Chapter 29
Chapter 29
PLANT DIVERSITY I:
PLANT DIVERSITY I:
HOW PLANTS COLONIZED LAND
HOW PLANTS COLONIZED LAND
There are about 290,000 of land plants on Earth. There are about 290,000 of land plants on Earth.
LAND PLANTS EVOLVED FROM GREEN ALGAE LAND PLANTS EVOLVED FROM GREEN ALGAE
Charophycean ance!or Charophycean ance!or
Charophyceans are the green algae most closely related to land plants. Charophyceans are the green algae most closely related to land plants.
Land plants probably are probably derived from a group of green algae called
Land plants probably are probably derived from a group of green algae called charophy!echarophy!e..
Land plants share with the charophyceans the following traits Land plants share with the charophyceans the following traits
!.
!. Roe!!e ce""#"oe$yn!he%&%n' co(p"e)eRoe!!e ce""#"oe$yn!he%&%n' co(p"e)e land plants and charophyceans posses a land plants and charophyceans posses a rosette"shape array of proteins that synthesi#e cellulose microfibrils in their cell wall. rosette"shape array of proteins that synthesi#e cellulose microfibrils in their cell wall.
$ther cellulose wall"containing algae %e. g. brown algae, dinoflagellates&, have linear arrays $ther cellulose wall"containing algae %e. g. brown algae, dinoflagellates&, have linear arrays of cellulose"producing proteins.
of cellulose"producing proteins.
This suggests a common ancestor between the charophytes and land plants. This rosette This suggests a common ancestor between the charophytes and land plants. This rosette synthesi#ing system evolved independently of the cellulose ma'ing system of other green synthesi#ing system evolved independently of the cellulose ma'ing system of other green algae.
algae.
2.
2. Pero)%o(e en&y(ePero)%o(e en&y(e the charophyceans and land plants have the charophyceans and land plants have en&y(e %n !he%ren&y(e %n !he%r pero)%o(e
pero)%o(e that minimi#e the loss of carbohydrate due to photorespiration. that minimi#e the loss of carbohydrate due to photorespiration.
$ther alga groups do not have these en#ymes in their pero(isomes. $ther alga groups do not have these en#ymes in their pero(isomes.
).
). S!r#c!#re o* !he S!r#c!#re o* !he *"a'e""a!e per(*"a'e""a!e per( details of the sperm of charophyceans resemble those details of the sperm of charophyceans resemble those of land plants that have flagellated sperms.
of land plants that have flagellated sperms.
*.
*. Ce"" p"a!e *or(a!%on +#r%n' cy!o,%ne%Ce"" p"a!e *or(a!%on +#r%n' cy!o,%ne% cell division features a comple( networ' of cell division features a comple( networ' of microtubules and +olgi vesicles, the
microtubules and +olgi vesicles, the phra'(op"a!phra'(op"a!, again as found in all land plants., again as found in all land plants.
.
. DNA an+ RNA e-#enceDNA an+ RNA e-#ence support their close relation to the charophytes, especially Chara support their close relation to the charophytes, especially Chara and Coleochaete.
and Coleochaete.
TERRESTRIAL ADAPTATION OF LAND PLANTS TERRESTRIAL ADAPTATION OF LAND PLANTS
ADAPTATIONS ENA.LING THE MOVE TO LAND ADAPTATIONS ENA.LING THE MOVE TO LAND
-
- layer oflayer of poropo""en%nporopo""en%n protects charophytes from desiccation sporopollenin is found in the protects charophytes from desiccation sporopollenin is found in the spore wall of land plants.
spore wall of land plants.
/anger of desiccation reuired new adaptations transport tissue, cuticle, etc. /anger of desiccation reuired new adaptations transport tissue, cuticle, etc.
1upport against gravity. 1upport against gravity.
lants are eu'aryotic, multicellular, mostly autotrophic organisms, with haploid"diploid life lants are eu'aryotic, multicellular, mostly autotrophic organisms, with haploid"diploid life cycles, which retain embryo within female se( organ on parent plant the cell wall contains cycles, which retain embryo within female se( organ on parent plant the cell wall contains cellulose.
cellulose.
