-1-

Discipline: Botany Paper: Pteridophytes Lesson: Structure and Reproduction in Pteridophytes Lesson Developer: Dr.P.L.Uniyal Department/College: Department of Botany, University of Delhi Lesson Reviewer: Dr Satish Agarwal Department/College:Deshbandhu College Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL

Institute of Lifelong learning, University of Delhi

-2-

Table of Contents 

Introduction o Roots o Rhizomes/Stems o Leaves o Reproduction in Pteridophytes



Glossary



Exercises

Institute of Lifelong learning, University of Delhi

-3-

Introduction Pteridophytes have well defined root, stem and leaves in the sporophytic generation. All plant organs are covered by twice cuticle and xylem consist of lignified cells called tracheids. Cuticle and lignin are absent in bryophytes.

Roots 1. Pteridophytes develops primary roots directly from embryo which anchor the

soil and absorbs moisture and nutrient for uptake. (In fern – allies all species lack roots and rely entirely for water and nutrient uptake on a simple buried stem covered with rhizoids) (Fig.1). 2. Primary root does not grow very long and soon replaced by adventitious root. 3. Fern roots may have capacity of branching and each root can develop into a

long-lived system. 4. They lacks cambium therefore secondary growth does not occur. In trunk

forming ferns (eg., Cyathea, Dicksonia etc.) the roots grow downwards and adhere closely to the trunk until they reach the ground (Jones, 1987) (Fig.1,2,3).

Fig.1 Fern roots

Institute of Lifelong learning, University of Delhi

-4-

Fig.2 Fern roots

Fig.3 Parts of the fern plant

Institute of Lifelong learning, University of Delhi

-5-

Rhizome / Stems 1) Pteridophyte stem differs in shape, size and mode of growth. 2) It is usually called as rhizome. 3) Rhizome contains the growing point or meristem. 4) Rhizome may be of following types; I. II. III.

Creeping Erect Tufted (Caudex – small erect tufted rhizome) (Fig.4).

6. Rhizome may be Thin and wiry, Thick, Woody and Fleshy

Tufted or Erect Short – creeping

Medium – creeping

Long – creeping

Caudex

Fig.4 Types of Rhizomes

7. Vascular system of stem is called as stele. Stele consisted of xylem and phloem (Fig.5). Xylem comprises tracheids and phloem consists of sieve cells. Stele is of following types; i) Protostele – Central solid core of xylem surrounded by phloem (Fig.6) ii) Siphonostele – Parenchymatous pith is present in the centre which is surrounded by xylem and phloem (Fig.7)

Institute of Lifelong learning, University of Delhi

-6-

Fig 5. Main type of stele (diagrammatic)

Fig 6. Types of Protostele

Institute of Lifelong learning, University of Delhi

-7-

Fig 7. Types of siphonostele

Leaves 1.

Fern leaves are called as fronds.

2.

Young fern leaves are called as fiddlehead / crozier which is coiled just like the spring of a clock this type is known as circinate vernation (Fig.8).

CERCINATE VERNATION

Fig.8 CROZIER – YOUNG LEAF 3.

Fern – allies differs with ferns that they do not have distinctive fronds. Their leaves are small known as microphylls or linear as in Isoetes with a single vein and are arranged along simple or branched stem.

4.

Leaf has 3 parts; Stipe, Lamina and Rachis (Fig. 9,10,11).

Institute of Lifelong learning, University of Delhi

-85.

Stipe is the junction part of leaf which arises from rhizome and connect rest of leaf part.

6.

Lamina or main blade of leaf is the main green part of leaf which is photosynthetic

7.

Rachis is the middle stalk which is comparable to mid rib of the leaf.

8.

Fern fronds have simple and compound leaf.

Fig. 9 Parts of leaf

Fig.10 Parts of leaf

Institute of Lifelong learning, University of Delhi

-9-

Fig. 11 Parts of leaf

Fertile parts 1. Pteridophytes reproduced by spores,which are unicellular structure. 2. Spores are produced by meiotic division in specialized structure called sporangia. A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. 3. In majority of ferns sporangia are smaller, clustured and distinct groups called as sori. 4. Each sporangium is attached to the frond by a short stalk 5. Most Pteridophytes, are homosporous (only one kind of spore is produced). and some ferns are heterosporous (two kinds of spores are produced). 6. The fern – allies reproduced by the spores which are produced from sporangia. 7.

