Angiosperm life cycle and diversity



Carpets of spring flowers near Langebaan Lagoon. Photo: C. Voget.

The factsheet in the December issue of Veld & Flora follows on from the factsheet in the September issue, the factsheet in the June 2016 issue, the factsheet in the March 2016 issue and the Factsheets on the Classification of Life in September 2012 and Plant Classification in December 2015. (Click on the highlighted text to download the factsheets.)

Flowers separate the angiosperms from all other plants. Fossil evidence indicates that flowers evolved from spirally arranged leaves and carpels or stamens (the female and male reproductive parts of a plant) so there is some truth in the well-known quote ‘ A flower is a leaf, mad with love’. Although some angiosperm species bear female and male flowers on the same plant (monoecious) and others bear female and male flowers on different plants (dioecious), the typical hermaphrodite (male and female parts together) structure of a flower is quite different to the unisexual cones of most gymnosperms. Flowers also evolved into a myriad of different shapes and structures to tempt different animal pollinators or make use of wind and water for pollination. Like gymnosperms, flowering plants also produce seeds but these differ in that they contain an endosperm, and are entirely enclosed in protective ovaries that mature into the fruit.

A diversity of flowers

The ancestors of flowering plants diverged from gymnosperms over 200 million years ago. By 100–60 million years ago they had replaced conifers as the dominant plants on Earth. Five main groups are recognized: the Basal Angiosperms, Magnoliids, Monocots, Ceratophyllaceae and Eudicots.


Blue Waterlily (Nymphaea nouchali var. caerulea growing at Kosi Bay. Photo: Ricky Taylor, iSpot.

Basal Angiosperms are a group of the most primitive flowering plants, comprising 0.5% of living angiosperms. One of the three orders within the group include members of the Nymphaeales  which are represented in South Africa by the waterlilies.

Stinkwood Tree (Ocotea bullata) flowers. Photo: Gigi Laidler, iSpot.

Magnoliids consist of eight orders comprising 2.5% of living angiosperms today. They include our well-known Stinkwood Tree.

Aristea spiralis, a member of the Liliidae, growing at Cape Point.

Monocots share traits with magnoliids. Both arose between 130 and 125 million years ago from a common ancestor. They comprise about 28% of living angiosperms today and are classified into four superorders, one of which is the Liliidae. South Africa is particularly rich in species from this group.

Ceratophyllum demersum var. demersum growing on the lake margins in Kosi Bay. Photo: Ricky Taylor, iSpot.

Ceratophyllaceae comprises one genus Ceratophyllum with about 30 species – all of which are aquatic and lack roots and their leaves lack stomata.  They comprise 0.012 % of the world’s angiosperms. 

Halfmens (Pachypodium namaquanum) growing in the Northern Cape. Photo: C. Voget.

Eudicots have a distinctive pollen structure, but otherwise they share many traits with the preceding groups. They contain five superorders and comprise some 69% of living angiosperms. South Africa has countless plants in this group including the daisies, ericas and succulents like the enigmatic Halfmens pictured here in its desert habitat in the Northern Cape.

Bear in mind that classification of plants is in a state of flux due to ever-increasing sophistication in molecular studies and the phylogenetic tree of Plantae may well differ in some publications.

Angiosperm life cycle

Almost all land plants reproduce by means of two distinct, alternating life forms: a sexual phase that produces and releases gametes or sex cells and allows fertilisation, and a dispersal phase. The sexual phase is known as the GAMETOPHYTE or haploid (n) generation and the dispersal phase is the SPOROPHYTE or diploid (2n) generation. In angiosperms, as in all vascular plants, the sporophyte phase is the dominant generation.

The gametophyte phase is reduced to a few cells and gametophyes are totally dependent on the sporophyte. Haploid (n) microspores and megaspores (i.e. each spore has a single set of chromosomes) are produced by meoisis. Female megaspores develops into the embryo sac (megasporophyte) that grows inside the ovule, which is retained within the flower on the plant. Male microspores develop into pollen grains (microsporophtes) and are transferred to other flowers – preferably on different plants – during the pollination process. Pollen grains land on the stigma and a pollen tube grows from the pollen grain down the style, eventually reaching the ovary and entering the ovule. The male gamete or sperm (two in the case of angiosperms) then travels along the tube to the embryo sac within the ovule where it fuses with the female gamete (ovum) to form a diploid (2n) zygote (with two sets of chromosomes).

