PLANTAE

Laboratory Report 3 : Bryophytes and Ferns

Introduction

Bryophyte is a traditional name used to refer to all embryophytes (land plants) that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin they are not considered to be true vascular tissue. !urrently bryophytes are thought not to be a natural or  monophyletic group; however the name is convenient and remains in use as a collective term for  mosses mosses hornwor hornworts ts and liver liverwor worts. ts. Bryophy Bryophytes tes produc producee enclose enclosed d reprod reproducti uctive ve struct structures ures (gametangia and sporangia) but they produce neither flowers nor seeds reproducing via spores. " broad consensus among systematists has recently emerged that bryophytes as a who le are not a natural group (paraphyletic) although each of the three e#tant (living) groups is monophyletic. $he three lineages are %archantiophyta (liverworts) Bryophyta (mosses) and "nthocerotophyta (hornworts). &ie all land plants (embryophytes) bryophytes show 'alternation of generations'. " haploid gametophyte each of whose cells contains a fi#ed number of unpaired chromosomes gives rise to a diploid sporophyte each of whose cells contains twice the number of paired chromosomes. ametophytes produce sperm and eggs which fuse and grow into sporophytes. Sporophytes produce spores which grow into gametophytes. n the other hand a fern is any one of a group of about *+,,, species of plants belonging to the  botanical group nown as teridophyta. nlie mosses they have hav e #ylem # ylem and phloem that mae them vascular plants). $hey have stems leaves and roots lie other vascular plants. /erns reproduce via spores and have neither seeds nor flowers. &ie all other vascular plants they have a life life cycle cycle referr referred ed to as altern alternati ation on of generat generation ions s charact characteri erized zed by altern alternati ating ng diploi diploid d spor sporoph ophyt ytic ic and hapl haploi oid d gamet gametoph ophyt ytic ic phase phases. s. $he $he dipl diploi oid d spor sporoph ophyt ytee has has +n paire paired d chromosomes where n varies from species to species. $he haploid gametophyte has n unpaired chromosomes which is half the number of the sporophyte. $he gametophyte of ferns is a freeliving organism whereas the gametophyte of the gymnosperms and angiosperms is dependent on the sporophyte. Procedure

*. $he live specimens were observed using dissecting microscope. +. $he prepared slides were observed using light microscope under the suitable magnification.

Discussion

0uring this lab activity two groups of plants have been e#amined which are bryophytes and ferns. /or bryophyte we have e#amined mosses liverworts and hornworts. /irstly 1 have e#amined the live specimen of liverworts which is  Marchantia .  Marchantia  belongs to the class 2epaticae. 1t grows well in shaded and moist areas such as greenhouses the  bans of streams. 1t rapidly colonizes burnt ground after fires. /rom my observation 1 found that %archantia do not have true leaves lie most organisms we consider plants but it have green leaf-lie structure called thallus. 1n addition %archantia do not have roots they have rhizoids which are root-lie structures that lac #ylem and phloem. "bsorption of water and nutrient from the soil is carried out by these unicellular rhizoids which are also used for attachment of the thallus to the surface of the soil. Besides that %archantia do not have flowers instead they have archegoniophores and antheridiophores (female and male se# organs). $hey are unise#ual or also called as dioicious since the male and female se# organs forming on different plants. $he male and female plants can be easily identified by their gametangia which are very distinct structurally. "ntheridiophores loo lie an umbrella while the female achegoniophores have finger-lie pro3ections.  4e#t 1 have observed the live specimen of hornworts which is Anthoceros.  Anthoceros is a genus of hornworts in the class "nthocerotea. "ll the species of "nthoceros grow on moist clayey soil and on wet rocs in very moist shady places usually in dense patches. " few species of "nthoceros occur on decaying wood. 2ornworts are similar to the thallose form of liverwort  but instead of the normal liverwort type of sporophyte they have a hornlie structure. $he thallus structure of hornworts is simple much simpler than %archantia. $he sporophyte of "nthoceros includes the capsule and seta while the gametophyte is the leafy plant. "nthoceros reproduces  both by se#ual and ase#ual means. "se#ual reproduction usually taes place by tubers which are able to withstand unfavourable conditions. ther means of ase#ual reproduction include fragmentation gemmae formation persistent growing apices and apospory. Se#ual reproduction occurs through development of embedded antheridia and archegonia. $he thallus of anthoceros can be monoecious or dioecious. $he most familiar Bryophytes are mosses. $rue mosses are usually divided into two large groupings that are "crocarps and leurocarps. 0uring the lab 1 have observed the live specimen of olytricum sp. olytrichum is an acrocarpous moss and "crocarps have capsules at the tips of  their branches. 1n moss the dominant generation is the leafy haploid (n) form called the gametophyte. $he gametophytes are either male or female. $he male gametophyte produces sperm from structures called the antheridia. $his male gametophyte is haploid (n) and is  produced by mitosis. $he female gametophyte produces an egg from structures called the archegonia. $his female gametophyte is also haploid (n) and produced by mitosis. Both the male antheridia and the female archegonia are located on short stems. $he se# organs located at the apical end of stem or branches and are protected by a leafy structure called paraphyses. $he

