Lab 8 - Primitive tree -Bryophytes,Ferns and Fern Allies
As us pass native mosses to ferns, we check out a gradual shift fromprimitiveto modern traits. There room two significant trends friend should emphasis on intoday"slab. The an initial is a change in life cycles, the 2nd is a changeinbasic internal structure.
You are watching: Compared to the moss, the fern is better adapted to life on land because the fern
First, all tree undergo an alternation the generations,between a haploid gametophyte stage and also a diploid sporophytestage. In the most primitive plants, like mosses, the gametophyte isdominant(i.e. It"s large and green). In higher plants choose ferns and also fern allies,the sporophyte phase is dominant. Gametophytes create gametes (spermandeggs) in a special structure dubbed a gametangium (-ia), whilesporophytesproduce spores in a unique structure dubbed a sporangium(-ia).
Second, every plants need to get water to their cells.Primitivebryophyteslike mosses and liverworts room so tiny that they can rely ~ above diffusionto move water in and also out of the plant. Mosses have a few strands ofwaterconducting tissue in their main stem, yet nothing choose the large andwell organized network of tubes in tracheophytes, or "tubeplants".The vascular organization in the an ext advanced ferns and "fernallies"are comprised of xylem and phloem, which conduct water,nutrients,and food throughout the tree body. We"ll look at at these tissues in alaterlab.
Bryophytes also need a moist setting to reproduce. Theirflagellatedsperm must swim through water to with the egg. So mosses andliverwortsare limited to moist habitats. There room no mosses in the desert.Butmosses are surprisingly resistant to dry up, and can survive underveryharsh conditions. Mosses room the many abundant plants in both theArcticand the Antarctic. Asexual reproduction in bryophytes is accomplishedbyfragmentation or by small vegetative "sprouts" called gemmae,whichform in special little structures called gemmae cups.
Mosses and liverworts room lumped together as bryophytes,plantslacking true vascular tissues, and also sharing a variety of other primitivetraits. They also lack true stems, roots, or leaves, though they havecellsthat execute these general functions. The leafy eco-friendly plant that us seewhen us look at a moss or a liverwort is really the gametophyte,which is the leading stage in every bryophytes. The sporophytesofbryophytes carry out not have a free-living existence. They grow straight outof the fertilized egg in the archegonia, and remain dependency on theparentgametophyte for your nutrition.Characteristics the 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 also highlybranched moss plants. In both cases, the leafy environment-friendly gametophytes aredioeciousThey have the right to be masculine plants, through antheridia at the peak of the plant, orfemaleplants, with archegonia at the top. Remember the these gametophytesarealways haploid (1N) plants.
Sperm are created within each antheridium, and also an egg ineacharchegonium.Because the tree is currently haploid, this gametes have the right to be developed bymitosis,simple cabinet division. The sperm swims to the archegonia v a thinfilm of water, attracted by a chemistry attractant produced by the femaleplant,then swims down the neck the the archegonia to the egg. A an excellent morningdewis much more than sufficient water for the sperm come swim. Once the spermentersthe archegonia, the fuses v the egg. The 2N zygote establishes into adiploidsporophyte plant, a little stalk that grows directly out the the height ofthearchegonium. This stalk is initially green, and also photosynthetic, butlaterturns brown and also becomes essentially a parasite on the femalegametophyte.
The sporophyte plant consists of a stalk, and also a tiny capsuleon the top. In ~ the capsule, cells undergo meiosis come producetetradsof haploid spores. When the capsule is ripe, the hinged lid oroperculumopens up, and also the spores are quickly dispersed by wind and water. Thesporesgerminate right into a tiny green thread, i beg your pardon looks choose a an easy strand ofgreen algae. This similarity is one more clue the bryophytes aredescendedfrom eco-friendly algae. This early on threadlike phase is dubbed the protonema(= first thread, many = protonemata, choose stigma/stigmata). The newadultgametophytes thrive from a tiny bud that establishes on the protonema.Eventuallythese gametophytes will flourish to create gametes, and the whole cyclewillstart end again. Mosses can also reproduce asexually by fragmentationor through growing small vegetative buds referred to as gemma, which have the right to break offand grow into a brand-new plant .