The zygote grows by cell division (mitosis) into an embryo within the seed. In angiosperms the second sperm cell fuses with the large central cell of the female gametophyte, which then develops into the endosperm, a nutrient-rich tissue which provides nourishment to the developing embryo. The seed then germinates and grows into the familiar form of the plant (the mature sporophyte). The sporophyte plants produce flowers in which the haploid (n) megaspores and microspores are produced. These have undergone a process of cell division called meiosis that results in four daughter cells each with half the number of chromosomes of the parent cell. The haploid gametophyte generation takes place within the flowers which will eventually release the diploid sporophyte seeds – and so the cycle continues.  

LINKS TO THE CURRICULUM

GRADE 11 Life Sciences, Strand 1: Diversity, Change and Continuity. Topic: Biodiversity of Plants. Content: Grouping of bryophytes, pteridophytes, gymnosperms and angiosperms.

GRADE 12 Life Sciences Strand 1: Life at Molecular, cellular and tissue level. Topic: Meiosis: the process of reduction division purposes of reduction division (gametogenesis and exceptions: mosses, ferns), Importance of meiosis: diploid to haploid: production of gametes.

Discover more about South African angiosperms by visiting iSpot http://www.ispotnature.org and PlantZafrica http://pza.sanbi.org/.
Download the factsheet by clicking here.

IMAGES for the life cycle diagram are reproduced with thanks to Alice Notten, PlantZafrica (SANBI) and The Protea Atlas Project, SANBI.

TEXT adapted by Caroline Voget from the book The Story of Life and the Environment: An African perspective by Jo van As, Johann du Preez, Leslie Brown and Nico Smit, published by Struik Nature.

Gymnosperm life cycle and diversity

The Clanwilliam Cedar (Widdringtonia cedarbergensis). Photo:Tony Rebelo, iSpot.

The factsheet in the September issue of Veld & Flora follows on from the factsheet in the June 2016 issue, the factsheet in the March 2016 issue and the Factsheets on the Classification of Life in September 2012 and Plant Classification in December 2015.

 

A DIVERSITY OF GYMNOSPERMS

The gymnosperms are cone-bearing, vascular seed plants that do not bear flowers. Their seeds develop either on the surface of scales or leaves, often modified to form cones, or at the end of short stalks as in Ginkgo. There are now only just over 1000 living species of gymnosperm, although there are many more extinct species in the fossil record. They evolved about 365 million years ago and were dominant from 245 to 65 million years ago when the angiosperms took over.  

Gymnosperms were thought to be a natural evolutionary group with one common ancestor (a clade), but with new discoveries in genetics, there is evidence to show that this is not the case. Scientists have yet to work out the evolutionary relationships, but it seems that angiosperms evolved from an extinct group of gymnosperms, although it is not clear which one is their closest relative.

By far the largest group of living gymnosperms are the conifers (pines, cypresses and relatives), followed by cycads, gnetophytes (Gnetum, Ephedra and Welwitschia) and a single living species of ginkgo. In southern Africa we have a few indigenous representatives from the conifers, cycads and gnetophytes although several others are naturalised exotics, garden plants and alien invaders.

An example of a conifer is the Outeniqua Yellowwood (Afrocarpus falcatus). Photo: Shaun Swanepoel, iSpot

Conifers (sometimes called Pinophyta) include pines,  cedars, cypressus, yellowwods, firs and redwoods which are mostly evergreen shrubs and trees with needle-like leaves. In southern Africa we have species in the family Podocarpaceae (our yellowwoods – one species of Afrocarpus and three of Podocarpus) and the family Cupressaceae (three species of cedar –  Widdringtonia  and the African Juniper (Juniperus procera).  

Encephalartos horribilis with T. rex at Kirstenbosch. Photo: C.Voget.

 

There are a hundred known species of cycad worldwide. They appeared about 320 million years ago and reached their peak in the Mesozoic Era where they existed side by side with the dinosaurs. In southern Africa we have several species of Encephalartos and one Stangeria. Having survived for so long, our cycads are seriously in danger of extinction due to human activity.

