Plant evolution & pollinator game

Plant evolution timeline and matching plants with their pollinators
Useful information
Kit List: 

Evolution of plants: timeline on green mat, plant fossils, ginkgo leaves, set of cardboard tiles
Pollinator game: game tiles (x16) Note, all pictures with copyrights or courtesy to someone other than CHaOS were sourced from Wikimedia Commons. The remaining 3 now belong to CHaOS.
Fresh, real plant specimens may be collected beforehand.

Frequency of use: 

Evolution of plants
A lot happened to allow cyanobacteria to evolve into the wide range of land plants we see today. This timeline shows some of the main points and key developments that give rise to modern plants

Expansion of the main points on the timeline (with tile number):

Cyanobacteria – are bacteria (prokaryotes) but they can photosynthesise (1, blue-green algae)
First eukaryotes – skip this point if the children haven’t learnt about mitochondria and cholorplasts yet, if they have, explain that scientists think that eukaryotes evolved via symbiosis, with one bacteria engulfing another, but not digesting it. Chloroplasts were originally cyanobacteria engulfed by an organism that had mitochondria.
Multicellular organisms – again, may need to skip, otherwise discuss how bacteria have just one cell and that is the whole organism, whereas we have many cells, as do plants (13, anabaena) - this allows us to have specialised cells.
Primitive land plants – Explain that previously all organisms were in the water. Scientists think that the colonisation of land occurred only once, and that all land plants evolved from the Stoneworts (4, Charophyceae)
Liverworts – the first plants, still needed a lot of moisture, and live clinging to rocks in damp environments such as near waterfalls. Can be seen in Scotland still today (one is sketched on the timeline) (6)
Mosses – mosses have the first identifiable transport systems for water – xylem vessels. Can also explain the haploid/diploid thing here using standard wall moss – the green carpet part is the haploid and is the main part of the life cycle, the diploid emerges to spread spores and are on little stalks. (7)
Hornworts – developed the cuticle (which helps to reduce water loss) and stomata so are more independent of water than liverworts. All land plants except liverworts have these two features (9)
Next a true vascular system evolved that was capable of not only transporting water but also supporting the plant structurally, all other plants on land are ‘vascular’ (they have veins like us).
Club mosses – First plants to have leaves! Also developed roots which grew in the dark and needed photosynthate (sugars), so needed phloem too. (11)
Horsetails – Had a hollow stem surrounded by a ring of vascular tissue, were therefore light. Still survive today, but are much smaller than their ancestors (2)
Spore producing ferns – have proper complex leaves. Bracken, seen in most woodlands, is the most successful and widespread of all vascular plants. Reproduction is still water dependent. (3)
Then evolved all the seed plants!
Seed ferns – now extinct, but different to their surviving spore producing ancestors. See the fossils for examples, note the different leave shapes.
Cycads – the dinosaurs favourite food! We think some dinosaurs used to swallow pebbles to help them digest the tough leaves. (12)
Ginkgo – see the leaves, a living fossil in itself! (5)
Gymnosperms – mostly conifers (8). The have a novel method of growth, with an expanding ring of growing tissue round the outside of the stem. Both the largest organism and longest lived organism on Earth are conifers! Can they guess the largest? (Californian Redwood or Giant Sequoia, same tree)
200 MYA – insects evolved wings
Angiosperms (the flowering plants) – very exciting and the most diverse group of plants, still only evolved very recently (10)

Number order of photos:
1, 13, 4, 6, 7, 9, 11, 3, 2, 12, 5, 8, 10 (from most basal to most recetly evolved)

Plant fossil details:
All the fossils came from the Dover area and illustrate the horsetail point at 400 million years ago, NOTE, the ferns are seed ferns, which developed after seeds evolved, they are not the spore producing ferns we see today and evolved with the horsetails. The sketch of a horsetail on the timeline should help the children envisage what Annularia and Calamites looked like.
-Alethopteris: these are the leaves of seed fern (which are now extinct). The leaves are relatively long and thin and end in more of a point compared to neuropteris, see number 1.
-Neuropteris: also leaves of an extinct seed fern. These are the fat leaves with blunt, rounded ends, most of the leaves in the fossils are neuropteris.
-Annularia: also called Asterophyllites - don't think there is a difference. These are the leaf whorls of an extinct horsetail. (The leaves are spread concentrically about a point). There is only one of these in the fossils, next to number 3.
-Calamites: the stems of the horsetail. Can be recognised by the segmented stems. These are related to the modern horsetail. See number 2 for some well segmented ones, but also the largest one.