1cientists are studying the ultrastructure of cells, analy#ing macromolecules and comparing 1cientists are studying the ultrastructure of cells, analy#ing macromolecules and comparing morphology with life cycles.
morphology with life cycles.
There are several proposals to rearrange the boundaries of the 'ingdom lantae There are several proposals to rearrange the boundaries of the 'ingdom lantae
•
• $nly the Embryophytes the present and traditional system.$nly the Embryophytes the present and traditional system. •
• E(pand it to include the charophyceans 3ingdom 1treptophyta.E(pand it to include the charophyceans 3ingdom 1treptophyta. •
• E(pand it further to include all the green algae, Chlorophyta 3ingdom 4iridiplantae.E(pand it further to include all the green algae, Chlorophyta 3ingdom 4iridiplantae.
DERIVED TRAITS OF PLANTS DERIVED TRAITS OF PLANTS
The following characteristics are common to all four groups of land plants but are absent in the The following characteristics are common to all four groups of land plants but are absent in the charophyceans.
charophyceans.
!.
!. Ap%ca" (er%!e(Ap%ca" (er%!e( cluster of embryonic cells found at the tip of shoots and roots. cluster of embryonic cells found at the tip of shoots and roots.
2.
2. A"!erna!%on o* A"!erna!%on o* 'enera!%o'enera!%onn a characteristic life cycle. a characteristic life cycle.
-lternatio
-lternation of genn of generation doeration does not oes not occur in the ccur in the charophycharophyceans. Thceans. This suggeis suggests thatsts that
alternation of generation arose independently in land plants. - life cycle characteri#ed by a alternation of generation arose independently in land plants. - life cycle characteri#ed by a multicellular
multicellular hap"o%+ 'a(e!ophy!e !a'ehap"o%+ 'a(e!ophy!e !a'e followed by a followed by a multicellumulticellularlar +%p"o%+ porophy!e+%p"o%+ porophy!e !a'e
!a'e..
M#"!%ce""#"ar/ +epen+en! e(0ryo:
M#"!%ce""#"ar/ +epen+en! e(0ryo: The The &y'o!e&y'o!e is retained surrounded by tissues of the is retained surrounded by tissues of the gametophyte. The parental tissue provides the embryo with nutrients.
gametophyte. The parental tissue provides the embryo with nutrients. P"acen!a" !ran*erP"acen!a" !ran*er ce""
ce"" present in the embryo and sometimes in the gametophyte as well, enhance the present in the embryo and sometimes in the gametophyte as well, enhance the transfer of nutrients.
transfer of nutrients.
).
). Spore pro+#ce+ %n poran'%aSpore pro+#ce+ %n poran'%a haploid reproductive cells that become a multicellular haploid reproductive cells that become a multicellular haploid gametophyte by mitosis.
haploid gametophyte by mitosis.
The multicellular sporangium contains sporocytes, the cells that undergo meiosis to form The multicellular sporangium contains sporocytes, the cells that undergo meiosis to form spores.
spores.
Sporopo""en%n
Sporopo""en%n , the most durable organic material 'nown, ma'es the walls of the spores., the most durable organic material 'nown, ma'es the walls of the spores.
*.
*. M#"!%ce""#"ar 'a(e!an'%aM#"!%ce""#"ar 'a(e!an'%a the gametes of land plants are produced in multicellular organs the gametes of land plants are produced in multicellular organs called gametangia. -lgae produce their gametes in unicellular gametangia, inside a single called gametangia. -lgae produce their gametes in unicellular gametangia, inside a single cell.
cell.
A+ap!a!%on *or 1a!er !ranpor! an+ coner2a!%on3 A+ap!a!%on *or 1a!er !ranpor! an+ coner2a!%on3
43
5
533 SS!!oo((aa!!aa %sing. %sing. !o(a!o(a& for gas e(change and control of transpiration.& for gas e(change and control of transpiration.