gametophyte of mosses develops in two stages. $he first stage is the development of protonema from spore. rotonema is a green 5algal-lie6 and appears as branching filaments of cell. rotonema produces bud and will develop into young mosses plants (leaflie). 7hen observing under the microscope protonema appears as an elongate thread-lie structure. $he structure also has perpendicular crosswalls short cells and irregular branching. $he moss protonema that 1 have observed was 3ust developing into chloronema because the cell is still short and the crosswall is perpendicular. 1n addition mosses can also reproduce ase#ually by fragmentation or   by growing little vegetative buds called gemma which can brea off and grow into a new plant. &astly 1 have observed another group of plant different from bryophyte that is fern. /rom my observation the structure of fern consists of rhizome the part of a fern from which the fronds (leaves) and roots grow. /ronds are the leaves of a fern consisting out of + parts8 the stipe and the lamina. $he part between the rhizome and the first leaflet is called stipe it is analogous to the  petiole of a leaf. $he lamina is the blade of the fern it is usually green and responsible for the  photosynthesis. $he lamina consists of a midrib (rachis) and of pinnae. " pinnae is the first division of the front this can be further divided into pinnules. "n easy way to recognize a fern is the rolled up state of the young leaves (fiddleheads or croziers) a condition better nown as circinate vernation. /erns do not have flowers. $hey reproduce through spores which are  produced in sporangia. 1n true ferns these are situated in groups called sori. $hese are usually located on the underside of the fronds. Sometimes the sori are protected by flaps or dis  structures called indusia or covered by the rolled over edge of the pinnae. nlie the other vascular plants the flowering plants and conifers where the adult plant grows immediately from the seed ferns reproduce from spores and an intermediate plant stage called a gametophyte. 1f the spore finds suitable conditions it will grow into a tiny heart-shaped  plantlet called a prothallus or gametophyte. $he prothallus is the fern gametophyte. 1t is a green  photosynthetic structure that is one cell thic usually heart or idney shaped. 1t is very difficult to find in the bush as it is so tiny. 1t doesn6t have roots stems or leaves but it does have rhizoids that anchor it to the soil and help with absorption. $he underside of the prothallus is where the gametes are produced from the male and female se# organs. $he prothallus has both male and female se# organs.  1n this regard the spore behaves 9uite lie the seed of a higher plant e#cept that what grows from the seed is the full adult plant but what grows from the spore is the gametophyte. $he gametophyte is not the full fern but a plant with only half the genetic material of the adult fern rather lie a sperm cell or an egg cell. $he gametophyte is the intermediate stage from spore to adult fern. 1f the gametophyte finds itself in a suitably moist place fertilisation taes place and it is transformed into a complete adult plant. 1t becomes what6s called a sporophyte. iven the right conditions this tiny sporophyte will continue to grow into a full adult fern where it can  produce spores of its own to repeat the life cycle. 1n some ferns the rachis produces a vegetative  bud or gemmae these ferns are called proliferous. 7hen this bud falls on the ground a new plant develops. Sometimes however the new plant will already start to grow while still being attached

to the rachis. $hrough the weight of this small plant the frond will bend towards the ground. 7hen it maes contact with the soil the small new fern can start to root. Conclusion

"s conclusion 1 can say that in Bryophyte the main plant body is a gametophyte and haploid. $he true roots leaves and vascular tissue are absent. Sporophyte is capsular and totally dependant on gametophyte. 7hile in fern the main plant body is a sporophyte and diploid. $he true roots leaves and vascular tissue are present. Sporophyte is differentiated to root stem and leaves and is initially dependent on gametophyte.