Ginkgo facts:
The leaves are from the Dept of Plant Sciences.
It is the species Ginkgo biloba (maidenhair tree) and has no living relatives! It even has its division (equivalent to an animal phylum). Phylum is the next classification step down from Kingdom, so to illustrate how different it is, you can explain that within the animals there are the ‘chordata’ (or vertebrates). Ginkgo is as different to a fellow plant as vertebrates are to invertebrates, e.g. tigers and insects!
Expansion of the main points on the timeline:

Major developments in the evolution of plants:

1) Multicellularity
Plants have different tissue types, like we do, so needed to be made up of more than one cell.

2) Cuticle
Once out of the water, plants needed to avoid drying out, so they evolved a waxy layer that prevented water loss (C)

3) Stomata
This waxy layer is a barrier to gas exchange – plants need carbon dioxide for photosynthesis so they evolved little openings in the cuticle to let carbon dioxide in and oxygen out (E)

4) Xylem
Plants needed to transport water from the base if they were going to be able to grow upwards, xylem allow for water transport (see coloured flowers demonstration). Xylem also provide support for upward growth as they are reinforced with lignin (G,I)

5) Phloem
Some parts of the plant are underground, and hence can’t photosynthesise, so need sugar delivered to them, phloem tubes transport these sugars (D,I)

6) Roots
Plants have had some kind of anchoring since the movement of plants onto land, initially role fullfilled by fungi, but in order to grow up, plants first had to grow down. (F)

Xylem, phloem and roots all evolved at roughly the same time, with all three features supporting each other, there is also confusion due to the limited evidence provided by the fossil record (roots particularly fossilise poorly). Leaves evolved multiple times, early leaves (microphylls) had a single vein, whilst the leaves we recognise today (megaphylls) evolved on four independant occassions (in the ferns, horsetails, progymnosperms, and seed plants)

7) Dominant sporophyte
Previously the haploid phase (like our sperm) had been the main part of the life cycle, but these need a lot of water, there needed to be a switch to the more resilient diploid (like us) in order to develop further

8) Seeds
As the world dried out 250 million years ago, plants needed to protect their ‘eggs’ and evolved seeds (A)

9) Pollen tubes
These allow the pollen to grow down to the egg and fertilise it (and can be seen in another demonstration) (B)

10) Showy flowers
Once flowers had evolved, they could be adapted to as many different forms as there were pollinators (see the pollinators game) (H)

Pollinator game
Flowers are a plant’s way of manipulating somebody else, usually an animal but sometimes the wind, into carrying its pollen around for it.
Start by asking them to think of pollinators, they’ll probably say bees. Then introduce the other forms – and show them the tiles (1-8).

A few facts:
• There are between 250,000 and 400,000 species of Angiosperms (flowering plants)
• That’s roughly a sixth of the total number of living species currently known
• Aside from the insects, the Angiosperms are the group with the most species

They are so diverse because, once you’ve mastered the ability to manipulate somebody, you can radiate into as many different sorts as there are different somebodies to manipulate.

Then ask them to match up the flower to the pollinator. Note – you may have to tell them some of their guesses are good particularly between beetle and moth as the key difference is not apparent just by looking. You may like to tell them at the start that C (the gardenia) opens at NIGHT to distinguish it from G.

More detail on the tiles:
1 = Birds (This one is a female hummingbird, species Thalurania colombica)
2 = Bees (Buff tailed bumblebee – Bombus terrestris)
3 = Beetles (pollinating beetles are small, these are Mordellidae beetles)
4 = Moths (Peppered moth – Biston betularia)
5 = Bats (Mostly fruit bats)
6 = Wind
7 = Fly (generic diptera is pictured)
8 = Butterfly (Red admiral)
A = Snapdragon (antirrhinum)
B = Grasses
C = Gardenia, note this flower has a distinctive scent at nighttime
D = Buddleia davidii (aka the butterfly plant, but that gives it away, normally call it Buddleia)
E = Red columbine
F = A Compositae flower, part of the daisy family (Asteraceae), Bellium bellidiodes
G = Magnolia
H = Jade vine, Cambridge Botanic gardens
A = 2, B = 6, C = 4, D = 8, E = 1, F = 7, G = 3, H = 5

Extra Idea for the Game (from summer tour 2013) - Make it vaguely competitive. Go through each of the different types of flowers and say what would be attracted to them. Don't go through the pollinators. Or do that vice versa. Then get them to match up the flowers to the pollinators as fast as possible. 15 second time penalty for every wrong answer. Keep track of the times for the day, as it gives this added excitement. From my vague recollection, the best time was around the 1 minute 15 second mark...

