Lab 8 - Primitive plants -Bryophytes,Ferns and also Fern Allies
As us pass from mosses come ferns, we view a gradual shift fromprimitiveto modern-day traits. There are two significant trends friend should focus on intoday"slab. The very first is a change in life cycles, the 2nd is a changeinbasic interior structure.
You are watching: Why must ferns live in moist environments
First, all plants undergo an alternation that generations,between a haploid gametophyte stage and a diploid sporophytestage. In the many primitive plants, prefer mosses, the gametophyte isdominant(i.e. It"s big and green). In greater plants favor ferns and also fern allies,the sporophyte phase is dominant. Gametophytes develop gametes (spermandeggs) in a unique structure dubbed a gametangium (-ia), whilesporophytesproduce spores in a special structure dubbed a sporangium(-ia).
Second, all plants require to get water to your cells.Primitivebryophyteslike mosses and liverworts room so little that they can rely on diffusionto move water in and out the the plant. Mosses have actually a few strands ofwaterconducting organization in their main stem, but nothing like the huge andwell arranged network of pipe in tracheophytes, or "tubeplants".The vascular organization in the more advanced ferns and also "fernallies"are consisted of of xylem and also phloem, which command water,nutrients,and food transparent the tree body. We"ll look at these tissues in alaterlab.
Bryophytes likewise need a moist atmosphere to reproduce. Theirflagellatedsperm must swim v water to with the egg. Therefore mosses andliverwortsare minimal to moist habitats. There space no mosses in the desert.Butmosses are surprisingly resistant to drying up, and also can endure underveryharsh conditions. Mosses are the many abundant tree in both theArcticand the Antarctic. Asexual reproduction in bryophytes is accomplishedbyfragmentation or by small vegetative "sprouts" called gemmae,whichform in special little structures referred to as gemmae cups.
Mosses and also liverworts are lumped together as bryophytes,plantslacking true vascular tissues, and also sharing a variety of other primitivetraits. They also lack true stems, roots, or leaves, despite they havecellsthat perform these general functions. The leafy green plant that we seewhen us look in ~ a moss or a liverwort is yes, really the gametophyte,which is the dominant stage in every bryophytes. The sporophytesofbryophytes execute not have actually a free-living existence. They grow directly outof the fertilized egg in the archegonia, and also remain dependence on theparentgametophyte for their nutrition.Characteristics the Divisions
Division Bryophyta - (9,500 sp.) - mosses, Mnium, Sphagnum
Mosses come in two basic types, a cushiony type, with erect stalks,and a feathery type, which develops flattened mats of low-lying and highlybranched moss plants. In both cases, the leafy eco-friendly gametophytes aredioeciousThey have the right to be male plants, through antheridia in ~ the top of the plant, orfemaleplants, through archegonia at the top. Remember that these gametophytesarealways haploid (1N) plants.
Sperm are developed within each antheridium, and an egg ineacharchegonium.Because the tree is currently haploid, these gametes have the right to be created bymitosis,simple cell division. The sperm swims come the archegonia v a thinfilm that water, attracted by a chemical attractant created by the femaleplant,then swims down the neck the the archegonia come the egg. A an excellent morningdewis much more than adequate water for the sperm to swim. When the spermentersthe archegonia, it fuses v the egg. The 2N zygote creates into adiploidsporophyte plant, a small stalk the grows straight out of the top ofthearchegonium. This stalk is originally green, and photosynthetic, butlaterturns brown and also becomes essentially a parasite ~ above the femalegametophyte.
The sporophyte plant consists of a stalk, and a little capsuleon the top. Within the capsule, cells undergo meiosis come producetetradsof haploid spores. As soon as the capsule is ripe, the hinged lid oroperculumopens up, and the spores room quickly dispersed by wind and also water. Thesporesgerminate into a tiny eco-friendly thread, which looks prefer a simple strand ofgreen algae. This similarity is one an ext clue that bryophytes aredescendedfrom environment-friendly algae. This early on threadlike stage is referred to as the protonema(= an initial thread, plural = protonemata, like stigma/stigmata). The newadultgametophytes flourish from a tiny bud that creates on the protonema.Eventuallythese gametophytes will flourish to develop gametes, and the totality cyclewillstart over again. Mosses can likewise reproduce asexually through fragmentationor by growing tiny vegetative buds dubbed gemma, which have the right to break offand flourish into a new plant .
