Lab 8 - Primitive tree -Bryophytes,Ferns and also Fern Allies
As us pass indigenous mosses to ferns, we check out a gradual shift fromprimitiveto modern traits. There room two significant trends friend should emphasis on intoday"slab. The first is a change in life cycles, the 2nd is a changeinbasic inner structure.
You are watching: The sperm produced by mosses require _____ to reach an archegonium.
First, all tree undergo an alternation the generations,between a haploid gametophyte stage and a diploid sporophytestage. In the many primitive plants, favor mosses, the gametophyte isdominant(i.e. It"s large and green). In higher plants like ferns and fern allies,the sporophyte phase is dominant. Gametophytes produce gametes (spermandeggs) in a one-of-a-kind structure called a gametangium (-ia), whilesporophytesproduce spores in a one-of-a-kind structure referred to as a sporangium(-ia).
Second, every plants require to gain water to their cells.Primitivebryophyteslike mosses and liverworts room so little that they deserve to rely top top diffusionto move water in and also out that the plant. Mosses have actually a few strands ofwaterconducting tissue in their main stem, but nothing favor the huge andwell arranged network of tubes in tracheophytes, or "tubeplants".The vascular tissues in the much more advanced ferns and "fernallies"are made up of xylem and phloem, which command water,nutrients,and food throughout the tree body. We"ll look at this tissues in alaterlab.
Bryophytes likewise need a moist atmosphere to reproduce. Theirflagellatedsperm should swim v water to with the egg. So mosses andliverwortsare limited to moist habitats. There space no mosses in the desert.Butmosses space 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" dubbed gemmae,whichform in special tiny structures called gemmae cups.
Mosses and liverworts space lumped with each other as bryophytes,plantslacking true vascular tissues, and sharing a number of other primitivetraits. They also lack true stems, roots, or leaves, though they havecellsthat do these basic functions. The leafy green plant that us seewhen we look at a moss or a liverwort is yes, really the gametophyte,which is the dominant stage in all bryophytes. The sporophytesofbryophytes do 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 that Divisions
Division Bryophyta - (9,500 sp.) - mosses, Mnium, Sphagnum
Mosses come in two simple types, a cushiony type, through erect stalks,and a feather type, which forms flattened carpet of low-lying and also highlybranched moss plants. In both cases, the leafy environment-friendly gametophytes aredioeciousThey have the right to be masculine plants, v antheridia at the optimal of the plant, orfemaleplants, v archegonia in ~ the top. Remember that these gametophytesarealways haploid (1N) plants.
Sperm are produced within each antheridium, and also an egg ineacharchegonium.Because the plant is already haploid, this gametes deserve to be created bymitosis,simple cabinet division. The sperm swims to the archegonia v a thinfilm that water, drawn by a chemical attractant developed by the femaleplant,then swims down the neck of the archegonia to the egg. A an excellent morningdewis an ext than sufficient water for the sperm come swim. As soon as the spermentersthe archegonia, the fuses with the egg. The 2N zygote develops into adiploidsporophyte plant, a small stalk that grows directly out that the top ofthearchegonium. This stalk is at first green, and also photosynthetic, butlaterturns brown and becomes basically a parasite ~ above the femalegametophyte.
The sporophyte plant consists of a stalk, and also a small capsuleon the top. Within the capsule, cells undergo meiosis come producetetradsof haploid spores. Once the capsule is ripe, the hinged lid oroperculumopens up, and the spores room quickly distributed by wind and also water. Thesporesgerminate into a tiny eco-friendly thread, which looks like a an easy strand ofgreen algae. This similarity is one an ext clue that bryophytes aredescendedfrom eco-friendly algae. This at an early stage threadlike stage is dubbed the protonema(= an initial thread, plural = protonemata, choose stigma/stigmata). The newadultgametophytes prosper from a small bud that develops on the protonema.Eventuallythese gametophytes will grow to create gametes, and the entirety cyclewillstart end again. Mosses can additionally reproduce asexually by fragmentationor by growing small vegetative buds referred to as gemma, which have the right to break offand prosper into a new plant .
While bryophytes in basic are more interesting than important, inthe usual sense, a conspicuous exemption are mosses the the genus Sphagnum.Sphagnummoss forms thick mats which come to be compressed into peat, which can beusedas fuel, back it’s an extremely smoky. Peat also contains other plants suchas reeds, that flourish 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 for wounds. Whereas noodle absorbs 4-6timesits dry weight, dried sphagnum deserve to absorb 20 time its own weight influids!Peat bogs are very important and interesting ecosystems. Sphagnummosses considerably increase neighborhood acidity by publication H+ ions, and also the pHof peat bogs can drop come 4 or lower, probably the many acidic naturalenvironment.Peat bogs cover about 1% of the Earth’s soil surface, one area abouthalfthe dimension of the united States.
