Lab 8 - Primitive tree -Bryophytes,Ferns and also Fern Allies
As we pass native mosses to ferns, we watch a gradual shift fromprimitiveto modern-day traits. There room two significant trends you should emphasis on intoday"slab. The an initial is a transition in life cycles, the second is a changeinbasic internal structure.
You are watching: The sporophyte is much larger than the gametophyte in
First, all plants undergo an alternation of generations,between a haploid gametophyte stage and also a diploid sporophytestage. In the many primitive plants, like mosses, the gametophyte isdominant(i.e. It"s large and green). In higher plants like ferns and also fern allies,the sporophyte stage is dominant. Gametophytes develop gametes (spermandeggs) in a distinct structure dubbed a gametangium (-ia), whilesporophytesproduce spores in a special structure referred to as a sporangium(-ia).
Second, all plants need to obtain water to your cells.Primitivebryophyteslike mosses and also liverworts space so tiny that they can rely top top diffusionto move water in and also out the the plant. Mosses have actually a couple of strands ofwaterconducting tissue in their central stem, however nothing prefer the huge andwell arranged network of tubes in tracheophytes, or "tubeplants".The vascular organization in the much more advanced ferns and "fernallies"are consisted of of xylem and phloem, which command water,nutrients,and food throughout the tree body. We"ll look at this tissues in alaterlab.
Bryophytes additionally need a moist environment to reproduce. Theirflagellatedsperm must swim v water to with the egg. For this reason mosses andliverwortsare limited to moist habitats. There space no mosses in the desert.Butmosses room surprisingly resistant to drying up, and can survive underveryharsh conditions. Mosses space the most abundant tree in both theArcticand the Antarctic. Asexual reproduction in bryophytes is accomplishedbyfragmentation or by small vegetative "sprouts" referred to as 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, despite they havecellsthat execute these basic functions. The leafy green plant that us seewhen us look in ~ a moss or a liverwort is yes, really the gametophyte,which is the leading stage in every bryophytes. The sporophytesofbryophytes do not have actually a free-living existence. Castle grow straight outof the fertilized egg in the archegonia, and also remain dependent on theparentgametophyte for your nutrition.Characteristics the Divisions
Division Bryophyta - (9,500 sp.) - mosses, Mnium, Sphagnum
Mosses come in two an easy types, a cushiony type, through erect stalks,and a feathery type, which forms flattened carpet of low-lying and highlybranched moss plants. In both cases, the leafy environment-friendly gametophytes aredioeciousThey can be male plants, through antheridia at the height of the plant, orfemaleplants, through archegonia in ~ the top. Remember that these gametophytesarealways haploid (1N) plants.
Sperm are created within each antheridium, and an egg ineacharchegonium.Because the tree is already haploid, these gametes deserve to be created bymitosis,simple cabinet division. The sperm swims to the archegonia v a thinfilm the water, attracted by a chemistry attractant developed by the femaleplant,then swims under the neck that the archegonia to the egg. A great morningdewis an ext than enough water for the sperm come swim. When the spermentersthe archegonia, that fuses v the egg. The 2N zygote creates into adiploidsporophyte plant, a tiny stalk the grows straight out of the optimal ofthearchegonium. This stalk is originally green, and photosynthetic, butlaterturns brown and also becomes basically a parasite top top the femalegametophyte.
The sporophyte plant is composed of a stalk, and a little capsuleon the top. In ~ the capsule, cell undergo meiosis come producetetradsof haploid spores. When the capsule is ripe, the hinged lid oroperculumopens up, and also the spores space quickly spread by wind and water. Thesporesgerminate right into a tiny environment-friendly thread, i beg your pardon looks choose a straightforward strand ofgreen algae. This similarity is one an ext clue the bryophytes aredescendedfrom environment-friendly algae. This at an early stage threadlike phase is referred to as the protonema(= an initial thread, many = protonemata, prefer stigma/stigmata). The newadultgametophytes thrive from a tiny bud that develops on the protonema.Eventuallythese gametophytes will grow to develop gametes, and the entirety cyclewillstart end again. Mosses can also reproduce asexually by fragmentationor by growing little vegetative buds dubbed gemma, which have the right to break offand thrive into a brand-new plant .
