PSILOPHYTALES

PSILOPHYTALES

Psilophytales means naked plants . They are oldest and simplest vascular plants . All the members are fossils . They belong to Devonian period . 

Rhynia 

Rhynia were discovered by Kidston and Lang in Rhynie locality of Aberdeenshire in Scotland . The name Rhynia has been derived from its locality Rhynie . They are found in perfect petrified state .  They grow near volcanoes in habitats saturated with acid water from hot springs . They had subterranean , dichotomously branched rhizome and rootless , leafless shoot . Rhizome bears rhizoids in tuft .  

                  Rhynia major was long and sporophytic phase . Rhynia gwynne-vaughani was short and gametophytic phase . Shoot had protostele . The shoot had adventitious branches ( for vegetative propagation ) and hemispherical projections ( stomata / archegonia , according to Pant ). Sporangium were borne singly or in groups on apices ( difference with psilotales ) . Spores had typical tri-radiate markings . 

Horneophyton ( rootless , leafless ) and asteroxylon ( rootless but with leaves ) were also found along with rhynia at Rhynie in Scotland . 

FUNARIALES

ORDER FUNARIALES 

Funaria 
Plant body consists of rhizoids , axis and leaves . They have multicellular , branched rhizoids with oblique septa . Axis has central conducting strand ( not vascular tissue ) . Leaf is simple , sessile and with midrib . Vegetative reproduction in funaria occurs by fragmentation of primary protonema , secondary protonema , by gemmae , by bulbils and by apospory .
            Funaria is monoecious . Antheridia develop at the apex of main branch and archegonia develop laterally from the male branch . Antheridia and archegonia are intermixed with club shaped paraphysis , perigonial leaves ( in male ) and perichaetial leaves ( in female ) . Funaria have biciliated spirally coiled antherozoids .
            Sporophyte is made up of foot , seta and capsule . Seta is long , slender and twisted . This twisting of seta is characteristic of funaria . The name funaria is derived from latin word funis (= rope) . Capsule has three regions - apophysis ( basal region ) , theca proper and apical region . In apical region , operculum covers the petistome teeth . Annulus connects the operculum with theca proper . Peristome teeth are 2 rings of long curve triangular teeth of cuticle . Each ring has 16 teeth ( 16 + 16 = 32 ) . Teeth of outer ring are thick , large , red and with charateristic transverse thickening bands . Teeth of inner ring are delicate , small and colourless . In theca proper region , air space covers spore sac . Air space is partitioned by green trabeculae . Stoma in funaria are found only in basal apophysis region of sporophyte .
           Archesporium develops from outer layer of endothecium . Entire sporogenous tissue develops in to SMC . Dehiscence of moss capsule takes place by the hygroscopic movements of peristome teeth . Operculum comes out by splitting at annulus . Spores are released in instalments . Spores germinate to form green , filamentous , branched primary protonema , then buds and leafy gametophytes .
       
Polytrichum and pogonatum 
They are similar to funaria . Aerial shoot of pogonatum froms a mat like cushions on moist rocks ,  walls and tree trunks .

SPHAGNALES

SUB CLASS SPHAGNOBRYA
ORDER SPHAGNALES

Sphagnum is an aquatic species . Sphagnum grows in water or marshy land , yet it shows xerophytic characters . But physiologically Sphagnum is hydrophyte . Sphagnum is also called peat moss or bog moss . They produce certain acidic substances which render the medium unsuitable for growth of pathogens . This slows down the decaying process of plant parts . Thus partially decomposed material accumulates at the bottom of water body , year after year .This material is compact , dark and is called peat . Hence the name peat moss is given to these plants .
              Sphagnum has economic importance . It has remarkable water holding capacity , hence it is used in packing live plant parts for transportation . Sphagnum has some antiseptic properties ( used in Word War I ) . Sphagnum has great role in plant succession .
              Gametophyte is differentiated into axis and leaves . Many small branches of limited growth are present at the apex of main axis , form a compact head called coma . Sphagnum has two types of branches - pendent branches ( turn downwards ) and divergent branches ( directed outwards and upwards ) . Leaves are arranged in spiral phyllotaxy on main axis and lateral branches .
              Remarkable water holding capacity of sphagnum is due to retort cells and hyaline cells . Cortex of main axis has bottle or retort cells . They accumulate water . Mature leaves have chlorophyllous cells as well as hyaline cells ( capillary cells ) . Hyaline cells have spiral thickenings and water holding capacity .
              Vegetative reproduction in sphagnum occurs by special branches called innovations . In sphagnum one branch at each node develops more strongly than others , it is called innovations . Antheridia develop on small catkin like branches and archegonia develop on short bud like branches . Sporophyte of Sphagnum is made up of foot , seta and capsule . The foot is bulbous / cylindrical and haustorial in nature . Elongated , leafless axis of archegonial branch , present at the base of sporophyte is called pseudopodium . Pseudopodium elevates the sporophyte . Sphagnum capsule dehisces by explosive air gun mechanism . It is due to pressure developed by air space below the spore sac .
             Since sphagnum shares many features with hepaticopsida , anthocerotopsida and bryopsida , it is regarded as synthetic group .