While bryophytes in general are an ext interesting 보다 important, inthe usual sense, a conspicuous exemption are mosses the the genus Sphagnum.Sphagnummoss forms thick mats which end up being compressed right into peat, which deserve to beusedas fuel, return it’s really smoky. Peat additionally contains other plants suchas reeds, that prosper amid the sphagnum. In dried form, peat moss isremarkablyabsorbent and, and has been used for diapers, for enriching poor gardensoils, and as a ar dressing because that wounds. Whereas noodle absorbs 4-6timesits dry weight, dried sphagnum have the right to absorb 20 times its own weight influids!Peat bogs are very important and also interesting ecosystems. Sphagnummosses considerably increase neighborhood acidity by release H+ ions, and the pHof peat bogs deserve to drop come 4 or lower, probably the many acidic naturalenvironment.Peat bogs cover around 1% of the Earth’s soil surface, one area abouthalfthe dimension of the joined States.
Division Hepaticophyta - (9,000 sp.), liverworts, Marchantia,Conocephalum, Porella
Liverworts have actually the easiest bodies of all the green plants. Thegametophyte,the dominant stage, looks prefer a flat scaly leaf, with prominent lobes.It look at for all the human being like a tiny flattened liver, therefore thescientificname hepatico-phyta = liver plant. During the center Ages, thissimilaritycaused doctors to prescribe liverwort for diseases of the liver.Accordingto the doctrine of Signatures the Creator had designed every one of nature,includingplants, through our welfare in mind. People thought that plants had beenintentionally designed to resemble the offal of the human body they weresupposedto heal! hence liver-wort, wyrt gift the Anglo-Saxon word because that herb.Theshape that the liverwort to be the signature that the Creator in nature. Canyou guess: v what walnuts were claimed to cure ? (diseases of thebrain)
Liverworts re-superstructure the general properties of bryophytes, but are notveryclosely pertained to mosses or hornworts. Numerous botanists think they mayhaveevolved independently, native a different group of eco-friendly algae. Because that onething,liverworts don’t store food together starch yet as oils. If you gain theaquaticliverwort Porella in lab, take a sniff that the jar, yet not toodeep!It smells the rancid oils, oils the went a tiny funky when the plantwas gift shipped. Another characteristic distinct to liverworts is theirlack of stomata, i beg your pardon are uncovered in all other plants, consisting of mossesand hornworts.
In many varieties of liverworts, such together Marchantia, the oneyouwill most most likely see in lab, the antheridia and also archegonia room not ontopof the plant, yet hanging under from the underside of weird littlestructuresthat look like tiny umbrellas. (These umbrella-shaped structures arecalledthe antheridiophore and also archegoniophore). The bi-flagellated spermswimsto the egg, and also fertilization takes ar to form a diploid (2N)zygote.The tiny diploid sporophytes, which continue to be attrached to the parentplant,have a very simple structure. Meiosis in ~ the sporophyte produce anumber of haploid spores. This spores space surrounded through curious longandtwisted moist cells referred to as elaters. As soon as the capsule dries and bursts,the elaters twist and also jerk roughly in a method that scatters the spores inall directions. Liverworts can also reproduce asexually by means ofspecialstructures called gemmae cups. These little cups have the right to be easilyseenon the surface of the plant. Every gemma cup contains a number of tinyplantletscalled gemmae, and also a solitary drop that water will certainly disperse them. Theselittlevegetative “clones” will certainly then grow into a new gametophyte.
Division Anthocerophyta - (100 sp.), hornworts, Anthoceros
The green gametophytes of the hornwort look very much prefer aliverwort.But their small sporophytes much more closely resemble those that mosses. Thesporophytes flourish out the the gametophyte, and look like a little uprighthorn. Prefer mosses, hornworts have stomata, and so are probably morecloselyrelated come mosses and also other plants than to the liverworts lock matresemble.These plants room symbiotic with the cyanobacteria Nostoc. Thecyanobacteriafixes nitrogen for the hornwort.Taxonomy
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 little capsuleson height of the tiny sporophytes. Mosses generally grow in among twogrowthtypes: cushiony moss and also feathery moss.
Examine slides the the antheridia and archegonia. The sausageshaped antheridia develop sperm, and the flask shame archegoniaproduces eggs.
Examine slides of the moss capsule, and also identify the spores.
Examine slides that the protonema. What form of algaedoesit remind you of? This same is added evidence the greenalgaegave increase to all greater plants.
Examine the terrestrial liverworts Marchantia and also Conencephalum(oneor both need to be ~ above display). How does their expansion habit differ fromthat of the mosses? deserve to you see any gemmae cups top top the uppersurfaceof these plants?
Examine slides of the liverwort Marchantia.
Examine the aquatic liverworts prefer PorellaandRiccia(one or both must be top top display). Notice how they different from themoreterrestrial forms of liverwort.
Look at the preserved liverworts, and also observe your distinctreproductive frameworks (they look like little green umbrellas). Howdoestheir life cycle different from mosses?