Welwitschia mirabilis. Photo: Christine Ridge-Shnaufer, with thanks to Colin Ralston, iSpot.

 

Finally, the group of gnetophytes consists of  70 know species in the three genera Gnetum and Ephedra and Welwitschia mirabilis. This group of plants has no close living relatives. Welwitschia mirabilis occurs in the Namib Desert and has evolved to cope with hyper-arid conditions. Two leathery leaves grow continuously from a cone shaped corky stem – becoming rather tattered as it ages. The leaves are grooved which collect and channel condensing fog down to the tap roots which are adapted to store moisture. Male and female plants produce cones that are pollinated by Welwitschia Beetles that only occur on the plants. A truly fascinating living fossil!

Maidenhair Tree (Ginkgo biloba) growing at Kirstenbosch. Photo: Alice Notten. For more about this tree, click here.

There is only one surviving member of the ginkgos, the  Maidenhair Tree (Ginkgo biloba) that occurs naturally in China, but they are easy to cultivate and grace many gardens, including Kirstenbosch. It remains virtually unchanged from 80 million years ago.

GYMNOSPERM LIFE CYCLE

Almost all land plants reproduce by means of two distinct, alternating life forms: a sexual phase that produces and releases gametes or sex cells and allows fertilisation, and a dispersal phase. The sexual phase is known as the GAMETOPHYTE or haploid (n) generation and the dispersal phase is the SPOROPHYTE or diploid (2n) generation. In gymnosperms, as in all vascular plants, the sporophyte phase is the dominant generation.

The gametophyte phase is reduced to a few cells – the embryo sac (female ) and the pollen grain (male). Haploid (n) microspores and megaspores (i.e. each spore has a single set of chromosomes) which are produced in male and female cones. A female megaspore develops into the embryo sac (megasporophyte) that grow inside the ovule, which is retained within the female cone on the tree. Male microspores develop into pollen grains (microsporophtes) and are transferred from the male cones onto the female cones – preferably on different plants – by wind or insects. Pollen grains enter the ovules through a microscopic gap in the ovule coat called the micropyle. Once inside, they mature further and produce sperm cells.

The gametophytes are not free living and are totally dependent on the sporophyte for water, nutrients and protection. However, no external water is needed for fertilisation to take place. Two modes of fertilization are found in gymnosperms. Cycads and ginkgos have motile sperm that “swim” to the egg inside the ovule, whereas the sperm of conifers and gnetophytes are conveyed to the embryo sac along a pollen tube that is formed inside the ovule.

Once fusion of the egg and sperm – or fertilisation – takes place, a diploid (2n) zygote forms with two sets of chromosomes. The zygote grows by cell division (mitosis) into an embryo and eventually forms the seed. The mature seed comprises the embryo and the remains of the female gametophyte, which serves as a food supply, and the seed coat. The seed then germinates and grows into the familiar form of the tree or plant (the mature sporophyte). The diploid (2n) sporophyte gymnosperm plants produce cones in which the haploid (n) megaspores and microspores are produced. These have undergone a process of cell division called meiosis that results in four daughter cells each with half the number of chromosomes of the parent cell. The haploid gametophyte generation takes place within the female cones which will eventually release the diploid sporophyte seeds – and so the cycle continues.  

READ MORE

Articles in back issues of Veld & Flora include “The aerodynamics of wind pollination” by Hans Nieuwmeyer vol 88(2), p.73; “Saving the Clanwilliam Cedar“ by Penny Mustart, vol 99(4), 184-186; “The Cycad Amphitheatre” by Alice Notten, vol. 99(4), 178-179 and “The Winterberg Cycad” by John Donaldson vol 81(2), 36-39. Discover more about South African gymnosperms by visiting iSpot – and searching for ‘gymnosperms’, or PlantZafrica – and searching for Widdringtonia, Podocarpus, cycad and Welwitschia, or Wikipedia.

 LINKS TO THE CURRICULUM

GRADE 11 Life Sciences, Strand 1: Diversity, Change and Continuity. Topic: Biodiversity of Plants. Content: Grouping of bryophytes, pteridophytes, gymnosperms and angiosperms.

