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BIO102: Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

DIVERSITY OF

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www.bupoyesiku.net ~ 1 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Contents Topic: Diversity of Pteridophytes ...... 3 Objectives ...... 3 Reading Assignment ...... 3 Lecture ...... 3 Introduction ...... 4 Main Content ...... 4 Background of Pteridophytes ...... 4 Reproduction in Pteridophytes ...... 4 Vegetative reproduction ...... 4 Asexual reproduction ...... 5 Sexual reproduction ...... 5 Classification of Pteridophytes ...... 6 Characteristics of Pteridophytes ...... 7 Diversity of Forms in Pteridophytes ...... 7 Habitats of Pteridophytes ...... 9 Ecology of Pteridophytes ...... 9 Economic uses of Pteridophytes ...... 9 Conclusion ...... 10 Summary ...... 10 References/Further readings/Links ...... 10 Test Yourself Questions (TYQ)...... 11

www.bupoyesiku.net ~ 2 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Topic: Diversity of Pteridophytes

Objectives

In this lecture we will learn the followings:  Clear idea of the features that separate Pteridophytes from other  Skills in identifying them in our environment  Importance of the Pteridophytes  Contributions to our

Reading Assignment In addition to the discussion in this lecture you should read current textbooks in the library and visit: ilearn.bupoyesiku.net for the online lecture.

Lecture In previous lecture we discussed about non-vascular green plant . In our earlier lectures, you have learnt about the characteristics of the members of , lichen, fungi and monera. In our today’s lecture, we are going to be discussing the most advanced member of the plants, the Pteridophytes. You will be taken to the next level of understanding biodiversity with particular reference to vascular spore plants. is the first land vascular photosynthetic plants. They differ from angiosperm because their have apical that continues to grow in length for some time. And from other spore producing plant by bearing on the lower surface. They are important not only for academic teaching, but also for their unique and allies for aesthetic beautification of our environment. Furthermore, your knowledge of the field (Pteridology) will makes you more conscious of their abundance and important roles to humans. Especially for those of you that are going to become famous Pteridologists, as well as those that require the knowledge in their field of study.

www.bupoyesiku.net ~ 3 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Introduction Pteridology is the study of Pteridophytes. Like bryophytes and other non-vascular plants they primarily trap solar energy directly from the atmosphere and convert it to food. They form an advance producer in terrestrial food web of a typical ecosystem.

Main Content

Background of Pteridophytes Pteridophytes are the first with and . They reproduce by spores. Thus they are called vascular . It is important to know that the plants are probably descendants of certain extinct members of pteridophytes, . It is therefore obvious that some members are polyphyletic, from more than one ancestor. In addition, pteridophytes, probably evolved from the advanced green algae at about the same time as the first vascular seed plants because they both share multicellular sex organs, but the green algae lack vascular .

Reproduction in Pteridophytes Vegetative reproduction There are two describable types of vegetative reproduction in pteridophytes. Death of older portion of with separation of growing apices. Formation of on leaves, although very rare.

www.bupoyesiku.net ~ 4 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Asexual reproduction

Figure1.1 Fertile frond. Rachis (A), Pinnule (B), Sporangia (C)

Asexual reproduction occurs in the sporangia of the . Spores are gathered together into a group called sori, borne under the leaves surface. The form spore mother cells that meiotically form spores. When mature spores are dispersed and germinate under favorable conditions they produce a fertile and sterile fronds.

Sexual reproduction The undersurface of the green heart-shaped bears the , antheridia and archegonia (Fig 1.2). Fertilization depends upon a water film. The resulting sporophytes compose of rhizines (), fronds (leaves).

www.bupoyesiku.net ~ 5 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

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Figure 1.2 Simplified sexual cycle in Pteridophyte. Heart-shaped gametophyte (A), Female gametangium (B), Male gametangium (C), (D), Young (E), Rhizine (F), Spores (G).

Classification of Pteridophytes Under the current trend in classification, living members of pteridophytes consist of four major divisions,

 Psilotophyta (whisk ferns)  Lycopodiophyta  Sphenophyta and  Pterophyta.

It will interest you to know that Lycopodium spp. (Club ) share resemblance with and was in the past mistakenly classified under the Bryophyta.

www.bupoyesiku.net ~ 6 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Characteristics of Pteridophytes  Most fronds (leaves) are compound, although some are simple  Fertile leaves with spore on the undersurface and sterile leaves  Sporophyte is the dominant plant (independent of gametophyte)  Gametophyte () is free living small green heart-shaped plant  Leaves, large and pinnate (fronds)  Circinate vernation or fiddlehead (coiling leaves of young fern)  Stem or rhizome in horizontal underground near soil surface  Spores are house in sacs called sporangium under the leaves  Spore germinate to give filamentous and later green heart-shaped prothallus  Two types of spores ( and )

Diversity of Forms in Pteridophytes Pteridophytes have two alternating plant bodies the gametophyte and sporophyte.