Division Hepaticophyta - (9,000 sp.), liverworts, Marchantia,Conocephalum, Porella
Liverworts have the most basic bodies of all the eco-friendly plants. Thegametophyte,the dominant stage, looks like a flat scaly leaf, with significant lobes.It look at for all the human being like a tiny flattened liver, therefore thescientificname hepatico-phyta = liver plant. During the middle Ages, thissimilaritycaused doctors to prescribe liverwort for illness of the liver.Accordingto the doctrine of Signatures the Creator had actually designed all of nature,includingplants, through our welfare in mind. People thought that plants had beenintentionally designed come resemble the offal of the human body they weresupposedto heal! hence liver-wort, wyrt being the Anglo-Saxon word for herb.Theshape the the liverwort to be the signature of the Creator in nature. Canyou guess: v what walnuts were claimed to cure ? (diseases the thebrain)
Liverworts re-superstructure the general properties of bryophytes, however are notveryclosely pertained to mosses or hornworts. Plenty of botanists think they mayhaveevolved independently, native a different group of green algae. Because that onething,liverworts don’t save food as starch yet as oils. If you get theaquaticliverwort Porella in lab, take a sniff that the jar, but not toodeep!It smells of rancid oils, oils that went a tiny funky while the plantwas being shipped. An additional characteristic unique to liverworts is theirlack that stomata, which are uncovered in all other plants, including mossesand hornworts.
In many varieties of liverworts, such as Marchantia, the oneyouwill most most likely see in lab, the antheridia and archegonia room not ontopof the plant, but hanging under from the underside of weird littlestructuresthat look choose tiny umbrellas. (These umbrella-shaped frameworks arecalledthe antheridiophore and archegoniophore). The bi-flagellated spermswimsto the egg, and also fertilization takes place to form a diploid (2N)zygote.The small diploid sporophytes, which stay attrached to the parentplant,have a very straightforward structure. Meiosis in ~ the sporophyte to produce anumber of haploid spores. These spores are surrounded by curious longandtwisted moist cells referred to as elaters. Once the capsule dries and also bursts,the elaters twist and also jerk roughly in a means that scatters the spores inall directions. Liverworts can also reproduce asexually by means ofspecialstructures referred to as gemmae cups. These small cups deserve to be easilyseenon the surface ar of the plant. Every gemma cup has a variety of tinyplantletscalled gemmae, and also a solitary drop that water will disperse them. Theselittlevegetative “clones” will then thrive into a brand-new gametophyte.
Division Anthocerophyta - (100 sp.), hornworts, Anthoceros
The eco-friendly gametophytes the the hornwort look very much choose aliverwort.But their small sporophytes much more closely resemble those of mosses. Thesporophytes prosper out the the gametophyte, and look like a small uprighthorn. Choose mosses, hornworts have actually stomata, and so are probably morecloselyrelated come mosses and also other plants than to the liverworts lock matresemble.These plants are symbiotic v the cyanobacteria Nostoc. Thecyanobacteriafixes nitrogen because that 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 of generations gametophyte gametangium (-ia) archegonium (-ia) antheridium (-ia) sporophyte sporangium (-ia) spore capsule protonema vascular system gemmae gemmae cupTo Do and also View
Examine the life mosses top top display. Notice the little capsuleson peak of the small sporophytes. Mosses generally thrive in among twogrowthtypes: cushiony moss and feathery moss.
Examine slides that the antheridia and archegonia. The sausageshaped antheridia develop sperm, and also the flask shaped archegoniaproduces eggs.
Examine slides the the moss capsule, and identify the spores.
Examine slides the the protonema. What type of algaedoesit repeat you of? This resemblance is additional evidence the greenalgaegave increase to all greater plants.
Examine the terrestrial liverworts Marchantia and also Conencephalum(oneor both should be on display). Exactly how does their expansion habit differ fromthat of the mosses? have the right to you see any kind of gemmae cups top top the uppersurfaceof these plants?
Examine slides the the liverwort Marchantia.
Examine the aquatic liverworts favor PorellaandRiccia(one or both have to be ~ above display). Notice how they differ from themoreterrestrial creates of liverwort.
Look at the maintained liverworts, and also observe their distinctreproductive frameworks (they watch like little green umbrellas). Howdoestheir life cycle differ from mosses?