63
63 Transport system orTransport system or 2ac#"ar !%#e2ac#"ar !%#e
Secon+ary (e!a0o"%c co(po#n+ Secon+ary (e!a0o"%c co(po#n+
Land plants ma'e many metabolic compounds that are produced by side branches off the Land plants ma'e many metabolic compounds that are produced by side branches off the primary metabolic pathways that ma'e lipids, carbohydrates, proteins and other compounds primary metabolic pathways that ma'e lipids, carbohydrates, proteins and other compounds common to all organisms.
common to all organisms.
Cell wall
Cell wall containscontains "%'n%n"%'n%n, a polymer, to strengthen and support upright structures., a polymer, to strengthen and support upright structures.
$ther secondary compounds are al'aloids, tannins, and phenolics %flavonoids&. $ther secondary compounds are al'aloids, tannins, and phenolics %flavonoids&.
These compounds functions as a protection against herbivores, absorb harmful 64 radiation, These compounds functions as a protection against herbivores, absorb harmful 64 radiation, and are involved in the symbiotic relationship with soil microbes.
and are involved in the symbiotic relationship with soil microbes.
ORIGIN OF LAND PLANTS ORIGIN OF LAND PLANTS
-bout *
-bout *7 million y7 million years ago, ears ago, in the midin the mid"$rdovician"$rdovician, plants w, plants were widesere widespread all ovpread all over the woer the worldrld as shown by the many spores found in sediments of this period.
as shown by the many spores found in sediments of this period.
8n a relatively short time of about 0 million years, plant diversified abundantly and coloni#ed 8n a relatively short time of about 0 million years, plant diversified abundantly and coloni#ed many land areas.
many land areas.
There are four main groups of land plants There are four main groups of land plants
•
• ryophytes, including mosses.ryophytes, including mosses. •
• teridophytes, including ferns and seedless vascular plants.teridophytes, including ferns and seedless vascular plants. •
• +ymnosperms, including conifers.+ymnosperms, including conifers. •
• -ngiosp -ngiosperms includerms including flowerining flowering plants.g plants.
Land plants are distinguished from algae by the production of multicellular embryos that remain Land plants are distinguished from algae by the production of multicellular embryos that remain attached to the mother plant, which protects and nourishes the embryos.
attached to the mother plant, which protects and nourishes the embryos.
ryophytes are distinguished from the other three groups of land plants by the lac' of a vascular ryophytes are distinguished from the other three groups of land plants by the lac' of a vascular tissue made of special cells called (ylem and phloem. 1ome bryophytes have water and nutrient tissue made of special cells called (ylem and phloem. 1ome bryophytes have water and nutrient transport system made of a different 'ind of cells.
transport system made of a different 'ind of cells.
•
• TheThe 2ac#"ar y!e(2ac#"ar y!e( transports water and nutrients. transports water and nutrients.
teridophytes do not produce seeds. +ymnosperms and angiosperms produce seeds. teridophytes do not produce seeds. +ymnosperms and angiosperms produce seeds.
-
- seed conseed consists of a sists of a plant embplant embryo with a fryo with a food storinood storing tissue ag tissue and a surnd a surrounding rounding coat forcoat for protection.
•
• The first vascular plants to produce seeds evolved about ):0 million years ago.The first vascular plants to produce seeds evolved about ):0 million years ago. •
• Their seeds were not enclosed in any speciali#ed chamber.Their seeds were not enclosed in any speciali#ed chamber.
-ngiosp
-ngiosperms producerms produce flowers ae flowers and conifend conifers produce rs produce ;cones;, a ;cones;, a speciali#especiali#ed reproducd reproductivetive structure.
structure.
•
• -ngiosp -ngiosperms producerms produce their seee their seeds in speds in speciali#ed chaciali#ed chambers calmbers called ovariesled ovaries.. •
• +ymnosperms do not produce seed in ovaries.+ymnosperms do not produce seed in ovaries.
The word
The word 'ra+e'ra+e is used to designate a collection of organisms that shate a common level of is used to designate a collection of organisms that shate a common level of biologial organi#ation or adaptation.
biologial organi#ation or adaptation.
