Lab 8 - Primitive plants -Bryophytes,Ferns and Fern Allies

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Introduction come Bryophytes - Mosses, Liverworts,and Hornworts

As us pass native mosses come ferns, we check out a gradual change fromprimitiveto contemporary traits. There room two significant trends friend should emphasis on intoday"slab. The very first is a change in life cycles, the second is a changeinbasic inner structure.

You are watching: Why must bryophytes live in moist environments

First, all plants undergo an alternation the generations,between a haploid gametophyte stage and a diploid sporophytestage. In the many primitive plants, like mosses, the gametophyte isdominant(i.e. It"s large and green). In higher plants favor ferns and also fern allies,the sporophyte phase is dominant. Gametophytes produce gametes (spermandeggs) in a distinct structure referred to as a gametangium (-ia), whilesporophytesproduce spores in a one-of-a-kind structure called a sporangium(-ia).

Second, every plants need to obtain water to your cells.Primitivebryophyteslike mosses and also liverworts space so little that they can rely ~ above diffusionto move water in and also out that the plant. Mosses have a couple of strands ofwaterconducting tissue in their main stem, however nothing like the huge andwell arranged network of tube in tracheophytes, or "tubeplants".The vascular organization in the much more advanced ferns and "fernallies"are comprised of xylem and phloem, which command water,nutrients,and food throughout the tree body. We"ll look at at these tissues in alaterlab.

Bryophytes likewise need a moist atmosphere to reproduce. Theirflagellatedsperm need to swim through water to with the egg. For this reason mosses andliverwortsare restricted to moist habitats. There room no mosses in the desert.Butmosses room surprisingly resistant to drying up, and can make it through underveryharsh conditions. Mosses space the most abundant tree in both theArcticand the Antarctic. Asexual reproduction in bryophytes is accomplishedbyfragmentation or by tiny vegetative "sprouts" called gemmae,whichform in special tiny structures dubbed gemmae cups.

Mosses and liverworts room lumped with each other as bryophytes,plantslacking true vascular tissues, and sharing a variety of other primitivetraits. They additionally lack true stems, roots, or leaves, despite they havecellsthat carry out these general functions. The leafy environment-friendly plant that we seewhen us look at a moss or a liverwort is yes, really the gametophyte,which is the leading stage in every bryophytes. The sporophytesofbryophytes carry out not have actually a free-living existence. Castle grow straight outof the fertilized egg in the archegonia, and remain dependent on theparentgametophyte for your nutrition.

Characteristics of Divisions

Division Bryophyta - (9,500 sp.) - mosses, Mnium, Sphagnum

Mosses come in two straightforward types, a cushiony type, with erect stalks,and a feather type, which develops flattened mats of low-lying and highlybranched moss plants. In both cases, the leafy green gametophytes aredioeciousThey can be male plants, with antheridia at the peak of the plant, orfemaleplants, v archegonia in ~ the top. Remember that these gametophytesarealways haploid (1N) plants.

Sperm are produced within each antheridium, and an egg ineacharchegonium.Because the tree is currently haploid, this gametes deserve to be created bymitosis,simple cell division. The sperm swims come the archegonia through a thinfilm of water, drawn by a chemistry attractant produced by the femaleplant,then swims under the neck that the archegonia to the egg. A an excellent morningdewis an ext than sufficient water for the sperm come swim. Once the spermentersthe archegonia, the fuses through the egg. The 2N zygote establishes into adiploidsporophyte plant, a tiny stalk that grows straight out of the top ofthearchegonium. This stalk is at first green, and photosynthetic, butlaterturns brown and also becomes basically a parasite on the femalegametophyte.

The sporophyte plant is composed of a stalk, and also a tiny capsuleon the top. In ~ the capsule, cells undergo meiosis to producetetradsof haploid spores. When the capsule is ripe, its hinged lid oroperculumopens up, and also the spores room quickly dispersed by wind and water. Thesporesgerminate right into a tiny green thread, i m sorry looks choose a straightforward strand ofgreen algae. This similarity is one much more clue the bryophytes aredescendedfrom green algae. This beforehand threadlike stage is dubbed the protonema(= an initial thread, many = protonemata, like stigma/stigmata). The newadultgametophytes prosper from a tiny bud that develops on the protonema.Eventuallythese gametophytes will thrive to develop gametes, and the entirety cyclewillstart end again. Mosses can also reproduce asexually through fragmentationor by growing little vegetative buds called gemma, which can break offand flourish into a new plant .