Examine slides that the hornwort Anthocerophyta.Things come Remember
Know the life cycle of the moss in detail, and be may be torecognizethe various stages.
Hint: Be sure you understand the general life cycle ofplants,and can tell i beg your pardon stages space haploid gametophytes (1N) or diploidsporophytes(2N). We"ll discover several life cycles in lecture and in lab (moss,fern,pine, flowering plant), but every one of them are variations on the samebasictheme.Ecological, Evolutionary, and Economic Importance
Mosses are essential in landscaping and also gardening, specifically peatmoss(Sphagnum).
Peat moss (Sphagnum) has actually been offered historically together dressingsfor wounds.
Peat moss can be provided as fuel.
Mosses room the many primitive living land plants.
Hornworts contain symbiotic nests of the cyanobacteria Nostoc.
shining club moss
Introduction to Tracheophytes - Ferns and also Fern Allies
Tracheophytes (vascular plants) perfect the conquest of theearth’s surface started by the more primitive bryophytes. Just as theevolutionof spores to be the an essential to the intrusion of the land surface bybryophytes,the creation of complex vascular tissues let tracheophytes completetheconquest of dried land. Over there are about 250,000 types of vascularplants,grouped in nine divisions. Tracheophytes all have a fine developedroot-shootsystem, with highly devoted roots, stems, and leaves, andspecializedvasculartissue (xylem and phloem) that duty like miniature pipe toconductfood, water, and also nutrients transparent the plant. Due to the fact that ferns and fernallies posses true vascular tissues, castle can grow to be lot largerandthicker 보다 the bryophytes.
The ferns and fern allies (non-seed tracheophytes) note two majorevolutionarystrides. In these and in all much more advanced plants, the leafy environment-friendly diploidsporophyte currently becomes the leading stage. The small gametophytemay be either autotropophic (like the fern prothallus) orheterotrophic(like the gametophytes of some lycopsids), and also is generally totally free livingand elevation of the parental sporophyte. Unlike the vascularsporophytes,the gametophytes have actually no vascular tissue at all. These gametophytes aretherefore really small, and develop ideal in moist areas, wherein they canabsorbwater straight from your surroundings.
Like the bryophytes, ferns and also fern allies room still limited tomoisthabitats. Their flagellated sperm need a slim film of water come swimbetweenthe antheridium and the archegonium. And also when the infant sporophyte growsup from the gametophyte, that is exposed come desiccation (drying up). Thisbasic strategy that a free-swimming sperm and a non-motile egg is sharedby plants, animals, and also algae. It renders sense, since it method onlyoneset that gametes needs to make the perilous journey exterior of theorganism.
ground pine tree (Lycopodium) reflecting strobili
The ferns and fern allies germinate indigenous spores. These plants aremostlyhomosporous- their spores room identical and you can"t distinguish which willgrow into male or mrs plants. Lock are additionally monoecious -boththe archegonia and also antheridia (male and female reproductive structures)are borne top top the exact same plant. Comparison these primitive vascular plantswiththe more advanced particle plants, the gymnosperms and also angiosperms, whichgerminatefrom seeds quite than indigenous spores. Seed plants are all heterosporous.It is basic to identify the larger female megaspore fromthesmaller male microspore. The sperm of seed plants have noflagella.They absence antheridia, and only a few still have actually an archegonia. Unlikethemore primitive ferns and also fern allies, seed plants are mainly dioecious,having separate male and also female plants.
In countless of these primitive plants, specific leaves are specializedforreproduction. This modified leaves, or sporophylls, be affected by each other thesporangiaat their bases. This sporophylls usually branch out from a shortenedstem,forming a club shaped structure dubbed a strobilus. The pineconeand the flower are intricate variations on this primitive strobili.
There space four departments of non-seed tracheophytes, vascular plantsthat blee by way of spores, the Psilophyta, Lycophyta,Sphenophyta,and Pterophyta. Before these non-seed tracheophytes evolved, thebryophyteswere the dominant type of tree life. The evolution 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 various other club mosses cultivation in the the shade of a large pine tree,thinkfor a moment around how these tiny plants were as soon as the masters of theplanet,forming vast forests v trunks from 20 to 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= little wing)Terms homosporous heterosporous megaspores microspores rhizomes sporophylls strobilus (-i) sori indusium (-ia) prothallus fiddleheadsCharacteristics the Divisions
Division Psilophyta - (fr Gr. Psilo = smooth), whiskferns,Psilotum
There are only two life genera that whisk ferns, single survivors that alarge and widespread team of beforehand land plants. In addition to thelivingDivision Psilophyta, the psilopsids, there are two extinct divisions ofprimeval vascular plants. The primitive whisk ferns resemble theseextinctpioneers in many ways. They space the just living vascular plants thatlacka root-shoot system, a characteristic castle share with both extinctDivisionsof genealogical vascular plants. Some current molecular proof suggeststhatone, or even both, the the living genera of psilopsids might actually bemoreclosely pertained to 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 uncovered in tropical and subtropical areas, and also occursthroughoutthe southern US. Ns once uncovered one growing on my ago porch under theleavesof a spider plant. Whisk ferns space a typical weed in greenhouses alloverthe world. They are basic green upright stems, with dichotomousbranching.They have no leaves, and no true roots. The external tissues the 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 tree around. Roots thrive out the bottom the therhizome,and a new plant have the right to arise in ~ the same point from the top.