The sporangia, are borne in the axils or on the apices of specialized sporophylls not on the lower surface of leaves as in the ferns

8. However, in most heterosporous pteridophytes there are two kinds of sporangia, termed as microsporangia and megasporangia. (eg. Homosporous

Institute of Lifelong learning, University of Delhi

-10fern



allies

are

Psilotum,

Tmesipteris,

Lycopodium,

Equisetum

and

Phylloglossum and Heterosporous fern – allies are Selaginella and Isoetes ). 9. Microsporangia produce microspores and megasporangia produces megaspores, these give rise to two kinds of gametophytes that are functionally male or female, respectively. 10. In some cases, both kinds of spores are produced in the same sporangium, and may even develop together as part of a spore tetrad. 11. A

few

ferns

(Salviniaceae and Marsileaceae)

and

most

lycophytes

Selaginella and Isoetes and the extinct lepidodendrids are heterosporous with two kinds of sporangia, as are all the seed plants. 12. Sporangia can be terminal (on the tips) or lateral (placed along the side) of stems or associated with leaves. 13. In ferns, sporangia are typically found on the abaxial surface (underside) of the leaf and are densely aggregated into clusters called sori. 14. In some species, they are protected during development by a scale or film of tissue called the indusium, which forms an umbrella-like cover. 15. Sori

occur

on

the sporophyte generation,

the

sporangia

within

producing haploid meiospores. 16. Sori may be covered by a structure of extension of lamina cells called an indusium. Some ferns have their sporangia scattered along the margin of the leaf. 17. Lycophytes, in contrast, bear their sporangia on adaxial surface (the upper side) of leaves or laterally on stems. 18. Leaves that bear sporangia or sori are called sporophylls. 19. If the plant is heterosporous, the sporangia-bearing leaves are distinguished as either microsporophylls or megasporophylls.

Institute of Lifelong learning, University of Delhi

-11Eusporangia and leptosporangia 20. Categorized

on

the

basis

of

developmental

sequence, eusporangia

and

leptosporangia are differentiated in the vascular plants. 21. In a leptosporangium, found only in ferns, development involves a single initial cell that divide and develop the stalk, wall, and spores within the sporangium. There are around 64 spores in a leptosporangium (Fig.12). 22. In a eusporangium, characteristic of all other vascular plants and some primitive pteridophytes, the sporangial initials are present in a layer (i.e., more than one). A eusporangium is larger (hence contain more spores), and its wall is multi-layered. Although the wall may be stretched and damaged, resulting in only one cell-layer remaining (Fig.13).

Fig. 12 Leptosporangium development

Institute of Lifelong learning, University of Delhi

-12-

Fig. 13. Eusporangium development

Synangium 23. A cluster of sporangia that have become fused in development is called a synangium (Fig.14, 15). 24. Synangia

is

most

prominent

in

Psilotum

and

Marattiaceae such

as Christensenia, Danaea and Marattia. (http://en.wikipedia.org/wiki/Sporangium)

sporangium

Fig.14 Synangia

Fig. 15 Enlarge view of a Synangium

25. As the sporongia mature, the indusium shrivels so that spore release is unimpeded.

Institute of Lifelong learning, University of Delhi

-1326. The sporangia then burst by wall shrinking in dry period and release the spores (Fig 17). 27. Sori may be circular or linear. 28. They may be arranged in rows, either parallel or oblique to the costa, or randomly. 29. Their location may be marginal or set away from the margin on the frond lamina. 30. Spores are of two types (Fig.16); i)

Bilateral, Monolete having single laesura

ii)

Tetrahedral, Trilete having trilete mark of laesura

laesura

Tri-radiate mark

Monolete

Trilete

Fig. 16 Basic spore shapes

annulas

stalk

Fig.17 Release of spores from a sporangium

Institute of Lifelong learning, University of Delhi

-14Reproduction in Pteridophytes There are 3 types of reproduction in Pteridophytes; 1) Vegetative i) By division ii) By bulbils or plantlets iii) By stolons iv) By offsets v) By gemmae 2) Asexual and 3) Sexual

Most Ferns bear Sporangia on their lower surfaces. These are often grouped into areas which are called a Sorus. (http://www.biologie.unihamburg.de/bonline/library/webb/BOT311/FERNS/fern_reproductive_cycle.htm)

Meiosis occurs inside the Sporangium and produces Haploid Meiospores

Rhizoids

Spore Gametophyte Antheridia Fig.18 Spores, gametophyte and gametangia 1. Ferns are Homosporous & produce one type of Spore. 2. The Spores germinate and produce Photosynthetic

Archegonia

multicellular

thalloid

Gametophytes also known as prothallus (Fig. 18). The prothallus may be Tuburous, Filamentous, Cordate-thalloid, Strap like or Ribbon like. Among these Cordate-thalloid is most common form in homosporous ferns. 3. These produce Rhizoids which absorb Water and provide anchorage. 4. An Apical Cell develops and resides in the Apical Notch.