While bryophytes in basic are an ext interesting 보다 important, inthe normal sense, a conspicuous exemption are mosses the the genus Sphagnum.Sphagnummoss forms thick mats which come to be compressed right into peat, which deserve to beusedas fuel, return it’s an extremely smoky. Peat likewise contains various other plants suchas reeds, that thrive amid the sphagnum. In dried form, peat moss isremarkablyabsorbent and, and has been supplied for diapers, because that enriching bad gardensoils, and also as a ar dressing because that wounds. Whereas cotton absorbs 4-6timesits dried weight, dried sphagnum deserve to absorb 20 times its own weight influids!Peat bogs are an extremely important and also interesting ecosystems. Sphagnummosses significantly increase regional acidity by release H+ ions, and also the pHof peat bogs have the right to drop come 4 or lower, possibly the most acidic naturalenvironment.Peat bogs cover about 1% of the Earth’s soil surface, an area abouthalfthe dimension of the unified States.

Division Hepaticophyta - (9,000 sp.), liverworts, Marchantia,Conocephalum, Porella

Liverworts have actually the most basic bodies of all the environment-friendly plants. Thegametophyte,the dominant stage, looks favor a level scaly leaf, with significant lobes.It looks for every the human being like a tiny flattened liver, hence thescientificname hepatico-phyta = liver plant. During the middle Ages, thissimilaritycaused doctors to prescribe liverwort for illness of the liver.Accordingto the theory of Signatures the Creator had designed all of nature,includingplants, with our welfare in mind. People believed that plants had beenintentionally designed to resemble the offal of the body they weresupposedto heal! hence liver-wort, wyrt gift the Anglo-Saxon word for herb.Theshape that the liverwort was the signature that the Creator in nature. Canyou assumption: v what walnuts were claimed to cure ? (diseases the thebrain)

Liverworts re-publishing the basic properties the bryophytes, yet are notveryclosely pertained to mosses or hornworts. Numerous botanists think castle mayhaveevolved independently, native a different group of green algae. For onething,liverworts don’t keep food as starch yet as oils. If you acquire theaquaticliverwort Porella in lab, take a sniff that the jar, however not toodeep!It smells that rancid oils, oils the went a tiny funky while the plantwas being shipped. Another characteristic distinctive to liverworts is theirlack of stomata, i beg your pardon are found in all various other plants, including mossesand hornworts.

In many types of liverworts, such together Marchantia, the oneyouwill most most likely see in lab, the antheridia and archegonia space not ontopof the plant, but hanging down from the underside of odd littlestructuresthat look choose tiny umbrellas. (These umbrella-shaped structures arecalledthe antheridiophore and also archegoniophore). The bi-flagellated spermswimsto the egg, and also fertilization takes place to type a diploid (2N)zygote.The tiny diploid sporophytes, which remain attrached to the parentplant,have a very straightforward structure. Meiosis within the sporophyte to produce anumber the haploid spores. These spores are surrounded through curious longandtwisted moist cells called elaters. As soon as the capsule dries and also bursts,the elaters twist and jerk about in a means that scatters the spores inall directions. Liverworts can likewise reproduce asexually by method ofspecialstructures called gemmae cups. These little cups deserve to be easilyseenon the surface of the plant. Each gemma cup has a number of tinyplantletscalled gemmae, and also a single drop the water will disperse them. Theselittlevegetative “clones” will certainly then grow into a brand-new gametophyte.

Division Anthocerophyta - (100 sp.), hornworts, Anthoceros

The green gametophytes of the hornwort look an extremely much prefer aliverwort.But their small sporophytes more closely resemble those the mosses. Thesporophytes flourish out that the gametophyte, and look like a small uprighthorn. Choose mosses, hornworts have stomata, and also so are most likely morecloselyrelated to mosses and also other plants 보다 to the liverworts lock matresemble.These plants are symbiotic v the cyanobacteria Nostoc. Thecyanobacteriafixes nitrogen because that the hornwort.