Examine slides of the hornwort Anthocerophyta.Things come Remember
Know the life bike of the moss in detail, and also be may be torecognizethe assorted stages.
Hint: Be sure you recognize the basic life bike ofplants,and have the right to tell i m sorry stages are haploid gametophytes (1N) or diploidsporophytes(2N). We"ll find out several life cycles in lecture and also in lab (moss,fern,pine, flower plant), but all of them space variations ~ above the samebasictheme.Ecological, Evolutionary, and also Economic Importance
Mosses are important in landscaping and gardening, especially peatmoss(Sphagnum).
Peat moss (Sphagnum) has actually been supplied historically as dressingsfor wounds.
Peat moss deserve to be offered as fuel.
Mosses room the many primitive life land plants.
Hornworts save symbiotic colonies of the cyanobacteria Nostoc.
shining society moss
Introduction to Tracheophytes - Ferns and Fern Allies
Tracheophytes (vascular plants) completed the occupation of theearth’s surface started by the much more primitive bryophytes. Just as theevolutionof spores was the an essential to the invasion of the land surface bybryophytes,the creation of complex vascular organization let tracheophytes completetheconquest of dry land. There are around 250,000 types of vascularplants,grouped in nine divisions. Tracheophytes all have a well developedroot-shootsystem, v highly committed roots, stems, and also leaves, andspecializedvasculartissue (xylem and also phloem) that role like miniature tubes toconductfood, water, and nutrients throughout the plant. Due to the fact that ferns and also fernallies posses true vascular tissues, castle can flourish to be lot largerandthicker 보다 the bryophytes.
The ferns and also fern allies (non-seed tracheophytes) mark two majorevolutionarystrides. In these and in all more advanced plants, the leafy green diploidsporophyte currently becomes the leading stage. The tiny gametophytemay be either autotropophic (like the fern prothallus) orheterotrophic(like the gametophytes of part lycopsids), and is generally totally free livingand elevation of the parental sporophyte. Unlike the vascularsporophytes,the gametophytes have actually no vascular tissue at all. This gametophytes aretherefore really small, and also develop finest in moist areas, whereby they canabsorbwater directly from your surroundings.
Like the bryophytes, ferns and fern allies room still restricted tomoisthabitats. Your flagellated sperm require a thin film of water to swimbetweenthe antheridium and the archegonium. And when the baby sporophyte growsup indigenous the gametophyte, the is exposed come desiccation (drying up). Thisbasic strategy that a free-swimming sperm and a non-motile egg is sharedby plants, animals, and algae. It makes sense, due to the fact that it method onlyoneset of gametes needs to make the perilous journey external of theorganism.
ground pine (Lycopodium) showing strobili
The ferns and fern allies germinate native spores. These plants aremostlyhomosporous- their spores space identical and also you can"t differentiate which willgrow into male or mrs plants. They are also monoecious -boththe archegonia and also antheridia (male and female reproductive structures)are borne ~ above the exact same plant. Comparison these primitive vascular plantswiththe more advanced seed plants, the gymnosperms and angiosperms, whichgerminatefrom seeds quite than from spores. Seeds plants are all heterosporous.It is basic to differentiate the larger female megaspore fromthesmaller masculine microspore. The sperm of seeds plants have noflagella.They absence antheridia, and only a couple of still have actually an archegonia. Unlikethemore primitive ferns and also fern allies, seed tree are greatly dioecious,having different male and also female plants.
In numerous of this primitive plants, details leaves room specializedforreproduction. These modified leaves, or sporophylls, be affected by each other thesporangiaat your bases. This sporophylls generally branch out from a shortenedstem,forming a society shaped structure called a strobilus. The pineconeand the flower are sophisticated variations on this primitive strobili.
There are four divisions of non-seed tracheophytes, vascular plantsthat reproduce by method of spores, the Psilophyta, Lycophyta,Sphenophyta,and Pterophyta. Before these non-seed tracheophytes evolved, thebryophyteswere the dominant type of tree life. The evolutionary edge of having amore efficient conducting system, and also a well-developed root-shootsystemenabled them to outcompete bryophytes. If you’re lucky enough to seegroundpine or other club mosses farming in the the shade of a huge pine tree,thinkfor a moment about how these tiny plants were as soon as the masters of theplanet,forming substantial forests v trunks from 20 come 100 feet tall!Taxonomy
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= tiny 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 that whisk ferns, single survivors the alarge and also widespread group of early on land plants. In addition 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 only living vascular tree thatlacka root-shoot system, a characteristic lock share v both extinctDivisionsof ancestral vascular plants. Some recent molecular proof suggeststhatone, or even both, that the life genera of psilopsids might actually bemoreclosely concerned ferns, like a fern that has actually reverted come moreprimitivetraits. If this is true, climate Psilophyta will join the ranking of thenumerousextinct departments of plants.