The environment-friendly stem-like plant is the diploid sporophyte, the dominantstagein the life cycle. In the tiny sporangia (bright yellow) the formalongthe upper stems, the spore mother cell develops haploid spores through meiosis.Their gametophytes are tiny little thread-like underground plants thatlack chlorophyll, and live together heterotrophs in the soil, looking andactingmuch prefer a tiny fungi. That actually consists of a symbiotic fungi, thesamemycorrhizae the live in the rhizomes the the adult sporophyte.
Division Lycophyta - (1,000 sp., fr. Gr. Lycos=wolf), clubmosses,quillworts, Lycopodium (podus=foot)
Their room only 5 living genera the lycopsids, but at once fromthe remote Devonian, around 400 mya, well right into the Carboniferous, theywere the dominant form of vegetation top top the face of the Earth. Currently theyare lessened to a zero of their glorious past, inconspicuous littleplantsin the woodland understory. The tropical varieties are tiny epiphytes(plantsthat thrive on various other plants).
Their roots flourish from unique underground stems called rhizomes, asdo many of this primitive tracheophytes. In some types thesporophyllsare mixed in through the scale-like leaves. In plenty of species, thesporophyllsare organized into strobili, hence the usual name the “club moss”. Thesperm swim under the strobilus to the archegonia, and the zygote thatformsis retained in the cone, i beg your pardon ripens and falls come the ground. Thegametophytesare independent and free-living, They room curious creatures that lookandact nothing favor their sporophyte parents. They can be eitherheterotrophicor autotrophic, and also usually have a symbiotic fungi linked withthem.Many the the lycopsids are heterosporous. Selaginella is a goodexampleof a heterosporous plant.
Division Sphenophyta - (15 sp., one genus, fr. Gr.sphen=wedge),horsetails, Equisitum
In rubbish places, disturbed areas like trails and railroad beds, andin weird corners of fields and forests you can find another little plantquietly dreaming that its previous splendor, the horsetail. Horsetailsappearedin the so late Devonian, and were among the leading forest trees forhundredsof countless years. Just one genus the Sphenophyta tho exists, thegenusEquisetum,and it might be the earliest living genus of plants on earth. Horsetailstoweredamong the Carboniferous forests, getting to heights of 30-60 feet. Muchofthe charcoal deposits we make use of for fuel now were formed from horsetailsand various other trees during the Carboniferous, toward the finish of thePaleozoic.
Horsetails have actually true roots, stems, and also leaves, though the leaves arelittle more than flattened stems. Your hollow, ribbed stems arejointed,kind of prefer a stalk the bamboo, and also a whorl of pipeline arises in ~ eachjoint.The plants are spread vegetatively by rhizomes. The stems feeling veryrough,because the epidermal tissues room impregnated v tiny seed ofsilica(sand). This probably helps protect the plant against herbivores. Theserough stems make this plant ideal for pioneer women to usage forscrubbingpots and pans, hence its other common name, “scouring rush”.
The green plant we see is the diploid sporophyte generation. Thestalkscan be very branched vegetative stalks, which actually look likehorsetails, or straight unbranched reproductive stalks, which space tippedwitha big strobilus include the sporangia. The homosporous sporesdevelopinto a teeny-tiny eco-friendly gametophyte, just 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 advanced from the psilopsids, at some time in theDevonian,relatively at an early stage in land tree evolution. They are really abundant anddiverse, varying in size from a single centimeter to tree 24 meterstallwith 5 meter fronds. Ferns have actually been much better competitors v seedplantsthan other seedless vascular plants, and are a conspicuous part of thelandscape transparent the world, yet especially in the tropics, where75%of their 12,000 types occur.