Taxonomy

Kingdom Plantae

Bryophytes

Division Bryophyta - mosses (Mnium, Sphagnum; fr.Gr.bryon= moss)

Division Hepaticophyta - liverworts (Marchantia,Conocephalum,Porella; fr.Gr. Hepato = liver)

Division Anthocerophyta - hornworts (= Anthocerotophyta; Anthoceros;fr.Granthos = flower, keras = horn)

Terms alternation the generations gametophyte gametangium (-ia) archegonium (-ia) antheridium (-ia) sporophyte sporangium (-ia) spore capsule protonema vascular mechanism gemmae gemmae cupTo Do and View

Examine the life mosses on display. Notice the tiny capsuleson peak of the tiny sporophytes. Mosses generally prosper in one of twogrowthtypes: cushiony moss and feathery moss.

Examine slides the the antheridia and archegonia. The sausageshaped antheridia develop sperm, and also the flask shaped archegoniaproduces eggs.

Examine slides of the moss capsule, and identify the spores.

Examine slides the the protonema. What form of algaedoesit repeat you of? This same is extr evidence the greenalgaegave increase to all higher plants.

Examine the terrestrial liverworts Marchantia and also Conencephalum(oneor both have to be ~ above display). Just how does their expansion habit differ fromthat the the mosses? have the right to you see any kind of gemmae cups on the uppersurfaceof this plants?

Examine slides the the liverwort Marchantia.

Examine the aquatic liverworts like PorellaandRiccia(one or both must be ~ above display). Notice how they differ from themoreterrestrial forms of liverwort.

Look at the kept liverworts, and observe their distinctreproductive frameworks (they look at like little green umbrellas). Howdoestheir life cycle different from mosses?

Examine slides that the hornwort Anthocerophyta.

Things to Remember

Know the life bicycle of the moss in detail, and be may be torecognizethe assorted stages.

Hint: Be sure you understand the general life bicycle ofplants,and have the right to tell which stages space haploid gametophytes (1N) or diploidsporophytes(2N). We"ll discover several life cycles in lecture and in laboratory (moss,fern,pine, flower plant), but all of them space variations ~ above the samebasictheme.

Ecological, Evolutionary, and also Economic Importance

Mosses are essential in landscaping and gardening, specifically peatmoss(Sphagnum).

Peat moss (Sphagnum) has actually been provided historically as dressingsfor wounds.

Peat moss can be provided as fuel.

Mosses space the most primitive living land plants.

Hornworts save on computer symbiotic swarms of the cyanobacteria Nostoc.

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shining society moss

Introduction come Tracheophytes - Ferns and Fern Allies

Tracheophytes (vascular plants) completed the conquest of theearth’s surface begun by the an ext primitive bryophytes. Simply as theevolutionof spores to be the vital to the invasion of the land surface ar bybryophytes,the creation of complicated vascular tissues let tracheophytes completetheconquest of dried land. Over there are about 250,000 species of vascularplants,grouped in nine divisions. Tracheophytes all have actually a fine developedroot-shootsystem, with highly dedicated roots, stems, and also leaves, andspecializedvasculartissue (xylem and also phloem) that function like miniature tubes toconductfood, water, and also nutrients transparent the plant. Because ferns and fernallies posses true vascular tissues, lock can flourish to be lot largerandthicker than the bryophytes.

The ferns and fern allies (non-seed tracheophytes) mark two majorevolutionarystrides. In these and also in all more advanced plants, the leafy eco-friendly diploidsporophyte currently becomes the leading stage. The small gametophytemay be one of two people autotropophic (like the fern prothallus) orheterotrophic(like the gametophytes of some lycopsids), and also is generally free livingand elevation of the parental sporophyte. Unequal the vascularsporophytes,the gametophytes have actually no vascular tissue at all. This gametophytes aretherefore an extremely small, and also develop best in moist areas, whereby they canabsorbwater straight from your surroundings.

Like the bryophytes, ferns and fern allies space still limited tomoisthabitats. Their flagellated sperm require a slim film that water to swimbetweenthe antheridium and the archegonium. And also when the baby sporophyte growsup indigenous the gametophyte, it is exposed come desiccation (drying up). Thisbasic strategy the a free-swimming sperm and also a non-motile egg is sharedby plants, animals, and also algae. It renders sense, because it means onlyoneset the gametes needs to make the perilous journey external of theorganism.