While bryophytes in basic are more interesting than important, inthe normal sense, a conspicuous exemption are mosses the the genus Sphagnum.Sphagnummoss forms dense mats which become compressed right into peat, which can beusedas fuel, although it’s really smoky. Peat likewise contains various other plants suchas reeds, that flourish amid the sphagnum. In dried form, peat moss isremarkablyabsorbent and, and also has been provided 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 really important and also interesting ecosystems. Sphagnummosses substantially increase neighborhood acidity by releasing H+ ions, and the pHof peat bogs can drop come 4 or lower, probably the many acidic naturalenvironment.Peat bogs cover around 1% that the Earth’s land surface, an area abouthalfthe size of the unified States.
Division Hepaticophyta - (9,000 sp.), liverworts, Marchantia,Conocephalum, Porella
Liverworts have actually the simplest bodies of every the eco-friendly plants. Thegametophyte,the dominant stage, looks favor a flat scaly leaf, with significant lobes.It watch for every the civilization like a tiny flattened liver, hence thescientificname hepatico-phyta = liver plant. During the middle Ages, thissimilaritycaused physicians to prescribe liverwort for conditions of the liver.Accordingto the doctrine of Signatures the Creator had actually designed every one of nature,includingplants, v our welfare in mind. People thought that plants had actually beenintentionally designed come resemble the organs of the human body they weresupposedto heal! therefore liver-wort, wyrt being the Anglo-Saxon word for herb.Theshape that the liverwort to be the signature that the Creator in nature. Canyou guess what walnuts were claimed to cure ? (diseases the thebrain)
Liverworts re-publishing the general properties that bryophytes, however are notveryclosely pertained to mosses or hornworts. Many botanists think castle mayhaveevolved independently, native a different group of eco-friendly algae. Because that onething,liverworts don’t save food as starch but as oils. If you acquire theaquaticliverwort Porella in lab, take it a sniff the the jar, yet not toodeep!It smells that rancid oils, oils the went a tiny funky while the plantwas being shipped. One more characteristic distinctive to liverworts is theirlack the stomata, which are uncovered in all other plants, including mossesand hornworts.
In many varieties of liverworts, such together Marchantia, the oneyouwill most likely see in lab, the antheridia and also archegonia are not ontopof the plant, yet 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 fertilization takes location to form a diploid (2N)zygote.The tiny diploid sporophytes, which stay attrached to the parentplant,have a very an easy structure. Meiosis within the sporophyte to produce anumber of haploid spores. These spores space surrounded by curious longandtwisted moist cells dubbed elaters. As soon as the capsule dries and bursts,the elaters twist and also jerk roughly in a means that scatters the spores inall directions. Liverworts can likewise reproduce asexually by method ofspecialstructures called gemmae cups. These tiny cups have the right to be easilyseenon the surface of the plant. Each gemma cup contains a variety of tinyplantletscalled gemmae, and a single drop of water will certainly disperse them. Theselittlevegetative “clones” will certainly then grow into a new gametophyte.
Division Anthocerophyta - (100 sp.), hornworts, Anthoceros
The eco-friendly gametophytes the the hornwort look an extremely much prefer aliverwort.But their little sporophytes much more closely resemble those the mosses. Thesporophytes grow out the the gametophyte, and look like a small uprighthorn. Like mosses, hornworts have actually stomata, and also so are most likely morecloselyrelated to mosses and other plants than to the liverworts they matresemble.These plants space 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 system gemmae gemmae cupTo Do and also View
Examine the life mosses top top display. Notification the little capsuleson height of the tiny sporophytes. Mosses generally grow in among twogrowthtypes: cushiony moss and also feathery moss.
Examine slides of the antheridia and also archegonia. The sausageshaped antheridia produce sperm, and also the flask shame archegoniaproduces eggs.
Examine slides that the moss capsule, and identify the spores.
Examine slides that the protonema. What type of algaedoesit remind you of? This same is additional evidence that greenalgaegave climb to all greater plants.
Examine the terrestrial liverworts Marchantia and also Conencephalum(oneor both should be top top display). Just how does their growth habit different fromthat of the mosses? deserve to you see any kind of gemmae cups top top the uppersurfaceof this plants?
Examine slides the the liverwort Marchantia.
Examine the aquatic liverworts prefer PorellaandRiccia(one or both need to be top top display). Notice how they different from themoreterrestrial creates of liverwort.
Look in ~ the maintained liverworts, and also observe their distinctreproductive frameworks (they watch like little green umbrellas). Howdoestheir life cycle differ from mosses?
Examine slides the the hornwort Anthocerophyta.Things come Remember
Know the life bicycle of the moss in detail, and be may be torecognizethe various stages.