.RYOPHYTES .RYOPHYTES
-bout !
-bout !7,000 sp7,000 species woecies worldwide dividrldwide divided into threed into three /ivisione /ivisions or phylas or phyla .ryophy!a.ryophy!a, the mosses, the mosses Hepa!ophy!a
Hepa!ophy!a, the liverworts and, the liverworts and An!hocerophy!aAn!hocerophy!a, the hornworts., the hornworts.
Their life cycle is similar but the three groups may not be closely related. The bryophytes may Their life cycle is similar but the three groups may not be closely related. The bryophytes may form a polyphyletic group.
form a polyphyletic group.
ryophyt
ryophytaa refers to the phylum of mosses only bryophyt refers to the phylum of mosses only bryophyt ee refer to the three phyla mentioned refer to the three phyla mentioned above.
above.
Charac!er%!%c o* !he 0ryophy!e Charac!er%!%c o* !he 0ryophy!e
!.
!. 1mall plan1mall plants found in ts found in moist enviromoist environments, lanments, lac' woody tc' woody tissue and issue and usually fousually form mats sprearm mats spreadd over the ground.
over the ground.
2.
2. +ametoph+ametophyte genyte generation ieration is dominas dominant sporont sporophyte iphyte is parasitic s parasitic on the on the gametophygametophyte.te.
).
). ryophyryophytes have cutes have cuticle, stomaticle, stomata and muta and multicellular galticellular gametangia metangia that allow that allow them to suthem to survive onrvive on land.
land.
*.
*. ryophyryophytes need tes need water to water to reproduce reproduce and moand most specst species lac' vies lac' vascular tiascular tissue %(yssue %(ylem andlem and phloem&.
phloem&.
.
. 5ater 5ater transport transport is mostly this mostly through caprough capillary actionillary action, diffus, diffusion and cyion and cytoplasmic stretoplasmic streaming. Thaming. Theyey lac' true roots, stems and leaves.
lac' true roots, stems and leaves.
The gametophyte of mosses is a one"cell"thic' filament 'nown as the protonema that eventually The gametophyte of mosses is a one"cell"thic' filament 'nown as the protonema that eventually produces buds having meristematic tissue. These meristems produce an upright structure called produces buds having meristematic tissue. These meristems produce an upright structure called the
the 'a(e!ophore'a(e!ophore..
These gametophytes are one to a few cells thic' and obtain nutrients and water by direct These gametophytes are one to a few cells thic' and obtain nutrients and water by direct absorption from the environment.
<ost mosses do not have conducting tissue. 1ome species have speciali#ed cells that conduct <ost mosses do not have conducting tissue. 1ome species have speciali#ed cells that conduct water and nutrients but lac' lignin in their cell walls.
water and nutrients but lac' lignin in their cell walls.
The gametophores are anchored by fragile
The gametophores are anchored by fragile rh%&o%+rh%&o%+. =hi#oids are either single elongated cells. =hi#oids are either single elongated cells as those found in liverworts and hornworts, or filaments of cells as those of mosses.
as those found in liverworts and hornworts, or filaments of cells as those of mosses.
=hi#oids are not made of tissues and do not absorb any significant amount of water. 8n that way =hi#oids are not made of tissues and do not absorb any significant amount of water. 8n that way they differ from roots.
they differ from roots.
ryophytes have smallest and simplest sporophyte of any group. ryophytes have smallest and simplest sporophyte of any group.
The sporophyte remains attached to the gametophyte throughout its lifetime, dependent of the The sporophyte remains attached to the gametophyte throughout its lifetime, dependent of the gametophyte for food, water and minerals.
gametophyte for food, water and minerals.
The mature sporophyte of mosses consists of a
The mature sporophyte of mosses consists of a *oo!*oo! embedded in the archegonium, a embedded in the archegonium, a e!ae!a or or stal' is present in the phylum ryophyta, and a
stal' is present in the phylum ryophyta, and a cap#"ecap#"e or sporangium. The cap or or sporangium. The cap or ca"yp!raca"yp!ra closes the
closes the per%!o(eper%!o(e or opening or the capsule. or opening or the capsule.