GRADE 12 Life Sciences Strand 1: Life at Molecular, cellular and tissue level. Topic: Meiosis: the process of reduction division purposes of reduction division (gametogenesis and exceptions: mosses, ferns), Importance of meiosis: diploid to haploid: production of gametes.

PHOTOGRAPHS for the gymnosperm life cycle diagram are reproduced with thanks to Alice Notten and PlantZafrica (SANBI) for the images of the male and female cones and seeds of the Clanwilliam Cedar (Widdringtonia cedarbergensis ) and to Anthony Hitchcock and iSpot for the use of the image of the Clanwilliam Cedar. 

TEXT adapted by Caroline Voget from the book The Story of Life and the Environment: An African perspective by Jo van As, Johann du Preez, Leslie Brown and Nico Smit, published by Struik Nature and also online sites including Iziko Museum’s website and Wikipedia.

Fern life cycle and diversity

Blechnum attenuatum and other ferns growing on Montagu Pass in the Western Cape. This is the sporophyte phase of the fern life cycle. Photo: Diane Turner, iSpot.

The factsheet in the June 2016 issue of Veld & Flora follows on from the factsheet in the March 2016 issue of Veld & Flora, vol. 102(1), and the Veld & Flora Factsheets on the Classification of Life in vol. 98(3) September 2012 and Plant Classification in vol. 101(4) December 2015.


Fern leaves with sori. Photo: Clare Archer, iSpot.

 A DIVERSITY OF FERNS

Ferns or Pteridophytes are a group of primitive plants. It includes the familiar fern with its graceful fronds, but also encompasses a great diversity of fern-like plants that grow in a variety of habitats from shady, damp forests to deserts. Like Mosses and Liverworts (Bryophytes) they have no seeds, flowers or fruit, and reproduce by means of spores. They mostly grow on dry land but they still need water in order to reproduce. Unlike Bryophytes they have a vascular system (specialized tissue for transporting water and nutrients – xylem and phloem).

Ferns are usually referred to as Pteridophytes, which includes all spore-bearing, vascular plants. In older classifications these plants were informally divided into ‘true ferns’and ‘fern allies’. The ‘fern allies’ comprised the Clubmosses, Spikemosses, Quillworts, Whisk Ferns and Horsetails. New research in molecular biology has necessitated a few changes in fern classification. To reflect evolutionary relationships more accurately, scientists now propose to divide spore-bearing, vascular plants into two formal groups: Lycophytes and Monilophytes.

Lycophytes include the Clubmosses, of which there are three genera in southern Africa: Huperzia, Lycopodiella and Lycopodium, Spikemosses which contain a single genus Selaginella with ten species in southern Africa and the Quillworts, which also contain a single genus, Isoetes, with at least 14 species in southern Africa. This ancient group of plants was once prolific with extinct giant species of Clubmosses growing up to 40 m high.

Monilophytes include the Snaketongue Ferns of which one genus, Ophioglossum, is indigenous to southern Africa, Whisk Ferns of which one species, Psilotum nudum, is indigenous to southern Africa, the Horsetails of which one species, the African Horsetail (Equisetum ramosissimum), is indigenous to southern Africa, the Potato Ferns of which only one species, Ptisana fraxinea, is indigenous to southern Africa, and the Leptosporangiate Ferns, which is the largest and most diverse group that contains around 270 species indigenous to southern Africa.

The African Horsetail (Equisetum ramosissimum subsp. ramosissimum var. altissimum) is the only species of horsetail in South Africa. The spores are borne under sporangiophores in the cone-like structures at the tips of some of the stems. Photo: Clare Archer, iSpot.

Almost all land plants reproduce by means of two distinct, alternating life forms: a sexual phase that produces and releases gametes or sex cells and allows fertilisation, and a dispersal phase. This is an adaption which frees plants from a life under water and allows them to live and reproduce on dry land. The sexual phase is known as the GAMETOPHYTE or haploid (n) generation and the dispersal phase is the SPOROPHYTE or diploid (2n) generation.