ANTHOCEROTALES

ORDER ANTHOCEROTALES

Anthoceros 
They occur in moist and shady places . Plant body is dark green , dorsiventral , lobed and prostate thallus . Thallus is without sharply defined midrib .Ventral surface bears always unicellular smooth walled rhizoids along the median line . Scales and tuberculate rhizoids are absent in anthoceros .The chloroplasts contain many pyrenoids ( characteristic feature ) . Thallus has many mucilaginous cavities which are invaded by Nostoc colonies . The presence of endophytic alga Nostoc in anthoceros is not considered a symbiotic association as anthoceros can grow normally even without mucilaginous cavities . Nostoc lives in anthoceros thallus possibly as space parasite . Mucilaginous cavities open on the ventral surface by slime pores.
             The vegetative reproduction in anthoceros occurs by progressive death and decay of thallus , by tubers , by gemmae and by persistant growing apics . Photoperiod generally favours the development of sex organs in anthoceros . Antheridia and archegonia develop endogenously in closed chambers . Antherozoids are elongated , coiled and biflagellate .
              Elongated cylindrical sporangium is characteristic of anthoceros . The sporophyte of anthoceros is made up of capsule and foot ( seta is absent ) . The capsule of anthoceros appears as a long bristle or horn on the dorsal surface of thallus hence the name hornworts has been given to these plants . There is an  intercalary meristematic zone between foot and capsule , which is responsible for indeterminate growth of capsule for long period . Sporophyte shows line of dehiscence . Sporogenous tissue develops from amphithecium . Elaters of anthoceros do not have spiral thickenings , therefore they are called pseudolaters . Pseudolaters are 2-3 celled and branched . Calyptra ( involucre ) is extension of thallus .

JUNGERMANNIALES

JUNGERMANNIALES
1. Plant body is thalloid ( pellia ) or foliose ( porella , frullania ) .
2. Thallus is not differentiated in to photosynthetic and storage region ( unlike to marchantiales ) .
3. Air chambers and air pores are absent ( unlike to marchantiales ) .
4. Elatophores may be present in basal ( pellia ) or apical ( riccardia ) region of capsule .
5. Vegetative reproduction takes place usually by gemmae .
6. Jungermanniales may be anacrogynae = metzgerineae ( apical cell of thallus is not fully utilized in archegonia ) or acrogynae = jungermannineae ( apical cell of thallus is fully utilized in the last  archegonia ) .
7. Archesporium develops from endothecium .
8. Archegonium neck is made up of 5 vertical rows of neck canal cells ( characteristic feature ) .

Pellia 
Plant body is flat , prostate , dorsiventral and dichotomously branched . Thallus is irregularly lobed with sinuous margins . Each lobe is supplied with mid rib . Numerous smooth walled unicellular rhizoids are present along mid rib . They are not up to apical notch . On dorsal side , antheridia are along midrib and archegonia are close to apex of thallus . Antherozoids in pellia are elongated , spirally coiled and biflagellate . Capsule of pellia has spores, elaters ( with spiral thickening ) and basal elatophores ( characteristic feature ) . Elaters have two spiral thickenings .

Porella ( Madotheca ) 
Porella is flat , dorsiventral and foliose . It bears 3 rows of leaves - 2 dorsal ( lateral ) rows and one ventral row of amphigastria . Dorsal leaves are large but amphigastria are small leaves . Dorsal leaves have large antical lobe and small postical lobe .  They also have elaters with spiral thickening .

Frullania
They are similar to porella . Elaters and spore mother cells are arranged in alternate vertical rows in capsule . Capsule splits in 4 halves .

MARCHANTIALES

MARCHANTIALES 
1. Thallus is flat , dorsiventral , dichotomously branched .
2. They have polygonal areas called areoles on dorsal surface of the thallus  .
3. Ventral surface of the thallus bears rhizoids ( smooth walled and tuberculate ) .
4. Scales occur in a single row on the margins of the thallus ( Riccia ) or in 2-4 rows on either side of midrib ( Marchantia ).
5. Internally the thallus is differentiated in to dorsal photosynthetic and ventral storage region .
6. Sex organs are embedded in thallus ( Riccia ) or are stalked  ( Marchantia ) on dorsal surface of the thallus .
7. Antheridia and archegonia develop in antheridial chamber and archegonial chambers resectively . Each chamber has a single sex organ .
8. The neck of archegonium consists of 6 vertical rows of neck canal cells ( characteristic ) .
9. Sporogenous tissue either forms only SMC ( Riccia ) or fertile SMC + sterile elater mother cells ( Marchantia ) .
10. Endothecium behaves as archesporium .
11. Riccia has ligulate scales but Machantia has 2 types of scales - appendiculate and ligulate .