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ground pine tree (Lycopodium) reflecting strobili

The ferns and also fern allies germinate from spores. This plants aremostlyhomosporous- their spores space identical and also you can"t differentiate which willgrow into male or female plants. Castle are also monoecious -boththe archegonia and also antheridia (male and female reproductive structures)are borne ~ above the same plant. Contrast these primitive vascular plantswiththe more advanced seeds plants, the gymnosperms and also angiosperms, whichgerminatefrom seeds quite than native spores. Particle plants space all heterosporous.It is simple to identify the larger female megaspore fromthesmaller masculine microspore. The sperm of seeds plants have noflagella.They lack antheridia, and also only a couple of still have actually an archegonia. Unlikethemore primitive ferns and fern allies, seed tree are greatly dioecious,having different male and also female plants.

In numerous of these primitive plants, specific leaves are specializedforreproduction. These modified leaves, or sporophylls, be affected by each other thesporangiaat their bases. This sporophylls normally branch out from a shortenedstem,forming a club shaped structure called a strobilus. The pineconeand the flower are sophisticated variations on these primitive strobili.

There room four departments of non-seed tracheophytes, vascular plantsthat blee by method of spores, the Psilophyta, Lycophyta,Sphenophyta,and Pterophyta. Prior to these non-seed tracheophytes evolved, thebryophyteswere the dominant kind of plant life. The evolutionary edge of having amore reliable conducting system, and a well-developed root-shootsystemenabled them to outcompete bryophytes. If you’re lucky enough to seegroundpine or various other club mosses cultivation in the shade of a huge pine tree,thinkfor a moment around how these tiny plants were once the master of theplanet,forming huge forests with trunks indigenous 20 come 100 feet tall!

Taxonomy

Kingdom Plantae

Tracheophytes (vascular tissue, no seeds)

Division Lycophyta - club moss, quillworts (Lycopodium,Selaginella)

Division Sphenophyta - horsetails (Equisetum; fr.L.equus= horse)

Division Psilophyta - whisk fern (Psilotum)

Division Pterophyta - true ferns (Pteris; fr.Gr.pteridion= small wing)

Terms homosporous heterosporous megaspores microspores rhizomes sporophylls strobilus (-i) sori indusium (-ia) prothallus fiddleheadsCharacteristics of Divisions

Division Psilophyta - (fr Gr. Psilo = smooth), whiskferns,Psilotum

There are just two life genera the whisk ferns, single survivors that alarge and widespread group of early land plants. In enhancement to thelivingDivision Psilophyta, the psilopsids, there room two extinct divisions ofprimeval vascular plants. The primitive whisk ferns resemble theseextinctpioneers in countless ways. They room the just living vascular tree thatlacka root-shoot system, a characteristic castle share through both extinctDivisionsof ancestral vascular plants. Some current molecular proof suggeststhatone, or also both, of the living genera that psilopsids might actually bemoreclosely concerned ferns, prefer a fern that has reverted come moreprimitivetraits. If this is true, climate Psilophyta will sign up with the ranks of thenumerousextinct departments of plants.

Psilopsids are discovered in tropical and subtropical areas, and occursthroughoutthe southerly US. I once discovered one cultivation on my ago porch under theleavesof a spider plant. Whisk ferns are a common weed in greenhouses alloverthe world. Lock are basic green upright stems, with dichotomousbranching.They have no leaves, and also no true roots. The outer tissues that the stemdoall the photosynthesizing. A section of the stem referred to as a rhizome runsalong the ground, or just listed below it. A rhizome is a horizontalstemthat spreads the plant around. Roots thrive out the bottom the therhizome,and a new plant deserve to arise in ~ the same suggest from the top.

The eco-friendly stem-like tree is the diploid sporophyte, the dominantstagein the life cycle. In the little sporangia (bright yellow) the formalongthe top stems, the spore mom cell creates haploid spores by meiosis.Their gametophytes room tiny little thread-like underground tree thatlack chlorophyll, and live together heterotrophs in the soil, looking andactingmuch like a tiny fungi. That actually consists of a symbiotic fungi, thesamemycorrhizae the live in the rhizomes the the adult sporophyte.