THE ORIGIN OF VASC7LAR PLANTS THE ORIGIN OF VASC7LAR PLANTS..
>erns and other seedless vascular plants formed the first forests. >erns and other seedless vascular plants formed the first forests.
!.
!. The ne(The ne(t step in lat step in land plant end plant evolution ivolution included thncluded the devee development of lopment of an indean independentpendent sporophyte.
sporophyte.
•
• -t first thi -t first this sporophys sporophyte was of ete was of eual si#e ual si#e as the gaas the gametophymetophyte.te. •
• Coo'sonia caledonica, from the 1ilurian %?*20 million years ago& roc's of Europe andCoo'sonia caledonica, from the 1ilurian %?*20 million years ago& roc's of Europe and
@orth -merica, is the oldest 'nown land plant. @orth -merica, is the oldest 'nown land plant.
•
• 1mall, leafless, rootless, dichotomous a(es with terminal sporangia.1mall, leafless, rootless, dichotomous a(es with terminal sporangia.
2.
2. TrTranansposport in (rt in (ylylem anem and phd phloeloem.m.
•
• Ph"oe( for the transport of dissolved carbohydrates.Ph"oe( for the transport of dissolved carbohydrates. •
• 8y"e( for water and mineral transport.8y"e( for water and mineral transport. •
• L%'n%nL%'n%n strengthens the vascular tissue cells. strengthens the vascular tissue cells.
).
). EvEvololututioion on of rf rooootsts..
•
• =oots anchor plants and allow the absorption of water and nutrients from the soil.=oots anchor plants and allow the absorption of water and nutrients from the soil. •
• =oot tissues of living plants closely resemble stem tissues of early vascular plants=oot tissues of living plants closely resemble stem tissues of early vascular plants
preserved in fossils. preserved in fossils.
•
• =oots may have evolved from the lowest subterranean parts of the stem.=oots may have evolved from the lowest subterranean parts of the stem. •
• The oldest lycophyte fossil had simple roots *00 million years ago.The oldest lycophyte fossil had simple roots *00 million years ago.
*.
•
• M%crophy""M%crophy"" are single veined leaves associated and evolved as superficial are single veined leaves associated and evolved as superficial
outgrowth of the stem. outgrowth of the stem.
•
• M%crophy""M%crophy"" first appear in the fossil recorda about *!0 million years ago.first appear in the fossil recorda about *!0 million years ago. •
• Me'aphy""Me'aphy"" have a comple( venation pattern, and evolved from a branch system. have a comple( venation pattern, and evolved from a branch system. •
• Me'aphy""Me'aphy"" appeared about )70 million years ago, at the end of the /evonian. appeared about )70 million years ago, at the end of the /evonian.
.
. The spThe sporoporophyte bhyte becamecame the dome the dominaninant genet generatioration.n.
Sporophy""
Sporophy"" are modified leaves that bear spores. are modified leaves that bear spores.
1porophylls may be grouped into cone"li'e structures called
1porophylls may be grouped into cone"li'e structures called !ro0%"%!ro0%"% %sing. %sing. strobilus&.strobilus&.
•
• Ho(opory production of one 'ind of spores.Ho(opory production of one 'ind of spores.
-- 1pores produce a bise(ual gametophyte that produces eggs and sperms.1pores produce a bise(ual gametophyte that produces eggs and sperms.
•
• He!eropory production of two 'inds of spores.He!eropory production of two 'inds of spores.
-- AaploidAaploid (e'apore(e'apore develop into a female gametophyte. develop into a female gametophyte.
-- AaploidAaploid (%cropore(%cropore develop into a male gametophyte. develop into a male gametophyte.
CLASSIFICATION OF SEEDLESS VASC7LAR PLANTS CLASSIFICATION OF SEEDLESS VASC7LAR PLANTS
There are two phyla of pteridophytes found in the modern flora
There are two phyla of pteridophytes found in the modern flora L%cophy!aL%cophy!a and and P!erophy!aP!erophy!a..