Psilopsids are discovered in tropical and also subtropical areas, and occursthroughoutthe southern US. I once found one cultivation on my earlier porch under theleavesof a spider plant. Whisk ferns room a typical weed in greenhouses alloverthe world. They are basic green upright stems, v dichotomousbranching.They have actually no leaves, and no true roots. The outer tissues the the stemdoall the photosynthesizing. A section of the stem called 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 brand-new plant can arise in ~ the same point from the top.
The green stem-like plant is the diploid sporophyte, the dominantstagein the life cycle. In the small sporangia (bright yellow) that formalongthe top stems, the spore mommy cell develops haploid spores through meiosis.Their gametophytes are tiny small thread-like underground plants thatlack chlorophyll, and live together heterotrophs in the soil, spring andactingmuch like a small fungi. The actually includes a symbiotic fungi, thesamemycorrhizae that live in the rhizomes that the adult sporophyte.
Division Lycophyta - (1,000 sp., fr. Gr. Lycos=wolf), clubmosses,quillworts, Lycopodium (podus=foot)
Their space only five living genera that lycopsids, but at once fromthe remote Devonian, about 400 mya, well right into the Carboniferous, theywere the dominant form of vegetation top top the face of the Earth. Now theyare reduced to a shadow of their glorious past, inconspicuous littleplantsin the forest understory. The tropical species are little epiphytes(plantsthat grow on other plants).
Their roots flourish from special underground stems called rhizomes, asdo most of these primitive tracheophytes. In some varieties thesporophyllsare blended in with the scale-like leaves. In numerous species, thesporophyllsare organized into strobili, therefore the common name of “club moss”. Thesperm swim under the strobilus to the archegonia, and also the zygote thatformsis maintained in the cone, which ripens and also falls to the ground. Thegametophytesare independent and free-living, They space curious creatures the lookandact nothing favor their sporophyte parents. They can be eitherheterotrophicor autotrophic, and also usually have a symbiotic fungi associated withthem.Many the the lycopsids room heterosporous. Selaginella is a goodexampleof a heterosporous plant.
Division Sphenophyta - (15 sp., one genus, fr. Gr.sphen=wedge),horsetails, Equisitum
In waste places, disturbed locations like trails and railroad beds, andin odd corners of fields and forests you might find another small plantquietly dreaming that its previous splendor, the horsetail. Horsetailsappearedin the so late Devonian, and also were among the dominant forest trees forhundredsof countless 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 the 30-60 feet. Muchofthe charcoal deposits we exploit for fuel this day were developed from horsetailsand other trees throughout the Carboniferous, towards the end of thePaleozoic.
Horsetails have true roots, stems, and leaves, despite the pipeline arelittle an ext than flattened stems. Their hollow, ribbed stems arejointed,kind of choose a stalk of bamboo, and also a whorl of pipeline arises in ~ eachjoint.The plants space spread vegetatively through rhizomes. The stems feeling veryrough,because the epidermal tissues room impregnated through tiny seed ofsilica(sand). This more than likely helps protect the plant against herbivores. Theserough stems made this plant right for pioneer women to use forscrubbingpots and also pans, for this reason its other typical name, “scouring rush”.
The eco-friendly plant we view is the diploid sporophyte generation. Thestalkscan be extremely branched vegetative stalks, which in reality look likehorsetails, or directly unbranched reproductive stalks, which space tippedwitha big strobilus include the sporangia. The homosporous sporesdevelopinto a teeny-tiny eco-friendly gametophyte, simply a few mm long, that lookslikethe gametophyte of a fern. The gametophyte is haploid, free-living, andautotrophic.
Division Pterophyta - (12,000 sp., fr. Gr. Pteridion=littlewing),ferns
Ferns probably developed from the psilopsids, at some time in theDevonian,relatively early on in land tree evolution. Lock are really abundant anddiverse, ranging in dimension from a single centimeter to tree 24 meterstallwith 5 meter fronds. Ferns have been much better competitors v seedplantsthan other seedless vascular plants, and are a conspicuous part of thelandscape throughout the world, but especially in the tropics, where75%of your 12,000 species occur.