Hint: Be sure you recognize the basic life bike ofplants,and have the right to tell i beg your pardon stages room haploid gametophytes (1N) or diploidsporophytes(2N). We"ll find out several life cycles in lecture and also in lab (moss,fern,pine, flowering plant), but all of them space variations on the samebasictheme.Ecological, Evolutionary, and Economic Importance
Mosses are important in landscaping and gardening, particularly peatmoss(Sphagnum).
Peat moss (Sphagnum) has been supplied historically as dressingsfor wounds.
Peat moss have the right to be offered as fuel.
Mosses space the most primitive living land plants.
Hornworts contain symbiotic swarms of the cyanobacteria Nostoc.
shining society moss
Introduction come Tracheophytes - Ferns and also 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 an essential to the invasion of the land surface bybryophytes,the development of complicated vascular tissues let tracheophytes completetheconquest of dry land. Over there are around 250,000 species of vascularplants,grouped in nine divisions. Tracheophytes all have a well developedroot-shootsystem, v highly committed roots, stems, and leaves, andspecializedvasculartissue (xylem and phloem) that function like miniature pipe toconductfood, water, and nutrients transparent the plant. Since ferns and fernallies posses true vascular tissues, castle can prosper to be much largerandthicker than the bryophytes.
The ferns and fern allies (non-seed tracheophytes) note two majorevolutionarystrides. In these and also in all an ext advanced plants, the leafy eco-friendly diploidsporophyte now becomes the dominant stage. The small gametophytemay be either autotropophic (like the fern prothallus) orheterotrophic(like the gametophytes of part lycopsids), and also is generally complimentary livingand elevation of the parental sporophyte. Unequal the vascularsporophytes,the gametophytes have actually no vascular tissue at all. These gametophytes aretherefore really small, and develop best in moist areas, whereby they canabsorbwater directly from their surroundings.
Like the bryophytes, ferns and fern allies space still restricted tomoisthabitats. Their flagellated sperm need a thin film that water come swimbetweenthe antheridium and also the archegonium. And also when the baby sporophyte growsup indigenous the gametophyte, it is exposed to desiccation (drying up). Thisbasic strategy that a free-swimming sperm and a non-motile egg is sharedby plants, animals, and algae. It makes sense, because it method onlyoneset of gametes needs to make the perilous journey outside of theorganism.
ground pine (Lycopodium) mirroring strobili
The ferns and also fern allies germinate native spores. These plants aremostlyhomosporous- your spores space identical and also you can"t distinguish which willgrow into male or mrs plants. They are likewise monoecious -boththe archegonia and also antheridia (male and female reproductive structures)are borne ~ above the very same plant. Comparison these primitive vascular plantswiththe more advanced particle plants, the gymnosperms and also angiosperms, whichgerminatefrom seeds quite than indigenous spores. Seed plants space all heterosporous.It is simple to differentiate the bigger female megaspore fromthesmaller masculine microspore. The sperm of particle plants have actually noflagella.They lack antheridia, and only a couple of still have actually an archegonia. Unlikethemore primitive ferns and fern allies, seed plants are largely dioecious,having separate male and also female plants.
In plenty of of this primitive plants, certain leaves room specializedforreproduction. This modified leaves, or sporophylls, be afflicted with thesporangiaat their bases. This sporophylls commonly branch the end from a shortenedstem,forming a club shaped structure referred to as a strobilus. The pineconeand the flower are fancy variations on this primitive strobili.
There are four divisions of non-seed tracheophytes, vascular plantsthat give birth by method of spores, the Psilophyta, Lycophyta,Sphenophyta,and Pterophyta. Prior to these non-seed tracheophytes evolved, thebryophyteswere the dominant form of tree life. The evolutionary edge of having amore efficient conducting system, and a well-developed root-shootsystemenabled them to outcompete bryophytes. If you’re lucky enough to seegroundpine or various other club mosses growing in the shade of a large pine tree,thinkfor a moment about how these tiny plants were once the master of theplanet,forming large forests v trunks native 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= little wing)Terms homosporous heterosporous megaspores microspores rhizomes sporophylls strobilus (-i) sori indusium (-ia) prothallus fiddleheadsCharacteristics that Divisions
Division Psilophyta - (fr Gr. Psilo = smooth), whiskferns,Psilotum
There are just two life genera the whisk ferns, sole survivors of alarge and widespread group of early land plants. In enhancement to thelivingDivision Psilophyta, the psilopsids, there room two extinct departments ofprimeval vascular plants. The primitive whisk ferns resemble theseextinctpioneers in numerous ways. They are the only living vascular tree thatlacka root-shoot system, a characteristic they share v both extinctDivisionsof ancestral vascular plants. Some recent molecular evidence suggeststhatone, or also both, the the living genera the psilopsids might actually bemoreclosely concerned ferns, favor a fern that has actually reverted come moreprimitivetraits. If this is true, then Psilophyta will sign up with the ranking of thenumerousextinct departments of plants.