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Division Lycophyta - (1,000 sp., fr. Gr. Lycos=wolf), clubmosses,quillworts, Lycopodium (podus=foot)

Their are only five living genera that lycopsids, but at once fromthe far-off Devonian, about 400 mya, well into the Carboniferous, theywere the dominant type of vegetation top top the confront of the Earth. Now theyare lessened to a zero of their glorious past, inconspicuous littleplantsin the forest understory. The tropical types are tiny epiphytes(plantsthat grow on various other plants).

Their roots prosper from one-of-a-kind underground stems called rhizomes, asdo most of this primitive tracheophytes. In some types thesporophyllsare combined in with the scale-like leaves. In numerous species, thesporophyllsare organized into strobili, hence the usual name of “club moss”. Thesperm swim under the strobilus to the archegonia, and the zygote thatformsis kept in the cone, i m sorry ripens and falls come the ground. Thegametophytesare independent and also free-living, They are curious creatures the lookandact nothing choose their sporophyte parents. They have the right to be eitherheterotrophicor autotrophic, and usually have a symbiotic fungi connected withthem.Many of the lycopsids are heterosporous. Selaginella is a goodexampleof a heterosporous plant.

Division Sphenophyta - (15 sp., one genus, fr. Gr.sphen=wedge),horsetails, Equisitum

In garbage places, disturbed locations like trails and railroad beds, andin odd corners the fields and also forests you could find another little plantquietly dreaming that its former splendor, the horsetail. Horsetailsappearedin the late Devonian, and were amongst the leading forest trees forhundredsof millions of years. Just one genus that Sphenophyta quiet exists, thegenusEquisetum,and it may be the earliest living genus of plants on earth. Horsetailstoweredamong the Carboniferous forests, getting to heights that 30-60 feet. Muchofthe charcoal deposits we exploit for fuel this particular day were formed from horsetailsand other trees during the Carboniferous, toward the finish of thePaleozoic.

Horsetails have true roots, stems, and also leaves, though the leaves arelittle more than flattened stems. Your hollow, ribbed stems arejointed,kind of like a stalk that bamboo, and a whorl of pipeline arises at eachjoint.The plants are spread vegetatively by rhizomes. The stems feeling veryrough,because the epidermal tissues room impregnated through tiny grains ofsilica(sand). This more than likely helps protect the plant against herbivores. Theserough stems make this plant appropriate for pioneer women to use forscrubbingpots and pans, thus its other typical name, “scouring rush”.

The environment-friendly plant we view is the diploid sporophyte generation. Thestalkscan be extremely branched vegetative stalks, which actually look likehorsetails, or right unbranched reproductive stalks, which are tippedwitha big strobilus containing the sporangia. The homosporous sporesdevelopinto a teeny-tiny green gametophyte, simply a few mm long, the lookslikethe gametophyte of a fern. The gametophyte is haploid, free-living, andautotrophic.

Division Pterophyta - (12,000 sp., fr. Gr. Pteridion=littlewing),ferns

Ferns probably evolved from the psilopsids, at some point in theDevonian,relatively beforehand in land tree evolution. Lock are really abundant anddiverse, ranging in dimension from a solitary centimeter to tree 24 meterstallwith 5 meter fronds. Ferns have actually been better competitors with seedplantsthan various other seedless vascular plants, and also are a conspicuous component of thelandscape throughout the world, however especially in the tropics, where75%of their 12,000 types occur.

Ferns are fairly advanced plants, v true roots, tribe andleaves.The blade of the fern is dubbed a frond, and also the little individualleafletsare referred to as pinnae. Ferns have true leaves, what botanists callmacrophylls.While the pipeline of much more primitive plants, which room calledmicrophylls,are simply extensions of the epidermis of the stem, the pipeline of fernsand higher plants were formed as a web of tissue stretched betweensmallterminal branches. The pipeline of higher plants, and also the modifiedleaves that consist of the pine cone and also the flower.

The life bike of the fern is typical of various other non-seed vascularplants.The leafy green plant is the sporophyte. Fertile fronds developsclustersof small sporangia top top the underside of the frond. This clusters ofsporangiaare dubbed sori (sing. Sorus). Sori are often defended by atinyumbrella-like cap called an indusium (-ia). Ferns space mostlyhomosporous,though some room heterosporous. The heterosporous state is a moreadvancedcondition, that appears to have developed independently in several groupsofplants.