Ferns are reasonably advanced plants, through true roots, stems andleaves.The tongue of the fern is dubbed a frond, and also the small individualleafletsare referred to as pinnae. Ferns have true leaves, what botanists callmacrophylls.While the pipeline of much more primitive plants, which space calledmicrophylls,are simply extensions of the epidermis of the stem, the leaves of fernsand higher plants were formed as a net of tissue extended betweensmallterminal branches. The leaves of higher plants, and also the modifiedleaves that make up the pine cone and also the flower.
The life bicycle of the fern is typical of other non-seed vascularplants.The leafy eco-friendly plant is the sporophyte. Productive fronds developsclustersof small sporangia top top the underside the the frond. These clusters ofsporangiaare referred to as sori (sing. Sorus). Sori are often defended by atinyumbrella-like cap called an indusium (-ia). Ferns room mostlyhomosporous,though some space heterosporous. The heterosporous state is a moreadvancedcondition, that appears to have evolved independently in number of groupsofplants.
The haploid spores are formed by meiosis inside the sporangium. Theyare ejected in a miniature explosion brought about by the unequal dry ofthealternate thick and thin-walled cells that line the external surface. Thetop traction slowly back until it reaches a an essential point and also then snapsforward at an tremendous speed. At that dimension scale, the expulsion offernspores is among the many explosive events in nature. The sporesgerminateinto small gametophytes. The small heart shame gametophyte is called aprothallus,literally “first-body” (pl prothalli). The prothallus has actually no vasculartissue.Its small size allows it rely completely on diffusion. Its small rhizoidsareassociated through mycorrhizal fungi. The small prothallus is green, andphotosynthetic, and bears one of two people antheridia and archegonia, orsometimesboth together, top top its upper surface (lab slides have actually both top top sameprothallus).The archegonia are constantly found in ~ the arch the the heart, and theantheridiaare tucked away among the tiny rhizoids in ~ the other end. The spermswimsto the egg come fuse right into a diploid zygote. The brand-new sporophyte growsdirectlyout the the peak of the gametophyte. When it an initial begins come uncurl, thefrond looks prefer the scrolled neck of a violin or fiddle, and also thisstageof breakthrough is referred to as a fiddlehead.
To Do and View
Examine the life lycopsids top top display. Why space they calledclub mosses? notice that quillworts and also Selaginella space verydifferentin appearance native the club mosses.
Examine slides that Selaginella"s strobilus. Recognize megasporesand microspores.
Examine the living horsetails ~ above display. Notice theprominentstrobiliofthe reproductive stalks, and also the bushy growth kind of the vegetativestalks(if available).
Examine the life whisk ferns top top display. Psilopsidshave a simple dichotomous branching pattern. You might see tiny yellowsporangiaon the branches. Whisk ferns absence strobili. These primitive plants areclosely related to ferns.
Examine the life ferns ~ above display. Have the right to you see any type of fiddleheads?Look because that the rhizomes. Rhizomes are modified horizontal stemsbearingroots, that operation along or just underneath the ground, and spread fernsandfern allies around.
Examine the living fern prothallus on screen under adissectingmicroscope. Keep in mind its characteristic heart shape. Part prothalli mayhavea tiny brand-new fern emerging from the notch the the "arch" heart, whereby thearchegoniaarelocated.
Examine slides that the prothallus: find the archegonia(can you watch an egg?).
Examine the fern leaflet on screen under the dissectingmicroscope.Notice the influential indusia, and the small sporangiapeekingout indigenous beneath. You"ll see a couple of groups of sporangia that have losttheirindusium. If you"re lucky, as the warm of the microscope dries out theleaflet, you might see the sporangia eject that is spores. However don"tblink- it"s among the fastest and also most explosive acts in nature. Usage highpowerto watch the spores.
Examine slides of the sori and indusia; usage high powerto watch the spores.Things come Remember
Know the life bicycle of the fern. Identify specimens andslidesof the various stages.Economic, Ecological, and also Evolutionary Importance
Ferns and also fern allies are mostly responsible because that our moderndepositsof coal.
The fiddleheads the some species of ferns are edible.
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Ferns are important for the florist, gardening and also landscapeindustries.Consider This
Why room all this plants minimal to wet habitats?
Which group of protists gave rise to this plants? (How carry out we know?)
Why is the epidermis that the horsetail therefore rough? What does the needprotectionfrom?
All of the fern allies in this lab when towered 50-100 feet or more.What happened?
Links come Explore
Bryophyte taxonomy, images, and an ext at:
Get info around bryophytes indigenous the Missouri factory Garden at:
Lie down among the ferns at the American Fern Society, try theirlengthylist the links:
Basic details on ferns and fern allies, finish with images, courtesyof Texas A&M:
Look because that ferns on the "tree of life" at