Psilopsids are discovered in tropical and also subtropical areas, and occursthroughoutthe southern US. Ns once uncovered one growing on my back porch under theleavesof a spider plant. Whisk ferns space a usual weed in greenhouses alloverthe world. Castle are an easy green upright stems, v dichotomousbranching.They have actually no leaves, and no true roots. The external tissues the the stemdoall the photosynthesizing. A portion of the stem referred to as a rhizome runsalong the ground, or just below it. A rhizome is a horizontalstemthat spreads the tree around. Roots grow out the bottom of therhizome,and a new plant have the right to arise in ~ the same point from the top.
The green stem-like plant is the diploid sporophyte, the dominantstagein the life cycle. In the tiny sporangia (bright yellow) that formalongthe upper stems, the spore mommy cell creates haploid spores by meiosis.Their gametophytes are tiny small thread-like underground tree thatlack chlorophyll, and live together heterotrophs in the soil, spring andactingmuch favor a small fungi. It actually contains a symbiotic fungi, thesamemycorrhizae that live in the rhizomes of the adult sporophyte.
Division Lycophyta - (1,000 sp., fr. Gr. Lycos=wolf), clubmosses,quillworts, Lycopodium (podus=foot)
Their are only 5 living genera of lycopsids, but at one time fromthe far-off Devonian, around 400 mya, well right into the Carboniferous, theywere the dominant form of vegetation ~ above the confront of the Earth. Now theyare lessened to a zero of their glorious past, inconspicuous littleplantsin the forest understory. The tropical species are tiny epiphytes(plantsthat flourish on other plants).
Their roots prosper from distinct underground stems dubbed rhizomes, asdo most of this primitive tracheophytes. In some types thesporophyllsare combined in through the scale-like leaves. In countless species, thesporophyllsare organized into strobili, thus the usual name the “club moss”. Thesperm swim under the strobilus come the archegonia, and also the zygote thatformsis retained in the cone, which ripens and also falls come the ground. Thegametophytesare independent and also free-living, They space curious creatures that lookandact nothing choose their sporophyte parents. They deserve to be eitherheterotrophicor autotrophic, and usually have a symbiotic fungi associated withthem.Many that the lycopsids space heterosporous. Selaginella is a goodexampleof a heterosporous plant.
Division Sphenophyta - (15 sp., one genus, fr. Gr.sphen=wedge),horsetails, Equisitum
In rubbish places, disturbed locations like trails and also railroad beds, andin odd corners of fields and also forests you can find another little plantquietly dreaming the its previous splendor, the horsetail. Horsetailsappearedin the late Devonian, and also were among the leading forest tree forhundredsof countless years. Only one genus that Sphenophyta still 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 coal deposits we manipulate for fuel now were created from horsetailsand various other trees during the Carboniferous, toward the end of thePaleozoic.
Horsetails have actually true roots, stems, and leaves, despite the pipeline arelittle an ext than flattened stems. Their hollow, ribbed stems arejointed,kind of prefer a stalk that bamboo, and a whorl of leaves arises at eachjoint.The plants space spread vegetatively by rhizomes. The stems feeling veryrough,because the epidermal tissues are impregnated through tiny seed ofsilica(sand). This most likely helps safeguard the plant against herbivores. Theserough stems make this plant right for pioneer ladies to use forscrubbingpots and pans, therefore its other typical name, “scouring rush”.
The eco-friendly plant we check out is the diploid sporophyte generation. Thestalkscan be extremely branched vegetative stalks, which actually look likehorsetails, or directly unbranched reproductive stalks, which are tippedwitha large strobilus comprise the sporangia. The homosporous sporesdevelopinto a teeny-tiny green gametophyte, just a few mm long, that lookslikethe gametophyte the a fern. The gametophyte is haploid, free-living, andautotrophic.