In ferns, the dispersal phase culminates in the production of haploid (n) spores (i.e. each spore has a single set of chromosomes) which are released from capsules (sporangia) borne on the underside of fern leaves. These spores germinate and grow into tiny, free-living plants –the prothallus. This is the sexual (or gametophyte) generation of the fern plant. Haploid (n) sexual cells or gametes are formed in the sex organs (the antheridia and archegonia) on the underside of the prothallus. The male gametes (sperm) then swim towards the female gametes (eggs) in the archegonia of the prothallus. Thus, even though ferns mostly grow on land, they still need the presence of water to facilitate fertilisation. Once fusion of the egg and sperm – or fertilisation – takes place, a diploid (2n) zygote forms with two sets of chromosomes. The zygote grows by cell division, in a process called mitosis, into the dispersal (or sporophyte) generation of the fern plant which is the familiar fern that we see growing all about.

The diploid(2n) sporophyte fern plants produce sporangia or capsules on the undersides of their leaves in which haploid (n) spores are produced. The black dots we normally see on the leaf are sori (singular sorus) which are clusters of sporangia. The spores inside the capsules have undergone a process of cell division called meiosis that results in four daughter cells each with half the number of chromosomes of the parent cell. The spores are dispersed and germinate and grow into haploid gametophyte plants – and so the cycle continues.

So although the gametophyte (n) and sporophyte (2n) are two different plants, in ferns the sporophyte is what we see and know as a fern. This is different to the life cycle of mosses, conifers and flowering plants, which are covered in previous and subsequent factsheets.

Some ferns dispense with the sexual phase of the cycle and reproduce vegetatively. See ‘The ferns of the Ntendeka Wilderness’ in Veld & Flora 67(4), 118-120, December 1981.

READ MORE
In the 1981 issue of Veld & Flora, read about ‘The ferns of the Ntendeka Wilderness’ Veld & Flora 67(4), 118–120. In the 1998 issue, read about ‘The ferns of Mariepskop’ Veld & Flora 84(4) 116-117. In the 1994 issue, read ‘The weedy ferns of Ferncliffe: Unusual invaders threaten Natal’s flora’ Veld & Flora 80(3), 88-90.
'To be or not to be a fern ally' by Ronell and Arrie Klopper, Pteridoforum 80: January 2007.

Discover more about South African ferns by visiting iSpot –  and searching for ‘ferns’ or Wikipedia.

LINKS TO THE CURRICULUM

GRADE 11 Life Sciences, Strand 1: Diversity, Change and Continuity. Topic: Biodiversity of Plants. Content: Grouping of bryophytes, pteridophytes, gymnosperms and angiosperms.

GRADE 12 Life Sciences Strand 1: Life at Molecular, cellular and tissue level. Topic: Meiosis: the process of reduction division purposes of reduction division (gametogenesis and exceptions: mosses, ferns), Importance of meiosis: diploid to haploid: production of gametes.

TEXT by Caroline Voget with assistance from Dr Ronell R Klopper, South African National Plant Checklist Co-ordinator, SANBI. The following books and websites were consulted: The Story of Life and the Environment: An African perspective by Jo van As, Johann du Preez, Leslie Brown and Nico Smit, published by Struik Nature and also from online sites including: Iziko Museum’s website, the Online Textbook, Prentice Hall, Wikipedia and The Encyclopaedia of Life.

Bryophyte life cycle

What we see and know as moss is the gametophyte form of the moss plant.

The factsheet in the March 2016 issue of Veld & Flora, vol. 102(1), follows on from the Veld & Flora Factsheets on the Classification of Life in vol. 98(3) September 2012 and Plant Classification in vol. 101(4) December 2015.

Understanding the alternation of generations

The way that almost all land plants reproduce is by means of two distinct, alternating life forms, a sexual phase that produces and releases gametes or sex cells and allows fertilisation, and a dispersal phase – both of which are adaptations to an essentially waterless environment. The sexual phase is known as the GAMETOPHYTE or haploid (n) generation and the dispersal phase is the SPOROPHYTE or diploid (2n) generation.

Mature gametophyte plants produce haploid sex cells (egg and sperm) in sex organs (the male antheridia and female archegonia). These sex cells (also called gametes) fuse during fertilisation to form a diploid (2n) zygote which grows, by means of mitosis (that results in two daughter cells each having the same number and kind of chromosomes as the parent cell), into a new sporophyte plant.