While bryophytes in general are an ext interesting than important, inthe usual sense, a conspicuous exception are mosses that the genus Sphagnum.Sphagnummoss forms dense mats which come to be compressed into peat, which deserve to beusedas fuel, back it’s very smoky. Peat additionally contains other plants suchas reeds, that thrive amid the sphagnum. In dried form, peat moss isremarkablyabsorbent and, and has been offered for diapers, because that enriching bad gardensoils, and also as a field dressing for wounds. Whereas noodle absorbs 4-6timesits dried weight, dried sphagnum have the right to absorb 20 time its own weight influids!Peat bogs are an extremely important and also interesting ecosystems. Sphagnummosses greatly increase local acidity by publication H+ ions, and also the pHof peat bogs have the right to drop come 4 or lower, perhaps the many acidic naturalenvironment.Peat bogs cover about 1% that the Earth’s land surface, an area abouthalfthe size of the united States.
Division Hepaticophyta - (9,000 sp.), liverworts, Marchantia,Conocephalum, Porella
Liverworts have the easiest bodies of every the green plants. Thegametophyte,the dominant stage, looks choose a level scaly leaf, with influential lobes.It watch for all the world like a small flattened liver, thus thescientificname hepatico-phyta = liver plant. Throughout the center Ages, thissimilaritycaused physicians to prescribe liverwort for diseases of the liver.Accordingto the theory 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 organs of the body they weresupposedto heal! for this reason liver-wort, wyrt gift the Anglo-Saxon word for herb.Theshape the the liverwort to be the signature of the Creator in nature. Canyou guess what walnuts were supposed to cure ? (diseases of thebrain)
Liverworts re-superstructure the basic properties of bryophytes, however are notveryclosely related to mosses or hornworts. Numerous botanists think castle mayhaveevolved independently, from a different group of green algae. For onething,liverworts don’t save food together starch yet as oils. If you obtain theaquaticliverwort Porella in lab, take a sniff of the jar, yet not toodeep!It smells that rancid oils, oils the went a little funky when the plantwas gift shipped. Another characteristic distinct to liverworts is theirlack of stomata, i m sorry are uncovered in all other plants, including mossesand hornworts.
In many species of liverworts, such together Marchantia, the oneyouwill most most likely see in lab, the antheridia and archegonia are not ontopof the plant, but hanging under from the underside of odd littlestructuresthat look choose tiny umbrellas. (These umbrella-shaped frameworks arecalledthe antheridiophore and archegoniophore). The bi-flagellated spermswimsto the egg, and also fertilization takes ar to type a diploid (2N)zygote.The tiny diploid sporophytes, which remain attrached to the parentplant,have a very simple structure. Meiosis within the sporophyte produces anumber that haploid spores. These spores room surrounded through curious longandtwisted moist cells called elaters. Once the capsule dries and bursts,the elaters twist and also jerk roughly in a method that scatters the spores inall directions. Liverworts can likewise reproduce asexually by way ofspecialstructures called gemmae cups. These tiny cups deserve to be easilyseenon the surface ar of the plant. Every gemma cup has a number of tinyplantletscalled gemmae, and also a single drop the water will disperse them. Theselittlevegetative “clones” will certainly then thrive into a brand-new gametophyte.
Division Anthocerophyta - (100 sp.), hornworts, Anthoceros
The green gametophytes the the hornwort look really much favor aliverwort.But their little sporophytes more closely resemble those of mosses. Thesporophytes thrive out of the gametophyte, and also look favor a tiny uprighthorn. Choose mosses, hornworts have stomata, and so are probably morecloselyrelated come mosses and also other plants than to the liverworts castle matresemble.These plants room symbiotic v 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 View
Examine the living mosses top top display. Notification the small capsuleson peak of the tiny sporophytes. Mosses generally grow in one of twogrowthtypes: cushiony moss and also feathery moss.
Examine slides the the antheridia and also archegonia. The sausageshaped antheridia create sperm, and the flask shaped 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 resemblance is added evidence that greenalgaegave rise to all higher plants.
Examine the terrestrial liverworts Marchantia and also Conencephalum(oneor both should be ~ above display). Exactly how does their development habit different fromthat that the mosses? have the right to you see any type of gemmae cups top top the uppersurfaceof this plants?
Examine slides that the liverwort Marchantia.