Division Pterophyta - (12,000 sp., fr. Gr. Pteridion=littlewing),ferns
Ferns probably progressed from the psilopsids, at some time in theDevonian,relatively early on in land tree evolution. Lock are an extremely abundant anddiverse, ranging in size from a solitary centimeter to tree 24 meterstallwith 5 meter fronds. Ferns have actually been better competitors with seedplantsthan 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, with true roots, tribe andleaves.The blade of the fern is referred to as a frond, and also the little individualleafletsare referred to as pinnae. Ferns have actually true leaves, what botanists callmacrophylls.While the pipeline of much more primitive plants, which are calledmicrophylls,are simply extensions of the epidermis the the stem, the pipeline of fernsand greater plants were created as a internet of tissue stretched betweensmallterminal branches. The pipeline of greater plants, and also the modifiedleaves that consist of the pine cone and also the flower.
The life cycle of the fern is typical of various other non-seed vascularplants.The leafy green plant is the sporophyte. Abundant fronds developsclustersof little sporangia top top the underside the the frond. These clusters ofsporangiaare dubbed sori (sing. Sorus). Sori room often protected 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 developed independently in number of groupsofplants.
The haploid spores are created by meiosis within the sporangium. She ejected in a miniature explosion brought about by the unequal drying ofthealternate thick and also thin-walled cells that line the external surface. Thetop traction slowly earlier until that reaches a an essential point and also then snapsforward in ~ an remarkable speed. In ~ that size scale, the expulsion offernspores is among the most explosive occasions in nature. The sporesgerminateinto tiny gametophytes. The small heart shame gametophyte is called aprothallus,literally “first-body” (pl prothalli). The prothallus has actually no vasculartissue.Its tiny size lets it rely completely on diffusion. Its tiny rhizoidsareassociated through mycorrhizal fungi. The small prothallus is green, andphotosynthetic, and bears one of two people antheridia and also archegonia, orsometimesboth together, top top its upper surface (lab slides have both on 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 to fuse right into a diploid zygote. The new sporophyte growsdirectlyout the the top of the gametophyte. As soon as it first begins to uncurl, thefrond looks like the scrolled neck of a violin or fiddle, and also thisstageof breakthrough is called a fiddlehead.
To Do and also View
Examine the life lycopsids top top display. Why are they calledclub mosses? an alert that quillworts and also Selaginella room verydifferentin appearance native the society mosses.
Examine slides the Selaginella"s strobilus. Identify megasporesand microspores.
Examine the living horsetails top top display. Notice theprominentstrobiliofthe reproductive stalks, and the bushy growth form of the vegetativestalks(if available).
Examine the life whisk ferns top top display. Psilopsidshave a straightforward dichotomous branching pattern. You may see small yellowsporangiaon the branches. Whisk ferns lack strobili. These primitive plants areclosely regarded ferns.
Examine the life ferns ~ above display. Can you see any type of fiddleheads?Look for the rhizomes. Rhizomes space modified horizontal stemsbearingroots, that operation along or just underneath the ground, and also spread fernsandfern allies around.
Examine the life fern prothallus on display screen under adissectingmicroscope. Keep in mind its characteristic love shape. Part prothalli mayhavea tiny brand-new fern emerging from the notch the the "arch" heart, where thearchegoniaarelocated.
Examine slides the the prothallus: discover the archegonia(can you view an egg?).
Examine the fern leaflet on screen under the dissectingmicroscope.Notice the significant indusia, and the tiny sporangiapeekingout indigenous beneath. You"ll watch a couple of groups that sporangia that have actually losttheirindusium. If you"re lucky, as the warm of the microscopic lense dries out theleaflet, you can see the sporangia eject the spores. But don"tblink- it"s one of the fastest and also most explosive acts in nature. Usage highpowerto observe the spores.
Examine slides the the sori and indusia; usage high powerto watch the spores.Things come Remember
Know the life cycle of the fern. Recognize specimens andslidesof the various stages.Economic, Ecological, and also Evolutionary Importance
Ferns and fern allies are mainly responsible because that our moderndepositsof coal.
The fiddleheads that some varieties of ferns are edible.
See more: How Long Does Salami Last After Opening, How Long Does Opened Dry Salami Last
Ferns are crucial for the florist, gardening and landscapeindustries.Consider This
Why are all these plants restricted to wet habitats?
Which team of protists offered rise to this plants? (How carry out we know?)
Why is the epidermis the the horsetail for this reason rough? What does it needprotectionfrom?
All that 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 about bryophytes from the Missouri factory Garden at:
Lie down amongst the ferns at the American Fern Society, try theirlengthylist the links:
Basic information on ferns and also fern allies, finish with images, courtesyof Texas A&M:
Look for ferns top top the "tree the life" at