The diploid sporophyte produces haploid (n) spores (i.e. each spore has a single set of chromosomes) by means of the process of cell division called meiosis. Meiosis results in four daughter cells each with half the number of chromosomes of the parent cell. The spores are dispersed and eventually germinate and grow into haploid gametophyte plants – and so the cycle continues

 

Coping out of water

Bryophytes, which include moss, are primitive plants that give us some idea of how the first plants that ventured onto land coped with their new waterless environment. They share many features with other plants, but differ in some ways – such as the lack of an effective vascular system (specialised tissue for transporting water and nutrients – xylem and phloem) which distinguishes them from ferns, conifers and flowering plants. They usually form low-growing, dense cushions on rocks, the bark of trees, and other surfaces including buildings. The plants absorb and lose water depending on their surroundings and they need a film of water in which to reproduce as the sperm need to swim from the male reproductive organs to the eggs in the female organs.

 

Bryophyte life cycle

 

The diagram above shows the life cycle of a typical moss. What you see growing on rocks at Kirstenbosch, or on damp walls on your house, is the gametophyte form of the moss plant. Sexual cells or gametes are formed by male and female gametophyte plants – and the male gamete or sperm needs water in which to swim towards the female eggs in the archegonia of the female plants (see photo below).

In the tufted moss Polytrichum the male sex organs (antheridia) occur within a whorl of leaves and discharge sperm into the water-filled, reddish splash caps. From there raindrops splash the sperm cells onto nearby female plants. Photo: Chris Vynbos, iSpot

Once this occurs, and fusion takes place, a diploid zygote forms with two sets of chromosomes. The zygote develops into the sporophyte which is a stalk growing out from the gametophyte plant that supports a sporangium or capsule in which spores are produced (see photo below).

In bryophytes the sporophyte plant is a stalk growing from the gametophyte plant. The stalk supports a sporangium that produces spores which give rise to new gametophyte plants. Photo: Sally Adam.

The spores are dispersed and grow into the new gametophyte generation. So, although the gametophyte and sporophyte are two different plants, in mosses the sporophyte is always attached to the gametophyte. This is different to the life cycle of ferns, conifers and flowering plants which will be covered in subsequent factsheets.

Download the Factsheet on the Classification of Bryophytes (shown above) here.
Download the Factsheet on The Classification of Plants (above) here.
Download the Factsheet on The Classification of Life here.
Download these articles that are relevant to the study of the classification of moss:
Cocks, Martin 1996. Surviving at the edge of life: The tiny plants that eke out an existence on the frozen continent. Veld & Flora 82(2), p. 46–48.
Online textbook - Bryophytes (Prentice Hall).
Josh Hall Educreations UTube video on Moss and Liverwort lifecycles.

The Green Kingdom

All living organisms, from bacteria to baobabs, share certain features. They all replicate using DNA, and can convert the information stored in DNA into products for building cellular machinery using fats, proteins and carbohydrates. Scientists work out the relationship between all living things by comparing outward appearances, and more importantly, microscopic cellular composition, and grouping evolutionarily close organisms together on an evolutionary or phylogenetic tree. At the base of the tree is the ‘Last Universal Common Ancestor’ and at the very tips are the twigs which represent all species – living and extinct. The Veld & Flora Factsheet in the September 2012 issue of Veld & Flora, vol. 98(3) outlines the basics of classification of biodiversity in which all life forms are grouped into three Domains – Archaea, Bacteria and Eukarya, the latter containing five Kingdoms – Protozoa, Chromista, Plantae, Fungi and Animalia. Be aware that classification schemes are constantly changing and shifting as new discoveries are made, especially in the ‘nano-world’. In this factsheet we zoom in on plants and show how they are grouped within the Kingdom Plantae and placed on the phylogenetic tree according to shared characteristics that reflect evolutionary relationships.