Examine the aquatic liverworts like PorellaandRiccia(one or both have to be ~ above display). An alert how they different from themoreterrestrial creates of liverwort.
Look at the preserved liverworts, and also observe their distinctreproductive structures (they watch like little green umbrellas). Howdoestheir life cycle differ from mosses?
Examine slides that the hornwort Anthocerophyta.Things to Remember
Know the life cycle of the moss in detail, and be may be torecognizethe miscellaneous stages.
Hint: Be sure you understand the general life cycle ofplants,and deserve to tell which 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 every one of them are variations top top the samebasictheme.Ecological, Evolutionary, and Economic Importance
Mosses are essential in landscaping and gardening, specifically peatmoss(Sphagnum).
Peat moss (Sphagnum) has been supplied historically as dressingsfor wounds.
Peat moss have the right to be provided as fuel.
Mosses are the many primitive life land plants.
Hornworts save on computer symbiotic swarms of the cyanobacteria Nostoc.
shining society moss
Introduction to Tracheophytes - Ferns and also Fern Allies
Tracheophytes (vascular plants) completed the conquest of theearth’s surface started by the an ext primitive bryophytes. Just as theevolutionof spores to be the key to the intrusion of the land surface ar bybryophytes,the invention of facility vascular tissues let tracheophytes completetheconquest of dry land. There are about 250,000 varieties of vascularplants,grouped in ripe divisions. Tracheophytes all have a well developedroot-shootsystem, through highly specialized roots, stems, and leaves, andspecializedvasculartissue (xylem and phloem) that duty like miniature tubes toconductfood, water, and also nutrients throughout the plant. Due to the fact that ferns and fernallies posses true vascular tissues, they can grow to be much largerandthicker than the bryophytes.
The ferns and fern allies (non-seed tracheophytes) mark two majorevolutionarystrides. In these and also in all much more advanced plants, the leafy green diploidsporophyte currently becomes the dominant stage. The tiny gametophytemay be one of two people autotropophic (like the fern prothallus) orheterotrophic(like the gametophytes of some lycopsids), and is generally free livingand independent of the parental sporophyte. Unequal the vascularsporophytes,the gametophytes have actually no vascular tissue at all. These 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 are still restricted tomoisthabitats. Their flagellated sperm require a slim film that water to swimbetweenthe antheridium and the archegonium. And when the infant sporophyte growsup native 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 renders sense, due to the fact that it way onlyoneset the gametes needs to make the perilous journey outside of theorganism.
ground pine tree (Lycopodium) reflecting strobili
The ferns and fern allies germinate from spores. These plants aremostlyhomosporous- their spores room identical and you can"t differentiate which willgrow right into male or mrs plants. Lock are additionally monoecious -boththe archegonia and also antheridia (male and also female reproductive structures)are borne on the same plant. Comparison these primitive vascular plantswiththe an ext advanced seed plants, the gymnosperms and angiosperms, whichgerminatefrom seeds quite than native spores. Seed plants are all heterosporous.It is basic to differentiate the larger female megaspore fromthesmaller masculine microspore. The sperm of particle plants have actually noflagella.They lack antheridia, and also only a couple of still have actually an archegonia. Unlikethemore primitive ferns and also fern allies, seed plants are largely dioecious,having different male and also female plants.
In many of this primitive plants, specific leaves space specializedforreproduction. These modified leaves, or sporophylls, be affected by each other thesporangiaat their bases. These sporophylls typically branch the end from a shortenedstem,forming a society shaped structure dubbed a strobilus. The pineconeand the flower are intricate variations on this primitive strobili.
There room four departments of non-seed tracheophytes, vascular plantsthat reproduce by way of spores, the Psilophyta, Lycophyta,Sphenophyta,and Pterophyta. Before these non-seed tracheophytes evolved, thebryophyteswere the dominant type of plant life. The evolutionary edge of having actually amore reliable conducting system, and a well-developed root-shootsystemenabled them come outcompete bryophytes. If you’re lucky enough to seegroundpine or other club mosses growing in the shade of a huge pine tree,thinkfor a moment around how these tiny plants were when the masters of theplanet,forming huge forests through 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= 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 of alarge and widespread group of early on land plants. In addition to thelivingDivision Psilophyta, the psilopsids, there space two extinct departments ofprimeval vascular plants. The primitive whisk ferns resemble theseextinctpioneers in plenty of ways. They room the just living vascular tree thatlacka root-shoot system, a characteristic castle share v both extinctDivisionsof genealogical vascular plants. Some current molecular proof suggeststhatone, or also both, that the living genera the psilopsids may actually bemoreclosely related to ferns, prefer a fern that has reverted come moreprimitivetraits. If this is true, then Psilophyta will join the ranks of thenumerousextinct departments of plants.
