EXPERIMENT 2: Seedless Vascular Plants (Fern Allies and Ferns) OBJECTIVE • •
To identify the characteristics of fern. To study the structure and reproduction of seedless vascular plants.
MATERIALS •
Prepared slide of living or preserved -spike osses (Selaginella (Selaginella sp.) sp.) -ferns ( Dryopetris Dryopetris sp.) sp.)
•
!opound icroscope
PROCEDURE
". !opou !opound nd icro icroscop scopee is set up up on the the ta#le ta#le.. $. Prep Prepar ared ed slid slidee of of Sellaginella sp. is sp. is e%ained and recorded. &. This This procedu procedure re is repeate repeated d for anoth another er slide slide of Dryopteris of Dryopteris sp. and Fern Antheridia and Archegonia
POST-LAB QUESTIONS
". 'hat function function do you you think the the root-like root-like rhioids rhioids at at the #ase of of the plant plant perfor perfor The function of rhioids is to help organiss a#sor# nutrients* inerals and +ater. $. ,%plain ,%plain +hy +ater +ater ust ust #e present present for the the #ryophytes #ryophytes to coplete coplete the se%ual se%ual portion portion of their life cycle. The ale se% cell (sper)* antherooids of #ryophytes are otile and reuire a ediu to s+i in to reach the feale se% organ (egg)* archegonia for fertilisation. t is #ecause sper have flagella* +hich are +hip-like tails that allo+ the to s+i. n order to s+i* they need +ater. /ence +ater is essential as it #ecoes the ediu for the antherooids to s+i.
Sporophyte t is an independent plant +ith diploid chroosoe nu#er. n algae* the sporophyte is confined to ygote. n #ryophytes* the sporophyte is a cople% structure #ut is dependent on gaetophyte. n pteridophytes* gynospers and angiospers the sporophyte is doinant.
0aetophyte t is an independent plant +ith haploid chroosoe nu#er. n algae those and #ryophytes the gaetophyte is doinant.
n pteridophytes* gynospers and angiospers* the gaetophytes are very uch reduced. n lo+er groups of plants* sporophyte n lo+er group of plants* gaetophyte reproduces #y spores spores that give rise to reproduces vegetatively* ase%ually and gaetophyte. se%ually. Vegetative and ase%ual reproduction produces gaetophytes +hereas se%ual reproduction produces ygote* +hich represents the sporophyte. n higher plants sporophyte perfors n higher plants* the gaetophyte represents vegetative and se%ual reproduction. the gaetes only +hich fuse to for sporophyte. &. 1escri#e the difference #et+een a sporophyte and gaetophyte.
2. 3oung fern sporophyte (attached to the gaetophyte) +ill gro+ up to ature sporophyte. 'hat +ill happen to the gaetophyte 'hen the young sporophyte attached to the gaetophyte parent and receives nourishent fro it and #ecoe a ature sporophyte it +ill #ecoe independent plant* +hile the gaetophyte dies.
4. 'here is the location of antheridiu on fern gaetophyte /o+ does the sper fro the antheridiu fuses +ith the egg at archaegoniu The gaetophyte is the generation that gro+s fro a fern spore.
DISCUSSIONS
The genus Selaginella is classified as seedless vascular plants in the division 5ycophyta* +hich includes the nuerous plants coonly kno+n as clu# osses and spike osses. Siilar to their close relatives* Selaginella plants develop stro#ili* spike-like reproductive organs that for on fertile #ranches. At the tips of the #ranches are found stro#ili. The icrophylls in the stro#ilus are called sporophylls. ,ach sporophyll has a sporangiu in its a%il. The sporangiu consists of a stalk and a sterile 6acket of cells. nside the sterile 6acket are one or ore sporocytes +hich ultiately divide #y eiosis to produce spores. The spores are called egaspores #ecause of their large sie. This akes the sporangiu a egasporangiu and the sporophyll a egasporophyll. These nearly-icroscopic spores are called icrospores. This akes their sporangiu a icrosporangiu and the sporophyll a icrosporophyll. Since* Selaginella has #oth icrospores and egaspores* the plant is called heterosporous. 'hen the sporangia of a Selaginella stro#ilus reach aturity* they split open and release the spores they contain into the air. The egaspores give rise to feale gaetophytes kno+n as egagaetophytes and the icrospores develop into ale icrogaetophytes. The icrogaetophytes produce sper euipped +ith flagella that ena#le the to s+i to the eggs generated #y a egagaetophyte through +ater* either in the for of de+ or rain* in order to achieve fertiliation. The Selaginella sper ust s+i through the +ater-fil up the rhioids and into the cracked egaspore +all to reach the egagaetophyte inside. The syngay of egg and sper results in a ygote. This +ill develops into an e#ryo and ultiately an adult sporophyte.