The Kingdom Plantae
The most important feature of plants is their green colour, which is the result of a group of pigments called chlorophyll. Plants use chlorophyll to capture light energy, which fuels the manufacture of food in the form of carbohydrates.
Plant life cycles all include an alternation of generations (a haploid-diploid life cycle). Most plants are terrestrial.
The first plants seem to have evolved from the green algae which have enough physiological features of photosynthesis in common with modern plants to indicate this. One group of green algae, the charophytes (which includes Spirogyra), is more closely related to plants than to the other green algae
The fact that all plants have stomata except the Hepaticophyta (liverworts) suggests that liverworts were the earliest group to diverge. Other features used to distinguish different groups within the plant kingdom and work out their evolutionary relationships are reproductive strategies (spores, seeds, cones, fruits or flowers, sexual or asexual reproduction), and the presence or absence of features such as vascular tissue (specialized tissue for transporting water and nutrients – xylem and phloem) and leaves and roots.

Download the Factsheet on The Classification of Plants (above) here.
Download the Factsheet on The Classification of Life here.
Download these articles that are relevant to the study of plant classification:
The cycad amphitheatre at Kirstenbosch by Alice Notten, Veld & Flora 99(4), 178-179.
From crags to riches: Why is the flora of the Drakensberg alpine centre so diverse by Clinton Carbutt.
The art of plant identification by Wendy Hitchcock, Veld & Flora 100(2), 60-61.
Surviving at the edge of life: The tiny plants that eke out an existence on the frozen continent, by Martin Cocks, Veld & Flora 82(2), 46-48.
The all-blue agaric: a new record for South Africa by Clinton Carbutt and Marieka Gryzenhout,,Veld & Flora 97(2), 84-85.
Of sea lettuces and green sea intestines: Common intertidal green seaweeds of the Cape Peninsula, Veld & Flora 86(3), 124-125.
Welwitschia mirabilis by Ernst van Jaarsveld, Veld & Flora 86(4), 176-179.
A very useful phylogenetic tree of life from the excellent book The story of life and the environment: An African perspective by Jo van As, Johan du Preez, Leslie Brown and Nico Smit, published by Struik Nature.
Green Algae: The nexus of plant ancestry from ScienceDaily, 12 October 2007.

The photo above shows a moss growing on soil on Table Mountain.

Nature at your service

 "Nature’s services will help the younger generation to understand the benefits we gain from ecosystem services, but equally the joy and pleasure they can give us if we treat them with knowledge, respect and wisdom." (WWF)

Ecosystem services are the functions of the ecosystem - the living and non-living elements of our natural environment - that benefit humans. The services we receive ‘free’ from nature include: fertile soil for our food to grow in, a comfortable climate that supports human life, clean water to drink, pollinating insects and natural wonders for humans to appreciate. Plants, animals and micro-organisms perform a myriad of tasks that we depend on for our survival and prosperity. Most ecosystem services are impossible to replace with technology.

Scientists place these services into four main categories – supporting, provisioning, regulating and cultural, although there is considerable overlap.

Discover how scientists are trying to work out the value of these vital services to humankind so that we will protect them. Download the Veld & Flora factsheet on Ecosystem Services here.

LINKS TO THE CURRICUCUM
Grade 10, Life Sciences Strand 3: Environmental Studies, Topic: Biosphere to Ecosystems.

Grade 11, Life Sciences: Strand 1: Diversity, Change and Continuity, Topic: Biodiversity and classification of micro-organisms. Strand 3: Environmental Studies, Topic: Human impact on the environment: Current crises for Human survival: problems to be solved within the next generation.

READ MORE

Many articles in past issues of Veld & Flora will be relevant to this topic as understanding ecosystem services requires a knowledge of basic ecology, which describes the underlying principles and interactions of organisms and the environment. Some relevant articles include:

Flower picking on the Agulhas Plain: Seeking a balancebetween economic and ecological sustainability by Heather D’Alton, Veld & Flora March 2014, pages 10–11.

Honey Bee Forage plants: how can you help? by Mbulelo Mswazi & Carol Poole, Veld & Flora June 2015, pages 82–83.

How no-man’s-land is now everyone’s problem: the renowned Cape flora is everywhere in retreat as runaway pine invasions transform the Outeniqua and Tsitsikamma mountains by Richard Cowling, Brian van Wilgen, Tineke Kraaij & Jonathan Britton, Veld & Flora September 2009, pages 147–149.