43 Phy"#( Lycophy!a 43 Phy"#( Lycophy!a..
There are about ! genera of lycophytes and appro(imately !000 living species. There are about ! genera of lycophytes and appro(imately !000 living species.
This phylum includes the Lycopods %club mosses&, 1elaginella %spi'e moss& and 8soetes This phylum includes the Lycopods %club mosses&, 1elaginella %spi'e moss& and 8soetes %uillwort&.
%uillwort&.
This evolutionary line e(tends bac' into the /evonian %*09"):) mya& but were most prevalent in This evolutionary line e(tends bac' into the /evonian %*09"):) mya& but were most prevalent in the wet swamps of the Carboniferous period %):)"290 mya&.
the wet swamps of the Carboniferous period %):)"290 mya&.
They eventually split up into two evolutionary lines. They eventually split up into two evolutionary lines.
•
• The first were very large woody trees that did not survive in the drier climate at the endThe first were very large woody trees that did not survive in the drier climate at the end
of and after the Carboniferous age. 8n the Carboniferous some lycophytes were forest" of and after the Carboniferous age. 8n the Carboniferous some lycophytes were forest" forming trees more than ) meters tall.
forming trees more than ) meters tall.
•
• The second and the surviving group of Lycopods are the small and herbaceous trees.The second and the surviving group of Lycopods are the small and herbaceous trees.
Lycophyta remains became the largest coal deposits of all geologic time. Lycophyta remains became the largest coal deposits of all geologic time.
The sporophytes of lycophytes consist of true roots, stems and leaves %microphylls&. The sporophytes of lycophytes consist of true roots, stems and leaves %microphylls&.
1ome 1elaginella are
Sporophy""
Sporophy"" are speciali#ed leaves that bear sporangia and are organi#ed into a structure are speciali#ed leaves that bear sporangia and are organi#ed into a structure called the
called the !ro0%"#!ro0%"# %pl. strobili&. %pl. strobili&.
53 Phy"#( P!erophy!a 53 Phy"#( P!erophy!a
P%"ophy!e 91h%, *ern P%"ophy!e 91h%, *ern
8t includes two living genera, silotum and Tmesipteris, from tropical and subtropical regions of 8t includes two living genera, silotum and Tmesipteris, from tropical and subtropical regions of the world...
the world...
•
• 1porophyte with a dichotomously branching aerial and subterranean stem system.1porophyte with a dichotomously branching aerial and subterranean stem system. •
• True roots lac'ing.True roots lac'ing. •
• 6nderground stems with rhi#oids and with a fungal association.6nderground stems with rhi#oids and with a fungal association. •
• -erial stems lac'ing le -erial stems lac'ing leaves but waves but with scale"li'e ith scale"li'e or larger leor larger leaf"li'e strucaf"li'e structures %enatures %enations&tions&
6ntil recently they were placed in a phylum of their own, but /@- seuences analysis and 6ntil recently they were placed in a phylum of their own, but /@- seuences analysis and sperm ultrastructure study has shown that they are related to present day fern.
sperm ultrastructure study has shown that they are related to present day fern.
The lac' of roots and leaves may be due to simplification, a derived or secondary characteristic, The lac' of roots and leaves may be due to simplification, a derived or secondary characteristic, rather than a maintained characteristic from ancient ancestors, a primitive characteristic.
rather than a maintained characteristic from ancient ancestors, a primitive characteristic.
Sphenophy!e 9Hore!a%" Sphenophy!e 9Hore!a%"
1phenopsids e(tend bac' to the /evonian %*09"):) mya& and reached their ma(imum 1phenopsids e(tend bac' to the /evonian %*09"):) mya& and reached their ma(imum development in the Carboniferous %):)"290 mya.&
development in the Carboniferous %):)"290 mya.&
-
- family of ofamily of one e(tane e(tant genusnt genus, Euisetu, Euisetum %ca. ! spm %ca. ! species&, of ecies&, of nearly wnearly worldwide distorldwide distribution inribution in damp habitats such as riverban's, la'eshores, and marshes. <ichigan is a center of diversity damp habitats such as riverban's, la'eshores, and marshes. <ichigan is a center of diversity for the genus with nine native species.
for the genus with nine native species.
