation of antheridium and archegonium Fig. In heterosporous member, micro- and mega- spores, on germination, produce male and female gametophytes, respectively i.
Life Cycle of Pteridophytes: The alternation of sporophyte 2n and gametophyte n generations in the life cycle is normally coordinated with a periodic doubling because of syngamy followed by a halving because of meiosis of the chromosome number. In some ferns, the embryo develops from an unfertilised egg, a phenomenon termed as parthenogenesis i. A third deviation from the usual life cycle of pteridophyte is the phenomenon of apogamy. The presence of true roots, stem, leaves and vascular tissues thus have distinguished them from the preceding group i.
The pteridophytes resemble the Spermatophyta in having well- developed vascular tissues but differ from them in lacking flowers, fruits or seeds. Stelar System in Pteridophytes: The name stele has been derived from the Greek word stele meaning column or pillar or set or stand. According to them the fundamental parts of a shoot are the cortex and the stele a central cylinder where the endodermis is the anatomical boundary between these two fundamental units.
In lycopsids, like Lycopodium and Selaginella, the stele of the axis and the leaf traces develop independently. The leaf traces are very small and superficially connected to the vascular cylinder of the stem Fig.
But in ferns e. It is considered as a composite structure consisting of both cauline stem and foliar leaf vascular components. Protostele: It is characterised by the absence of central column of pith. Thus it is a non-meduMated stele, in its most simplest form it is merely composed of a central strand of primary xylem surrounded by a cylinder of phloem. From the phylogenetic as well as ontogenic standpoint the most primitive type of stele is the protostele. All other types of steles have been derived from it in the course of evolution.
Protosteles are found in primitive psilophytes like Rhynia, Horneophyton and also in many living primitive vascular plants e. The phloem, instead of forming a continuous ring, is situated in the form of small groups in between the radiating arms of the xylem e.
It is considered as an advancement in anatomical development over protostele. The siphonostele and its variations are found frequently in the sphenopsids and ferns.
Depending upon the presence or absence of leaf trace and branch trace, Jeffery divided siphonostele into two groups: i Cladosiphonic: It is characterised by the absence of leaf traces e. The solenostele may be ectophloic Fig. It is usually found in ferns where rhizome is very small and crowded with leaves e.
A dictyostele has many scattered vascular strands. All the meristeles are surrounded by a common endodermis. Polycyclic stele may be of two types: i. Economic Importance of Pteridophytes: The economic importance of pteridophytes is not well-documented, because due attention has not been given towards their use in human welfare. However, there are many reports on their uses, specially as food plants, medicinal plants and horticultural plants.
Pteridophytes Used as Food: The young leaf tips of ferns, the circinate ptyxis or the chroziers are used as vegetable. The croziers of Matteuccia struthiopters as canned or frozen are served as spring vegetable in USA and Canada. The rhizome of many ferns such as Pteris, rich in starch, is used as food. The corm modified stem of Isoetes is used as food by pigs, ducks and other animals. Pteridophytes Used as Fodder: Dry fronds of many ferns form the livestock for catties.
The quadrifid lamina of Marsilea resembles a clover Trifolium has been used as fodder for animals as a substitute for clover.
The foliages of Lycopodium are used as tincture, powder, ointment and cream as a stomachic and diuretic. Equisetum is rich in silicic acid and silicates. Potassium, aluminium and manganese, along with fifteen types of flavonoid compounds, have been reported from Equisetum. The flavonoids and saponins are assumed to cause the diuretic effect.
The silicon is believed to exert connective tissue-strengthening and anti-arthritic action. Several ferns have been used as herbal medicine. The decoction of Asplenium is used for cough and a good hair wash. The expectorant of Polypodium is used as a mild laxative, while the tonic is used for dyspepsia, loss of appetite and hepatic problem. The ointment made from its root is used for application to wound.
The rhizome and frond bases of Dryopteris have been used to determine the origin and pathways of dispersed pathogenic insects like corn ear- worm. Pteridophytes Used as Horticultural Plants: Many species of pteridophytes are cultivated for their aesthetic value. Several species of Selaginella are used as a ground cover in an undisturbed area because of their decent foliage and colour.