The haploid spores are created by meiosis inside the sporangium. She ejected in a miniature explosion caused by the unequal dry ofthealternate thick and also thin-walled cells the line the external surface. Thetop pulls slowly earlier until it reaches a crucial point and then snapsforward at an significant speed. At that dimension scale, the expulsion offernspores is one of the many explosive occasions in nature. The sporesgerminateinto small gametophytes. The little heart shame gametophyte is called aprothallus,literally “first-body” (pl prothalli). The prothallus has no vasculartissue.Its tiny size allows it rely completely on diffusion. Its tiny rhizoidsareassociated through mycorrhizal fungi. The small prothallus is green, andphotosynthetic, and also bears one of two people antheridia and archegonia, orsometimesboth together, on its upper surface ar (lab slides have both on sameprothallus).The archegonia are constantly found in ~ the arch the the heart, and also theantheridiaare tucked away amongst the tiny rhizoids at the various other end. The spermswimsto the egg to fuse right into a diploid zygote. The brand-new sporophyte growsdirectlyout of the peak of the gametophyte. When it very first begins to uncurl, thefrond looks prefer the scrolled neck of a violin or fiddle, and also thisstageof breakthrough is dubbed a fiddlehead.

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To Do and View

Examine the living lycopsids on display. Why room they calledclub mosses? notice that quillworts and Selaginella are verydifferentin appearance from the society mosses.

Examine slides that Selaginella"s strobilus. Determine megasporesand microspores.

Examine the life horsetails top top display. An alert theprominentstrobiliofthe reproductive stalks, and also the bushy growth type of the vegetativestalks(if available).

Examine the living whisk ferns ~ above display. Psilopsidshave a simple dichotomous branching pattern. You might see tiny yellowsporangiaon the branches. Whisk ferns absence strobili. These primitive tree areclosely related to ferns.

Examine the living ferns on display. Deserve to you see any type of fiddleheads?Look for the rhizomes. Rhizomes are modified horizontal stemsbearingroots, that operation along or simply underneath the ground, and also spread fernsandfern allies around.

Examine the living fern prothallus on display under adissectingmicroscope. Note its characteristic love shape. Part prothalli mayhavea tiny brand-new fern arising from the notch of the "arch" heart, whereby thearchegoniaarelocated.

Examine slides of the prothallus: find the archegonia(can you view an egg?).

Examine the fern leaflet on screen under the dissectingmicroscope.Notice the prominent indusia, and the little sporangiapeekingout native beneath. You"ll watch a few groups the sporangia that have losttheirindusium. If you"re lucky, together the warm of the microscope dries the end theleaflet, you could see the sporangia eject that is spores. Yet don"tblink- it"s one of the fastest and also most explosive plot in nature. Use highpowerto watch the spores.

Examine slides of the sori and indusia; usage high powerto watch the spores.

Things to Remember

Know the life bicycle of the fern. Acknowledge specimens andslidesof the miscellaneous stages.

Economic, Ecological, and also Evolutionary Importance

Ferns and also fern allies are mostly responsible for our moderndepositsof coal.

The fiddleheads that some species of ferns room edible.

See more: What Is 250 Ml Of Water To Grams ? How Much Is 250 Ml Of Water In Grams

Ferns are necessary for the florist, gardening and also landscapeindustries.

Consider This

Why room all these plants restricted to wet habitats?

Which team of protists provided rise to this plants? (How execute we know?)

Why is the epidermis that the horsetail for this reason rough? What does that needprotectionfrom?

All that the fern allies in this lab as soon as towered 50-100 feet or more.What happened?

Links come Explore

Bryophyte taxonomy, images, and an ext at:

http://bryophytes.plant.siu.edu/

Get info around bryophytes from the Missouri botanical Garden at:

http://www.mobot.org/mobot/tropicos/most/

Lie down amongst the ferns in ~ the American Fern Society, shot theirlengthylist of links:

http://amerfernsoc.org

Basic details on ferns and fern allies, finish with images, courtesyof Texas A&M:

http://www.csdl.tamu.edu/FLORA/fsb/fsbfern1.htm

Look for ferns ~ above the "tree that life" at

http://phylogeny.arizona.edu/tree/eukaryotes/green_plants/embryophytes/filicopsida/filicopsida.html