Ferns are reasonably advanced plants, with true roots, tribe andleaves.The blade of the fern is referred to as a frond, and the little individualleafletsare dubbed pinnae. Ferns have actually true leaves, what botanists callmacrophylls.While the pipeline of more primitive plants, which space calledmicrophylls,are simply expansions of the epidermis the the stem, the pipeline of fernsand higher plants were developed as a internet of tissue extended betweensmallterminal branches. The leaves of higher plants, and also the modifiedleaves that make up the jaw cone and also the flower.
The life cycle of the fern is usual of various other non-seed vascularplants.The leafy environment-friendly plant is the sporophyte. Productive fronds developsclustersof small sporangia top top the underside that the frond. This clusters ofsporangiaare called sori (sing. Sorus). Sori space often protected by atinyumbrella-like cap called an indusium (-ia). Ferns space mostlyhomosporous,though some are heterosporous. The heterosporous state is a moreadvancedcondition, that seems to have developed independently in numerous groupsofplants.
The haploid spores are developed by meiosis within the sporangium. She ejected in a miniature explosion caused by the unequal drying ofthealternate thick and also thin-walled cells that line the outer surface. Thetop traction slowly earlier until it reaches a an essential point and then snapsforward in ~ an significant speed. At that dimension scale, the expulsion offernspores is just one of the most explosive occasions in nature. The sporesgerminateinto tiny gametophytes. The small heart shame gametophyte is dubbed aprothallus,literally “first-body” (pl prothalli). The prothallus has no vasculartissue.Its tiny size allows it rely entirely on diffusion. Its tiny rhizoidsareassociated through mycorrhizal fungi. The small prothallus is green, andphotosynthetic, and bears either antheridia and archegonia, orsometimesboth together, on its upper surface (lab slides have actually both ~ above sameprothallus).The archegonia are constantly found at the arch of the heart, and theantheridiaare tucked away amongst the small rhizoids at the various other end. The spermswimsto the egg to fuse into a diploid zygote. The new sporophyte growsdirectlyout of the peak of the gametophyte. When it an initial begins to uncurl, thefrond looks choose the scrolled neck of a violin or fiddle, and thisstageof advance is dubbed a fiddlehead.
To Do and View
Examine the life lycopsids top top display. Why space they calledclub mosses? an alert that quillworts and Selaginella space verydifferentin appearance indigenous the society mosses.
Examine slides the Selaginella"s strobilus. Identify megasporesand microspores.
Examine the living horsetails ~ above display. An alert theprominentstrobiliofthe reproductive stalks, and the bushy growth kind of the vegetativestalks(if available).
Examine the life whisk ferns ~ above display. Psilopsidshave a straightforward dichotomous branching pattern. You may see tiny yellowsporangiaon the branches. Whisk ferns absence strobili. This primitive tree areclosely related to ferns.
Examine the living ferns on display. Deserve to you see any type of fiddleheads?Look because that the rhizomes. Rhizomes room modified horizontal stemsbearingroots, that operation along or simply underneath the ground, and spread fernsandfern allies around.
Examine the living fern prothallus on display screen under adissectingmicroscope. Note its characteristic heart shape. Part prothalli mayhavea tiny brand-new fern arising from the notch of the "arch" heart, whereby thearchegoniaarelocated.
Examine slides of the prothallus: discover the archegonia(can you check out an egg?).
Examine the fern leaflet on display screen under the dissectingmicroscope.Notice the significant indusia, and the tiny sporangiapeekingout indigenous beneath. You"ll view a couple of groups of sporangia that have losttheirindusium. If you"re lucky, together the warmth of the microscope dries out theleaflet, you can see the sporangia eject that is spores. However don"tblink- it"s among the fastest and most explosive acts in nature. Usage highpowerto watch the spores.
Examine slides that the sori and indusia; use high powerto observe the spores.Things to Remember
Know the life bicycle of the fern. Recognize specimens andslidesof the miscellaneous stages.Economic, Ecological, and Evolutionary Importance
Ferns and fern allies are primarily responsible for our moderndepositsof coal.
The fiddleheads that some varieties of ferns space edible.
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Ferns are essential for the florist, gardening and landscapeindustries.Consider This
Why room all this plants limited to wet habitats?
Which group of protists offered rise to this plants? (How carry out we know?)
Why is the epidermis of the horsetail for this reason rough? What does it needprotectionfrom?
All the the fern allies in this lab once towered 50-100 feet or more.What happened?
Links to Explore
Bryophyte taxonomy, images, and an ext at:
Get info around bryophytes from the Missouri botanical Garden at:
Lie down among the ferns in ~ the American Fern Society, try theirlengthylist of links:
Basic info on ferns and also fern allies, finish with images, courtesyof Texas A&M:
Look for ferns top top the "tree the life" at