Rooibos: refreshment for humans, bees and wasps by Sarah Gess, Veld & Flora March 2000, pages 19–21.

The ecological economics of fynbos ecosystems by Steven I. Higgins & Richard M. Cowling, Veld & Flora March 1997, pages 4–5.

Wildflower farming on the Agulhas Plain: Should we be concerned? by Martina Treurnicht, Karen Esler & Mirijam Gaertner. Veld & Flora September 2010, p 138–139.

Internet reading

Exploring ecosystem-based adaptation in Durban, South Africa: ‘learning-by-doing’ at the local government coal face by Debra Roberts, Richard Boon, Nicci Diederichs, Errol Douwes, Natasha Govender, Alistair Mcinnes, Cameron Mclean, Sean O'Donoghue and Meggan Spires. 2012 24: 167 originally published online: 2 December 2011  in Environment and Urbanization.

TEEB website.  

Hot facts about fire

“Fire has been a neglected process in Earth’s history and now it is time to reassess its role in shaping our world.” Andrew C. Scott

Fires are usually seen as disasters that destroy ecosystems, but they are actually ecological processes that influence structure and function in ecosystems, particularly among plant communities. Scientists have shown that fire may have been the catalyst for the evolution and expansion of flowering plants (angiosperms) during the Cretaceous period. Similarly, the expansion of C4 grasses during the Miocene was probably facilitated by fire in extensive seasonally dry areas. These studies have contributed to an increasing recognition that fire has been an ancient process on Earth.

  Fynbos in the south-western Cape depends on regular fires in seven to thirty year cycles to ensure that old plant communities make way for new growth. Grasslands also need fire to prevent encroachment by shrubs and trees. Fire is commonly used in Africa for managing different ecosystem types (albeit sometimes to the detriment of the ecosystem as in the case of forests being cleared for agriculture). As Earth’s climate is rapidly changing, we urgently need a better understanding of the way in which fire shapes the landscape in order to plan for the future of the human species.

Discover what the Firestarters are, why fire is An Open and Shut Case, how plants need to Adapt or Fry and meet some Fireflowers. Download a pdf of the factsheet here.

LINKS TO THE CURRICULUM

Life Sciences Grade 10, Strand 3, Environmental Studies. Content: Environment and Ecosystems.

READ MORE

Firestorms in savanna and forest ecosytems: Curse or Cure? by Catherine Browne & William Bond, Veld & Flora 97(2), pp. 62–63, June 2011.

Why do grasslands have no trees? by Julia Wakeling, William Bond & Michael Cramer, Veld & Flora 96(1), pp. 24–25, March 2010.

The long walk to treedom: A tale of the African savanna by Glenn Moncrieff, Veld & Flora 96(1), pp. 22–23, March 2010.

The devil of a job: Ecological restoration trials on Cape Lowland renosterveld by Penelope Waller, Veld & Flora 100(3), pp. 132–134, September 2014.

Where there’s smoke, there’s seed: Plant-derived smoke is an important natural ‘cue’ for the germination of fynbos seed by Neville Brown, Philip Botha, Deon Kotze and Hanneke Jamieson, Veld & Flora 79(3) pp. 77–79, September (1993).

Misunderstood: Our grasslands are ancient stable features with a rich assemblage of plants and not just an early stage in the formation of forests by Nicholas Zaloumis. Veld & Flora 97(2), pp. 68–70, June 2011.

Life after death in fynbos: The story of fire and seeds by Penny Mustart, Veld & Flora 86(2), pp. June 2000.

Some readers letters on the topic of fire, Veld & Flora June 2015.

Good books:

The Story of Life & the Environment: An African perspective by Jo van As, Johann du Preez, Leslie Brown and Nico Smit, Struik/Nature, 2012

Internet reading:

The article Fire and the spread of flowering plants in the Cretaceous by William J. Bond & Andrew C. Scott in New Phytologist 188, 1137–1150, 2010

The SANBI website PlantZAfrica.
 

The evolution of African plant diversity by H. Peter Linder, Frontiers in Ecology and Evolution.

Fire and plant evolution: MEDECOS Special Session on ‘Fire as an evolutionary pressure shaping plant traits’ New Phytolotist.