Psilopsids are discovered in tropical and subtropical areas, and also occursthroughoutthe southern US. I once found one farming on my earlier porch under theleavesof a spider plant. Whisk ferns room a common weed in greenhouses alloverthe world. They are straightforward green upright stems, v dichotomousbranching.They have no leaves, and also no true roots. The external tissues of the stemdoall the photosynthesizing. A portion of the stem dubbed 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 at the same allude 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 mommy cell creates haploid spores by meiosis.Their gametophytes space tiny tiny thread-like underground plants thatlack chlorophyll, and live as heterotrophs in the soil, feather andactingmuch choose a small fungi. It actually has a symbiotic fungi, thesamemycorrhizae the live in the rhizomes of the adult sporophyte.
Division Lycophyta - (1,000 sp., fr. Gr. Lycos=wolf), clubmosses,quillworts, Lycopodium (podus=foot)
Their room only 5 living genera of lycopsids, but at one time fromthe far-off Devonian, about 400 mya, well right into the Carboniferous, theywere the dominant type of vegetation on the face of the Earth. Now theyare decreased to a shadow of their glorious past, inconspicuous littleplantsin the woodland understory. The tropical types are little epiphytes(plantsthat thrive on various other plants).
Their roots prosper from distinct underground stems called rhizomes, asdo many of these primitive tracheophytes. In some varieties thesporophyllsare combined in through the scale-like leaves. In many species, thesporophyllsare organized right into strobili, therefore the common name that “club moss”. Thesperm swim down the strobilus to the archegonia, and the zygote thatformsis maintained in the cone, i m sorry ripens and also falls come the ground. Thegametophytesare independent and free-living, They space curious creatures that lookandact nothing like their sporophyte parents. They deserve to be eitherheterotrophicor autotrophic, and usually have actually a symbiotic fungi associated withthem.Many of the lycopsids space 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 also railroad beds, andin weird corners of fields and also forests you might find another tiny plantquietly dreaming the its former splendor, the horsetail. Horsetailsappearedin the so late Devonian, and were amongst the dominant forest tree forhundredsof millions of years. Just one genus the Sphenophyta still exists, thegenusEquisetum,and it might be the oldest living genus of plants on earth. Horsetailstoweredamong the Carboniferous forests, getting to heights of 30-60 feet. Muchofthe coal deposits we make use of for fuel this day were created from horsetailsand other trees during the Carboniferous, toward the end of thePaleozoic.
Horsetails have actually true roots, stems, and also leaves, despite the leaves arelittle an ext than flattened stems. Their hollow, ribbed tribe arejointed,kind of favor a stalk that bamboo, and also a whorl of leaves arises at eachjoint.The plants are spread vegetatively through rhizomes. The stems feel veryrough,because the epidermal tissues are impregnated with tiny seed ofsilica(sand). This more than likely helps safeguard the plant against herbivores. Theserough stems do this plant appropriate for pioneer females to usage forscrubbingpots and also pans, thus its other common name, “scouring rush”.
The eco-friendly plant we check out is the diploid sporophyte generation. Thestalkscan be highly branched vegetative stalks, which in reality look likehorsetails, or straight unbranched reproductive stalks, which are tippedwitha big strobilus comprise the sporangia. The homosporous sporesdevelopinto a teeny-tiny eco-friendly gametophyte, simply 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 advanced from the psilopsids, sometime in theDevonian,relatively early in land tree evolution. Castle are really abundant anddiverse, ranging in dimension from a solitary centimeter to tree 24 meterstallwith 5 meter fronds. Ferns have been much better competitors through seedplantsthan various other seedless vascular plants, and also are a conspicuous part of thelandscape throughout the world, yet especially in the tropics, where75%of your 12,000 types occur.
Ferns are reasonably advanced plants, with true roots, trunk andleaves.The blade of the fern is referred to as a frond, and the tiny individualleafletsare referred to as pinnae. Ferns have true leaves, what botanists callmacrophylls.While the leaves of an ext primitive plants, which space calledmicrophylls,are simply extensions of the epidermis the the stem, the pipeline of fernsand greater plants were developed as a net of tissue extended betweensmallterminal branches. The pipeline of higher plants, and the modifiedleaves that comprise the pine tree cone and also the flower.