Riccia  
Riccia grow on damp soil , moist and shady places . In terrestrial forms , riccia shows rosette forms . Mid rib is represented by dorsal groove or furrow . Mid rib ends in apical notch . Scales overlap each other in apical region and protect growing points . Scales may be ephemeral or dry according to species . Unbrached photosynthetic filaments are alternate with air channels . Air channels open up by simple air pores on dorsal surface of the thallus . Thallus is narrow , ribbon like and dichotomously branched in aquatic species Riccia fluitans . In Riccia fluitans , air chambers are completely closed by dermal epidermis . Scales and rhizoids are absent R. fluitans .
    Vegetative reproduction in Riccia takes place by death and decay of thallus , by adventitious branches , by tubers and by rhizoids . Sex organs are embedded on dorsal surface . Reproductive structures develop in acropetal succession i.e. olders at posterior and younger at apex . Antherozoids in Riccia are elongated , curved and biflagellate . Neck canal cells and venter canal cells disintegrate to form mucilaginous substance ( rich in proteins , potassium ) . This substance is oozed out to attract antherozoids .
     Riccia shows maximum fertility of sporogenous tissue . But in R. crystallina , some sporogenous cells form nurse cells . They provide nutrition . They are probably forerunners of elaters . Sporophyte is made up of capsule only ( foot and seta are absent ) . Spores are liberated untill the death and decay of thallus .

Marchantia 
Marchantia grows on cool , moist and shady places. M. polymorpha grows as pioneer soil of burnt forest . Scales in Marchantia are of 2 types appendiculate and ligulate . Appendiculate scale has an appendage . Ligulate scales are small and they also retain some water by capillery action in addition to anchorage .       
             Vegetative reproduction in Marchantia occurs by death and decay of thallus , by adventitious branches and gemmae . Many cresecent shaped gemma cups are found along the mid rib on dorsal surface . Gemma cups have fringed margins . They have many small , stalked , multicellular , biconvex gemmae with a notch and many oil cells .
              Sex organs are found on erect branches called gametophores ( antheridiophores and archegoniohores ) from the growing points in apical notches . If antheridia and archegonia are found on same branch , are said androgynophores. Antheridiophore has 8 lobed peltate disc at its apex . Antheridial chambers alternate with air chambers . They borne in acropetal succession . Antherozoids in Marchantia are elongated , curved and biflagellate . The stalk of archegoniophore is slightly longer than that of antheridiophore . They have a peltate disc with 9 rays at its apex . Archegonia too borne in acropetal succession , but after frtilization it undergoes the process of inversion and arrangement reverses from centripetal to centrifugal ( now youngers near centre and olders near periphery ) . Now archegonia are on lower side of peltate disc .
            Sporophyte of Marchantia is enveloped by calyptra , perigynium and perichaetium ( outward ).

BRYOPHYTES

BRYOPHYTES 
Bryophyte means moss plant . They are regarded as amphibian of plant kingdom because they have terrestrial species as well as aquatic species . Dendroceros grow as epiphytes . Buxbaumia aphylla is saprophyte .

General characters 
1. Gametophytic phase is dominant .
2. Plant body is made up of rhizoids ( not roots like pteridohytes ) , stem and leaves .
3. They lack vascular tissue ( unlike pteridophytes ) .
4. Sexual reproduction is oogamous type .
5. Sex organs are multicellular and with outer one celled thick sterile jacket ( characteristic feature ) .
6. Water is necessary for fertilization ( like algae ) .
7. Zygote does not has any resting period ( unlike algae ) , they immediately divide to form embryo ( not spores like algae ) after fertilization .
8. Embryo develops within archegonium .
9. Anthocerotales plastids are with pyrenoids ( like algae ) .
10 . Green moss protonema resembles filametous green algae .
11. Rhizoids absorp water , minerals and fix the plant to the substratum .

Origin of bryophytes
Anthoceros , sphagnum etc show resemblance with pteridophytes and green protonema in mosses resemble filamentous green algae .

Classification of bryophytes 
Term bryophyta was coined by Braun . Prof. Shiv ram kashyap is father of Indian bryology . His book is Liverworts of western himalalayas and the Punjab plains . Prof. S K pandey of Rae Bareli and Prof. Ram Udar of Basti are also famous .
     Bryophyta is divided in to 3 classes -
1. Hepaticopsida = Hepaticae = Liverworts -
Plant body is thalloid or foliose . Thalloid plant bodies are prostate , lobed and dichotomously branched . Archesporium develops from endothecium . Some imp orders are Marchantiales , jungermanniales .
2. Anthocerotopsida = Anthocerotae = Hornworts - Plant body is flat , dorsiventral and thalloid . Tuberculate rhizoids and scales are absent . Intercellular mucilage cavities open up on ventral surface  by slit like slime pores . Sex organs are embedded on dorsal surface of the thallus . Sporogenous tissue develops from amphithicium . Elaters do not have thickening bands and are called pseudolaters . Imp order is anthocerotales .
3. Bryopsida =Musci = Mosses - Gametophyte has 2 growth stages - protonema stage and leafy gametophyte stage . Some imp sub-classes are sphagnobrya ( order sphagniales ) , eubrya or brydae ( order funariales ) . Bryidae ( Eubrya ) is the most highly evolved group of bryophyte and are called true mosses . Operculum and peristomial teeth are characteristics of brydae ( eybrya ) .