•
• The sporophyte of Euisetum is differentiated into an underground rhi#ome that bearsThe sporophyte of Euisetum is differentiated into an underground rhi#ome that bears
adventitious roots and an upright, photosynthetic stem with whorls of microphylls... adventitious roots and an upright, photosynthetic stem with whorls of microphylls...
•
• Tough perennial herbs with Bointed, ridged aerial stems with distinct nodes.Tough perennial herbs with Bointed, ridged aerial stems with distinct nodes.
•
• 1tems rough, accumulating silica and metals, and comple( anatomically.1tems rough, accumulating silica and metals, and comple( anatomically.
•
• The aerial stems contain a large central pith region, which in mature plants is hollow.The aerial stems contain a large central pith region, which in mature plants is hollow.
•
• 1urrounding the pith cavity are discrete bundles of vascular tissue this arrangement of1urrounding the pith cavity are discrete bundles of vascular tissue this arrangement of
conducting tissue is 'nown as a eustele. conducting tissue is 'nown as a eustele.
=ecent molecular data suggest that they are closely related to ferns and should be classified =ecent molecular data suggest that they are closely related to ferns and should be classified with them.
with them.
Fern Fern
The fossil record of ferns e(tends bac' into the Carboniferous %):)"290 mya& but their origins is The fossil record of ferns e(tends bac' into the Carboniferous %):)"290 mya& but their origins is in the /evonian %*09"):) mya&.
in the /evonian %*09"):) mya&.
There are about !2,000 species of ferns in the world. <ost species are tropical. There are about !2,000 species of ferns in the world. <ost species are tropical.
There are about )0 species of ferns in 6.1.-. and Canada.There are about )0 species of ferns in 6.1.-. and Canada.
Costa =ica has over !,000 species.Costa =ica has over !,000 species.
hilippines has over 90 species.hilippines has over 90 species.
•
• 1porophyte is differentiated into true roots, stem %rhi#ome& and leaves %megaphylls&.1porophyte is differentiated into true roots, stem %rhi#ome& and leaves %megaphylls&.
•
• Leaves usually differentiated into 1tipe %petiole& and blade with a central rachis or vein.Leaves usually differentiated into 1tipe %petiole& and blade with a central rachis or vein.
•
• <ost ferns are homosporous a few auatic genera are heterosporous.<ost ferns are homosporous a few auatic genera are heterosporous.
•
• The sporangia are produced in clusters calledThe sporangia are produced in clusters called or%or% %sing. %sing. or#or#.& the sori can be arranged in.& the sori can be arranged in
various patterns, e. g. rows or lines. various patterns, e. g. rows or lines.
COAL FORESTS COAL FORESTS
The Lycophyta and terophyta represent the modern lineages of seedless vascular plants that The Lycophyta and terophyta represent the modern lineages of seedless vascular plants that formed forests during the Carboniferous period about 290"):) million years ago.
formed forests during the Carboniferous period about 290"):) million years ago.
The coal beds, oil fields and natural gas deposits that are mined in modern times are derived The coal beds, oil fields and natural gas deposits that are mined in modern times are derived from these ancient forests. >rom there comes the name fossil fuels.
from these ancient forests. >rom there comes the name fossil fuels.
/uring the Carboniferous Europe and @orth -merica were closer to the euator and covered /uring the Carboniferous Europe and @orth -merica were closer to the euator and covered with e(tensive swamps. -s plants died, their body did not completely decay in the stagnant with e(tensive swamps. -s plants died, their body did not completely decay in the stagnant water and great depths of organic material accumulated forming peat.
water and great depths of organic material accumulated forming peat.
These layers of peat were later covered by sediments that pressed the peat. ressure and heat These layers of peat were later covered by sediments that pressed the peat. ressure and heat converted the peat into coal, petroleum and gas.