1ryopteris coonly called +ood fern or ale fern that #elongs to phylu Pterophyta. The life cycle of ferns sho+ alternation of generations +here it involves alternation #et+een haploid gaetophyte and diploid sporophyte phases. n its sporophyte stage a typical fern has an underground ste kno+n as rhioes* true roots and true leaves kno+n as fronds. The rhioe or ste* roots and leaves are considered true #ecause they have special +ater-carrying tissues. As each young frond first coes out fro the ground* it is tightly coiled and kno+n as fiddlehead. As fiddleheads gro+* open out to for fronds. The frond is in copound for and is divided into saller leaflets and consists of t+o parts* a #lade and petiole.
The #lade is the #road* flat* photosynthetic surface of the frond and
contains the chloroplast. t also contains vascular tissue that #rings +ater and inerals fro
roots. 7n ost ferns* a #lade does not attach directly to a ste. nstead* a stalk or petiole attaches the #lade to the ste. The picture sho+ the spore production of ferns norally occurs on the underside of the leaves. Sporangia located in the underside of leaves occur in clusters kno+n as sori (singular8sorus). A sorus is group of spore-containing structures clustered on the underside of fern leaf. The sporogenous cells or spore other cells in the sporangia undergo eiosis to for haploid spores. Then the sporangia #reak open* it +ill release the spores. The spores then gerinate and undergo itosis to develop into ature gaetophyte.
The gaetophyte generation #egins +ith spores that have a tiny* green* norally heart-shaped structure. The fern gaetophyte is called prothallus. t does not have vascular tissue and has tiny* hair-like a#sorptive rhioids to attach it to the ground. These gaetophytes have #oth se%es present* +hich are antheridia and archegonia. Antheridiu is the ale part of seedless plants* like algae and fungi* and the archegoniu is the feale part. An archegoniu is a ulticellular structure or organ of the gaetophyte phase of certain plants producing and containing the ovu or feale gaete. The archegoniu has a long neck and a s+ollen #ase. Archegonia are typically located on the surface of the plant thallus* although in the horn+orts they are e#edded. The function of surrounding the gaete is assued in large part #y diploid cells of the egasporangiu inside the ovule. An antheridiu is a haploid structure or organ producing and containing ale gaetes called antherooids or sper. An antheridiu typically consists of sterile cells and speratogenous tissue. The sterile cells ay for a central support structure or surround the speratogenous tissue as a protective 6acket. The fertiliation occurs +hen the flagelatted sper cells s+i to the neck of an archegoniu through a thin fil of +ater on the ground under the prothallus. 7nce it is occurs* a diploid ygote undergo itosis to for ulticellular e#ryo. The e#ryo gro+s out fro the archegoniu of the gaetophyte. The sporophyte e#ryo attached and depends on the gaetophyte until it atures. As the e#ryo atures* the prothallus dry up and dies* and the sporophyte #ecoe free-living.
CONCLUSION
Seedless vascular plants consist of fern that divides into a fe+ phyla includes the Selaginella sp. and Dryopteris sp. This species have their o+n characteristics that help in their life cycle. 9oreover* it has gaetophyte and sporophyte generation in the ir reproduction cycle.
REFERENCES
!la%ton* . S.* eaves* S./.* and 1avidson 9.'.. (n.d). Selaginella Stro#ilus. ;etrieved fro http:<<+++.olypusconfocal.co
>2. Selaginella. Plant Physiology Information Website. ;etrieved fro http:<
RESULTS
Kingdom: Plantae Division: Lycopodiophyta Class: Isoetopsida Order: Selaginellales Family: Selaginellaceae Genus: Selaginella Magnication:
Selaginella stro#ilus
Kingdom: Plantae Division: Pteridophyta Class: Polypodiopsida Order: Dryopteridales Family: Dryopteridaceae Genus: Dryopteris sp! Magnication:
Dryopteris sp.
Kingdom: Plantae Division: Pteridophyta Class: Polypodiopsida Order: Dryopteridales Family: Dryopteridaceae Genus: Dryopteris sp! Magnication:
Fern Antheridia and Archegonia