The stages in progressive evolution of sori can be depicted as follows: 1 simple clusters of sporangia, these more or less coalesced family Marattiaceae or separate Gleicheniaceae , all of them maturing at the same time, 2 gradate clusters of sporangia, the outermost ones maturing first, the innermost last, and 3 mixed clusters of sporangia, all ages present, the younger ones arising from the same meristematic zones as the older ones.
The adaptive significance of this change is probably related to the duration of spore production, the mixed character of the more advanced sori extending the period beyond that of solitary sporangia or of simple, simultaneously maturing sori. Sporangia and especially sori have traditionally provided the most important characters for fern classification. Indeed, many unrelated ferns were once classified together because of what are now believed to have been coincidental convergences in soral structure.
Between one-half and two-thirds of the species of ferns have one or another of the following six soral arrangements: 1 A linear arrangement of sporangia along veins, avoiding the leaf area between the veins, is found in many fern genera, especially in the genus Pityrogramma.
Such sori probably arose by the fusion of smaller clusters of sori. Of the many arrangements of indusiate sori i. The indusium Protection of the sporangial cluster from exposure, drying, and other hazards is accomplished in various ways, such as by the formation of the sori in grooves or pockets or by the production of various forms of covers.
Pteridophytes also show a transition from simple to complex leaves. Some pteridophyte groups, including the club mosses and horsetails classes Lycopodiopsida and Equisetopsida , have simple microphyllous leaves, featuring a single, unbranched vein and modest vascular supplies that do not cause breaks or gaps in the stem vasculature.
The true ferns class Filicopsida , however, have larger, more complex macrophyllous leaves whose veins are usually extensively branched, placing such large demands on the plant's vasculature that distinctive gaps form in the xylem and phloem of the stem. 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.
Ferns can be used to illustrate the life cycle stages common to all pteridophytes. Diploid 2n fern sporophytes are familiar to most people and are often found as quiet accompaniments in floral arrangements. When mature, the undersides of fern leaves produce clusters of capsular structures called sporangia, within which meiosis forms the haploid n spores.
These spores are released from the sporangia, often when dry wind currents cause the active snapping of the capsules, lofting the spores into the air.Saprophytic phase is an independent autotrophic. As their gametophytic generation is dominating, they produce gametes. But they fail to produce flowers or seeds.
They are the earliest known vascular plants which originated in the Silurian period million years ago of Palaeozoic Era and subsequently diversified and formed the dominant vegetation on earth during Devonian to Permian period. The roots and stems of Osmunda are used to make beds for growing orchids. In homosporous member, spores germinate to produce monoecious i. Although most pteridophytes are homosporous produce spores that are all the same size , a few groups are heterosporous with large megaspores and small microspores. Antheridium: i.
The gametophytic generation bears male and female sex organs viz. The evidences in support of the above view are: a Coleochaete is a soil alga in the order Coleochaetales, subfamily Charophyceae, which produces a small vegetative thallus as the major, haploid part of its life cycle. Life Cycle 8.
In some ferns, the embryo develops from an unfertilised egg, a phenomenon termed as parthenogenesis i.
Economic Importance of Pteridophytes: The economic importance of pteridophytes is not well-documented, because due attention has not been given towards their use in human welfare. Water boiled with Lycopodium clavatum is used for dyeing the woollen clothes which becomes blue when dipped in a bath of Brazil wood. They had acquired certain characteristic features in the early geologic period that helped them to make their successful adaptation on land. Thus it is a non-meduMated stele, in its most simplest form it is merely composed of a central strand of primary xylem surrounded by a cylinder of phloem.
Bryophytes are homosporous, whereas pteridophytes can be homosporous or heterosporous. The diploid zygotes , produced by the fusion of haploid egg and sperm, divide mitotically and differentiate into mature sporophytes, completing the life cycle. Similarly, Asplenium adulterinum is an indicator of nickel and Actinopteris australis is a cobalt indicator plant. Microspores, after germination, produce male gametophyte, while megaspores produce female gametophyte.
Presence of multicellular sex organs i. Spores that are wind-borne to shady, moist habitats germinate and yield multicellular, but microscopic, gametophytes, the sexual stage of the life cycle. The leaves and stems, in most of the cases, are provided with filiform trichomes. Bryophytic Origin: Many hypotheses have been put forward in support of bryophytic origin of pteridophytes, although there is no unanimity regarding the ancestral stock as well as the mode of origin. But in ferns e.