Gametophyte for the first time in spore producing plants is dependent on the sporophytes for nutrient supply. The form of the gametophyte is heart-shaped and that of sporophyte is pinnate compound leaves (fronds). At this point it is important you to acquire the necessary skill to distinguish between the gametophyte of a thallus liverwort and that of a pteridophyte.

Club mosses (Lycopodium cernuum): Go online to view the images of club mosses

Spike mosses ( serpens): Go online to view the images of spike mosses

www.bupoyesiku.net ~ 7 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

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Figure 1.3 Portion of the of Selaginella serpens collected from the OOU BIOME, Ago-Iwoye, Nigeria. Lower large (A), Upper small leaf (B), Rhizine (C)

Quillwort (marsh plant with of tubular leaves, spores at the base): Go online to view the images of Quillwort

Marattioid fern: Go online to view the images of Marattioid fern

Horsetails ( spp.): Go online to view the images of horsetail.

Whisk ferns (Psilotophyta): Go online to view the images of Whisk ferns.

Adder’s tongue and Grape ferns (Ophioglossophyta): Go online to view the images of adder’s tongue and grape ferns.

Leptosporangiate fern (the largest member of ferns): Go online to view the images of ferns

www.bupoyesiku.net ~ 8 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Habitats of Pteridophytes As you have learnt in previous lectures, Pteridophytes are also native citizen of the entire world. They grow in great diverse habitats except in the marine Ocean. They are found in water as well as on land in marshy ground in shady situation. Major groups of substrate on which Pteridophytes grow are as outline here.

(branch, neck and trunk)  Rock (cracks and crevices)  Decaying and plant debris on forest floor  Bare ground  Artificial structures (culvert and old fences)

Ecology of Pteridophytes Pteridophytes are also important plants in the ecosystem. Pteridophyte members have functional stomata on the sporophytes. There has never been a record of pteridophyte fixing nitrogen gas into nitrate for other plant use. Other ecological importance of Pteridophytes is enumerated here.  Capture and recycling of nutrients wash with rainwater from the atmosphere.  Binding soil surface to prevent erosion  Providing seed beds for higher plants  Highly sensitive to habitat disturbances  Poor indicators of atmospheric pollution

Economic uses of Pteridophytes Besides the ecological role, pteridophytes have great economic and aesthetic values. Current trend in the use of ferns have stimulated interests in the field of pteridophytes. Leaves of ferns are traditionally used in floral arrangements. Some of the economic values are stated here.

 Leaf buds (fiddle heads) of some ferns are commercially harvested and canned or frozen for food www.bupoyesiku.net ~ 9 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

 Spores (Club moss) in making gunpowder and to create dramatic lighting effects because they can easily and quickly ignite.  Spore powder is use to coat inside of rubber gloves to enhance smooth insertion of fingers and to reduce sweat irritation  The spore powder (club moss) is used in the pharmaceutical industry to coat tablets to protect them from moisture  The herb is usually referred to as vegetable sulfur

Conclusion In this last lecture note, you have learnt how to recognize the members of pteridophytes as a group of spore producing plants.

At the end of this lecture you must have learnt how to recognize, and where to find the Pteridophytes. Focus on the usefulness, if encouraged, the use of Pteridophytes as biomonitor of environmental pollution and vegetation disturbances will be a wise decision. It can alert us of impending danger in our immediate environment.

Summary Having study this lecture note, you should:

 Have some understanding of members of pteridophytes  Have a better idea of the characteristics that separate pteridophytes from other groups of cryptogams  Be ready to get going with identification of the members on the field  Understanding contributions of pteridophytes to our lives

References/Further readings/Links

www.bupoyesiku.net ~ 10 ~ Department of Plant Science

BIO102: Plant Diversity

OLABISI ONABANJO UNIVERSITY Bup Oyesiku PhD

Test Yourself Questions (TYQ) Matric No Department Attendance-Code Session/Student’s Level

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Question TRUE FALSE

1. All pteridophytes are non-vascular plants X 2. Pteridophytes are first non-vascular seed plants X

3. Spike moss is a pteridophyte X

4. Progymnosperms is an ancestor of seed plant X 5. Fiddle heads are observed only in ferns X

6. A fern sporophyte is leafy X 7. Fern gametophyte is capable of fixing nitrogen in the soil X 8. Spores in Pteridophyte form future fertile and sterile fronds X

9. Stem of a fern is always visible ground X

10. Sexual organs in fern are found on gametophyte X

Comment:

www.bupoyesiku.net ~ 11 ~ Department of Plant Science