Institute of Lifelong learning, University of Delhi

-15-

Gametangia Antheridia are produced on the gametophyte first and are found near the initiation point of the Rhizoids on the gametophyte (Fig. 18,19, 20, 21).

Antheridia

Antheridia are globular in shape and occur on the ventral side of the gametophyte.

Antheridium

The Sperm / Antherozoids are unicellular, uninucleate and spirally coiled with two apical flagella but they have multiflagellate in the order Psilotales, Equisetales and Pteropsida

Institute of Lifelong learning, University of Delhi

-16Archegonia are produced after the maturation of antheridia and are found near the Apical Notch on ventral side of gametophyte.

Ar

Once Fertilization occurs the Embryo develops within the Archegonium in a Prone orientation.

Institute of Lifelong learning, University of Delhi

-17The Shoot Apical Meristem Produces Simple Leaves and a Root develops opposite the Shoot

The Sporophyte continues to grow while the Gametophyte dies.

Fig. 19 A descriptive life cycle of fern http://www.biologie.uni-hamburg.de/bonline/library/webb/BOT311/FERNS/fern_reproductive_cycle.htm

Institute of Lifelong learning, University of Delhi

-18-

Fig. 20 Developmental stages of Lygodium japonicum (Thunb.) Sw. a,b. Bilateral spores, c. Emerging protonema and rhizoids, d. two-diamensional stage, e. Spatulate gametophyte, f. Cordate gametophyte, g. Gametophyte showing antheridia An-> Single antheridium An->,h. Archegonia below apical notch showin Ar-> , i. Bisexual gametophyte showing antheridia and archegonia, j. Sporophyte in isolate culture, k,l. Sporophyte in composite culture Author’s Communication

Institute of Lifelong learning, University of Delhi

-19-

Fig. 21 Developmental stages of Lygodium flexuosum (L.) Sw. a,b. Bilateral spores, c. Emerging protonema and rhizoids, d. Filamentous stage, e. two-diamensional stage, f. Spatulate gametophyte, g. Cordate gametophyte, h. Gametophyte showing antheridia An-> i. Single antheridium An->, j. Archegonia below apical notch showin Ar-> , k. Single archegonium Ar->, l. Sporophyte in composite culture Author’s Personal Communication

Glossary (http://www.uwgb.edu/biodiversity/herbarium/pteridophytes/pteridophyte _glossary01.htm)

abaxial. Refers to the side of the frond that is away from the central axis of the stem. Many people intuitively call this the "underside" of the frond because as the fronds lean slightly outward they bend over to some degree, making the abaxial surface the

Institute of Lifelong learning, University of Delhi

-20lower or under surface. This is the surface on which the sori are produced. Contrast with "adaxial". adaxial. Refers to the surface of the frond that faces the axis of the stem or faces inward when the fronds are arranged in a roughly circular clump. Many people intuitively call this the upper or top surface of the frond because as the fronds lean slightly outward they bend over to some degree, making the adaxial surface the upper or top surface. auricle. An ear-like projection of a pinna or pinnule. bi-pinnate blade. A blade that is divided into pinnae and each pinnae is again fully divided into smaller segments (called pinnules). blade. The flat, green portion of a frond. Some fern books refer to the blade as the lamina (plural: laminae). costa. Plural: costae. The central axis or midrib of a pinna. fertile frond. A frond bearing sori. Contrast with a sterile frond which has no sori. frond. A leaf of a fern. The fern stems are often at or below the soil surface and are very inconspicuous, so the fronds are the portion of ferns that most people see. Fronds may be as small as one inch in length or as much as 3 feet or more and they may range from undivided to divided several times into very small segments. glands. Tiny structures found on the surface of some fern fronds. They often appear as very short hairs with an enlarged distal (free) end. Glands are very fragile and may be worn away on older fronds. Observation of glands often requires the use of a hand lens. hydathode. In some taxa, such as Dryopteris, the veins end in raised, broadened tips, without reaching the margin of the blade segments. These "hydathodes" are often whitish in color, and better observed on the adaxial (upper) surface of the frond. indusium. Plural: indusia. A covering over a sorus. Indusia are often thin and fragile and may be easily broken. The shape of indusia, how they attach to the frond, and their location on the frond are often important characters in keys to the ferns. pinna. Plural: pinnae. A segment of a blade produced by one level of division. If a blade is once pinnate, the segments formed are pinna. Each pinna can be further divided into segments called pinnules. pinnate. A term describing a common method of division of fern fronds, in which the blade is divided into segments arising from both sides of a central axis (rachis). Each segment of the blade could then be divided again in a pinnate fashion, making the blade bi-pinnate or twice pinnate. The process can be continued to further levels of division--see "bipinnate" and "tripinnate" for examples. pinnatifid. Similar to pinnate, except the blade is deeply divided but not deeply enough to produce separate segments, i.e. at least a narrow strip of green blade remains along the rachis (central leaf axis).