The life bicycle of the fern is usual of various other non-seed vascularplants.The leafy environment-friendly plant is the sporophyte. Productive fronds developsclustersof tiny sporangia on the underside that the frond. This clusters ofsporangiaare called sori (sing. Sorus). Sori space often safeguarded 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 evolved independently in numerous groupsofplants.
The haploid spores are formed by meiosis inside the sporangium. They ejected in a miniature explosion led to by the unequal drying ofthealternate thick and thin-walled cells the line the outer surface. Thetop traction slowly back until the reaches a an important point and also then snapsforward at an significant speed. At that size scale, the expulsion offernspores is one of the many explosive events in nature. The sporesgerminateinto small gametophytes. The tiny heart shaped gametophyte is referred to as aprothallus,literally “first-body” (pl prothalli). The prothallus has no vasculartissue.Its small size allows it rely totally on diffusion. Its tiny rhizoidsareassociated v mycorrhizal fungi. The tiny prothallus is green, andphotosynthetic, and bears one of two people antheridia and also archegonia, orsometimesboth together, top top its upper surface ar (lab slides have both top top sameprothallus).The archegonia are always found at the arch of the heart, and theantheridiaare tucked away amongst the small rhizoids at the other end. The spermswimsto the egg to fuse into a diploid zygote. The brand-new sporophyte growsdirectlyout that the peak of the gametophyte. Once it first begins come uncurl, thefrond looks like the scrolled neck that a violin or fiddle, and thisstageof advance is called a fiddlehead.
To Do and also View
Examine the life lycopsids ~ above display. Why space they calledclub mosses? an alert that quillworts and Selaginella space verydifferentin appearance native the society mosses.
Examine slides that Selaginella"s strobilus. Recognize megasporesand microspores.
Examine the living horsetails on display. Notice theprominentstrobiliofthe reproductive stalks, and also the bushy growth kind of the vegetativestalks(if available).
Examine the living whisk ferns ~ above display. Psilopsidshave a an easy dichotomous branching pattern. You may see small yellowsporangiaon the branches. Whisk ferns lack strobili. This primitive plants areclosely related to ferns.
Examine the life ferns top top display. Deserve to you see any kind of fiddleheads?Look for the rhizomes. Rhizomes are modified horizontal stemsbearingroots, that run along or simply underneath the ground, and also spread fernsandfern allies around.
Examine the living fern prothallus on display under adissectingmicroscope. Keep in mind its characteristic heart shape. Some prothalli mayhavea tiny new fern emerging from the notch of the "arch" heart, wherein thearchegoniaarelocated.
Examine slides that the prothallus: find the archegonia(can you watch an egg?).
Examine the fern leaflet on display under the dissectingmicroscope.Notice the influential indusia, and the small sporangiapeekingout from beneath. You"ll check out a couple of groups that sporangia that have losttheirindusium. If you"re lucky, together the heat of the microscopic lense dries out theleaflet, you can see the sporangia eject its spores. But don"tblink- it"s among the fastest and most explosive plot in nature. Use highpowerto watch the spores.
Examine slides that the sori and also indusia; use high powerto watch the spores.Things come Remember
Know the life cycle of the fern. Recognize specimens andslidesof the assorted stages.Economic, Ecological, and Evolutionary Importance
Ferns and fern allies are mostly responsible because that our moderndepositsof coal.
The fiddleheads of some types of ferns space edible.
See more: What Is An Unforced Error In Tennis, Unforced Errors In Tennis
Ferns are essential for the florist, gardening and landscapeindustries.Consider This
Why room all this plants minimal to wet habitats?
Which group of protists gave rise to these plants? (How perform we know?)
Why is the epidermis that the horsetail therefore rough? What does the needprotectionfrom?
All the the fern allies in this lab when towered 50-100 feet or more.What happened?
Links come Explore
Bryophyte taxonomy, images, and more at:
Get info about bryophytes from the Missouri botanical Garden at:
Lie down amongst the ferns at the American Fern Society, try theirlengthylist the links:
Basic information on ferns and fern allies, finish with images, courtesyof Texas A&M:
Look for ferns top top the "tree the life" at