Institute of Lifelong learning, University of Delhi

-21pinnule. A segment of a blade produced by two levels of division. If a blade is once pinnate, the segments formed are pinna. Each pinna can be further divided into segments called pinnules. pubescent. A general word referring to any kind of hairiness of the plant parts. In some fern books the word "indument" is used to describe all hairs and scales collectively. rachis. The central axis of the frond; it might be called a mid-rib. scales. Small, flat, leafy structures sometimes attached to the rachis or stipe of a frond, or to the costae. They are generally brown or blackish rather than green. simple leaf. A leaf with an undivided blade. sorus. Plural: sori. A cluster of sporangia (the structures which produce spores). The shape of the sorus and its location on the frond are often important characters in identifying ferns. sporangium. Plural: sporangia. The roughly spherical structures which produce spores on the surface of fern fronds. When the sporangia are mature they open to release the spores. Usually several to many sporangia are attached near one another in conspicuous clusters. These clusters of sporangia are known as sori. sterile frond. A sterile frond is a frond that bears no sporangia, and therefore has no sori. In some species the sterile fronds are the same shape ans size as the fertile fronds. In other species sterile and fertile fronds may differ in size and or shape. stipe. A continuation of the rachis below the base of the blade. It is in effect the petiole of the leaf (frond). tri-pinnate. A blade that is divided into three levels of segments. The blade is divided into segments called pinnae, each of the pinnae is again divided into segments, and those segments are again divided. ultimate segment. The smallest level of segments into which a blade is divided. If a blade is once pinnate, the pinnae would be the ultimate segments. If the blade was twice pinnate into pinnae and pinules, then the pinnules would be the ultimate segments, etc.

Institute of Lifelong learning, University of Delhi

-22-

Exercises 1. Draw a labeled diagram of a fern sporophyte 2. Define types of stele 3. Write a short note on the following (i) Fern and fern-allies (ii) Eusporangiate and Leptosporangiate (iii) Spores of pteridophytes (iv) Reproduction in pteridophytes

Objective Question Question Number

True / False

1. The main plant body of pteridophyte is gametophytic.

True or False

2. Fern roots may have capacity of branching and each root can

True or False

develop into a long-lived system. 3. Stem of pteridophytes lack cambium, therefore secondary growth does not occur. 4. Stem is usually called as Rhizome

True or False

5. Fern leaves are called as fronds

True or False

6. In ferns, sporangia are typically found on the adaxial surface (upperside) of the leaf 7. Sori may be covered by a structure of extension of lamina cells called an indusium 8. Gametangia are the male and female sex organs on prothallus

True or False

9. Rhizoids absorbs Water and provide anchorage.

True or False

10. Flagella are found in sperms

True or False

True or False

True or False True or False

Multiple Choice Questions 1. A single initial cell that divide and develop the stalk, wall, and spores within the sporangium is called as ; a) Leptosporangiate type development b) Eusporangiate type development c) Synangium 2. More than one cell divide and develop the stalk, wall, and spores within the sporangium is called as ; a) Leptosporangiate type development b) Eusporangiate type development c) Synangium 3. Synangia is most prominent in;

Institute of Lifelong learning, University of Delhi

-23a) b) c) d)

Psilotum Pteris Adiantum Lycopodium

4. The prothallus may be of ; a) Tuburous, b) Filamentous, c) Cordate-thalloid, d) Strap like e) Ribbon like f) All of the above 5. Antheridia develops ; a) Below the apical notch on the dorsal surface b) Below the apical notch on the ventral surface c) In between rhizoids on the ventral surface d) In between rhizoids on the dorsal surface 6. Archegoina develops ; a) Below the apical notch on the dorsal surface b) Below the apical notch on the ventral surface c) In between rhizoids on the ventral surface d) In between rhizoids on the dorsal surface 7. Antherozoid and egg fuse to form ; a) Zygote b) Gamete c) Embryo d) Sporophyte Fill in the Blanks 1. Spores of ferns are of …………types. They are ……….. and … ……… 2. Photosynthetic multicellular thalloid Gametophytes also known as ……………. 3. Gametangia are……. ….and ………. 4. Sperms have ………. flagella 5. A cluster of sporangia that have become fused in development is called a ……….. Match the Following 1. 2. 3. 4. 5. 6. 7. 8.

Rhizoids Rhizome Fronds Antheridia Archegonia gametophyte Unicellular and spirally coiled 2 flagellated structure Crozier / fiddlehead

a) b) c) d) e) f) g) h)

Institute of Lifelong learning, University of Delhi

Prothallus Male sex organs Young coiled leaf Sperm Stem Leaf Female sex organs Root

-24ANSWERS Answer : True/False 1.

The plant body of pteridophyte is gametophyte.

False

2.

Fern roots may have capacity of branching and each root can develop

True

into a long-lived system. 3.

They lacks cambium therefore secondary growth does not occur.

True

4.

Stem is usually called as Rhizome

True

5.

Fern leaves are called as fronds

True

6.

sporangia are smaller, clustured and distinct groups called as sori

True

7.

In ferns, sporangia are typically found on the adaxial surface (upperside) of the leaf Sori may be covered by a structure of extension of lamina cells called an indusium Gametangia are the male and female sex organs on prothallus

False

8. 9.

True True

10. Rhizoids absorbs Water and provide anchorage.

True

11. Flagella are found in sperms

True

Answers : MCQs 1. 2. 3. 4. 5. 6. 7. Fill in the blanks: Answers 1. 2. 3. 4. 5.

a b a f c b a

two, bilateral,Tetrahedral prothallus Antheridia,Archegonia two synangium

Match the following : Answers 1. Rhizoids h) Root 2. Rhizome e) Stem 3. Fronds f) Leaf 4. Antheridia b) Male sex organs 5. Archegonia g) Female sex organs 6. Cordate gametophyte a) Prothallus 7. Unicellular and spirally coiled 2 flagellated structure d) Sperm 8. Crozier / fiddlehead c) Young coiled leaf

Institute of Lifelong learning, University of Delhi

-25-

Institute of Lifelong learning, University of Delhi

Structure and Reproduction in Pteridophytes.pdf

Pteridophytes have well defined root, stem and leaves in the sporophytic generation. All plant organs are covered by twice cuticle and xylem consist of lignified ...

2MB Sizes 26 Downloads 65 Views

Recommend Documents

Morphology, Anatomy and Reproduction of Sphagnum.pdf ...
There was a problem loading this page. Morphology, Anatomy and Reproduction of Sphagnum.pdf. Morphology, Anatomy and Reproduction of Sphagnum.pdf.

Morphology, Anatomy and Reproduction of Marchantia.pdf ...
Morphology, Anatomy and Reproduction of Marchantia.pdf. Morphology, Anatomy and Reproduction of Marchantia.pdf. Open. Extract. Open with. Sign In.

Morphology, Anatomy and Reproduction of Psilotum and Selaginella.pdf
Page 3 of 38. Morphology, Anatomy and Reproduction of Psilotum and Selaginella.pdf. Morphology, Anatomy and Reproduction of Psilotum and Selaginella.pdf.

[PDF] Download Ebook Genetics of Reproduction in ...
Page 1 .... MLA APA Chicago Harvard Artisteer web design generator for Joomla templates Wordpress themes Drupal themes Blogger templates and DNN skins.

pdf-1172\family-secrets-risking-reproduction-in-central-mozambique ...
Try one of the apps below to open or edit this item. pdf-1172\family-secrets-risking-reproduction-in-central-mozambique-by-rachel-r-chapman.pdf.

[Ebooks] Download Reproduction in Education, Society ...
Reproduction in Education, Society and Culture, 2nd Edition (Theory, Culture Society) .... of Geometric Analysis 1 ebook Science Technology book download free.

[J502.Ebook] Free PDF Color And Its Reproduction ...
Jul 30, 2004 - Nonetheless, some people will certainly seek for the very best vendor ... Scientist and Professor at the California Polytechnic State University.

Reproduction, Body Size, and Diet of Polychrus ...
9Sam Noble Oklahoma Museum of Natural History, 2401 Chautauqua, Norman, Oklahoma 73072 USA. 10Department of Biology, Brigham Young ... reveals the influence of phylogenetic history (Ballinger, 1983;. Dunham and Miles, 1985). ...... PIANKA, E. R., AND

Morphology Anatomy and Reproduction of Anthoceros .pdf ...
Genus: Anthoceros. Page 3 of 42. Morphology Anatomy and Reproduction of Anthoceros .pdf. Morphology Anatomy and Reproduction of Anthoceros .pdf. Open.