More details:

The concept of a broad association between flowers and the types of animals that pollinate them is called a pollination syndrome.

A pollination syndrome classically describes a suite of adaptations shown by a plant to a particular group of animals, usually a taxonomic order, and by those animals to a particular group of flowers, which may not be phylogenetically related to each other. The adaptations shown by the animals may be behavioural or morphological, while plants can only show morphological adaptations to animals.

Can they think of another method? There is also deceit pollination, where flowers pretend to be something, e.g. a bee in the case of some orchids. Or where flowers mimic those of another species but do not actually contain nectar so trick the pollinator into collecting pollen for free.

A = 2
Bee pollination (Melittophily)
Bees carry pollen on their bodies in a range of increasingly specialised structures from simply having hairy feet to having pollen baskets on the hind legs. Then they groom this pollen off and feed it to their larvae. Bees can see in ultra violet, blue and yellow, but not in red. They have the ability to perceive depth, and they usually have long tongues.
Bee flowers are usually quite big to bear the weight of the animal, and often have a landing platform. Bee flowers are usually brightly coloured. Yellow and blue are considered classic bee colours, but in fact many bee flowers are red despite the inability of bees to see red. The presence of UV absorbing pigments presumably modifies the red to a colour that is visible. Bees are sensitive to nectar guides, which enable them to handle the flowers more quickly by directing them straight to the nectar. Examples: snapdragon, nettles.

B = 6
Wind pollination
Wind pollinated plants do not have showy flowers, but instead have very large stamens and feathery stigmas to catch pollen from the air. This method is much less precise than using insect pollinators and requires the plants to make much larger quantities of pollen, although needs to investment in nectar (the reward to animal pollinators).

C = 4
Moth pollination (Phalaenophily)
The flowers are often white, which stands out well at night, and may close completely
during the day. The moth usually hovers alongside the flower, which is bilaterally
symmetrical with the rims bent backwards. Like butterfly flowers, moth flowers have
nectar in long tubes. Another characteristic of moth flowers is the large quantity of nectar
produced, as moths have higher energy requirements of the moth - hovering is a great deal more energy consuming than landing. Moth flowers usually attract pollinators by a strong scent, which can be quite overwhelming when the flowers open at night. Examples: gardenia, some honeysuckles.

D = 8
Butterfly pollination (Psychophily)
Butterflies usually alight on flowers, and psychophilous flowers have flat structures, held horizontal. Butterflies have long tongues, often 1 to 2 centimetres, and butterfly flowers have nectar in enclosed tubes, which can be quite deep. Butterflies have good colour vision, and can see red, so butterfly flowers are usually brightly coloured. Examples: Daisies, Buddleia.

E = 1
Bird pollination (Ornithophily)
The classic pollinating bird is the humming bird, which is American, but a variety of other groups also feed on nectar, including the African sunbirds, Australian lorikeets and American honey-creepers. Hummingbird pollinated flowers are either pendant or stand out so that there is free space for the animal to hover in. Sunbird pollinated flowers have a perch with the flower facing towards it. Bird flowers are usually either brush or tube shaped, and the nectar is secreted into spurs, which are usually shorter and wider than those on butterfly flowers. They also have to be quite tough, as a beak is both stronger and harder than a butterfly tongue. One of the key features of a bird flower is the quantity of nectar secreted. They produce very large quantities of a very concentrated nectar, so much so that it will actually drip from the flowers at certain times of the year. Ornithophilous flowers are almost always red, often with contrasting yellow markings. Unlike most insects, birds can see red, and in fact can’t see ultraviolet. Examples: red columbine, poinsettia, eucalyptus, hibiscus, passion flower.

F = 7
Fly pollination (Myiophily)
The Diptera, the fly order, show the greatest variation in methods and habits of pollination of any group of insects. Many plants flowering in adverse conditions or at odd times of the year can be entirely dependent on flies for their pollination, as they are the only group of insects which are not strictly periodic. Because they do not feed their offspring they do not require much food, and so myiophilous flowers need supply only a small quantity of nectar. Flies are more visual animals than beetles, and have a positive preference for pale and yellow colours, and for nectar guides. Fly flowers do not often have much scent but they are usually palely coloured. Examples: Umbilliferae, Compositae.

G = 3
Beetle pollination (Cantherophily)
This is widely believed to have been the first pollination syndrome, the one used by
the first Angiosperms, as the Coleoptera, the beetles, constitute one of the oldest
groups of insects and were already numerous at the time that the higher plants came
into existence. Beetle pollinated flowers provide extra pollen and nectar in a flat surface. Beetles do not have good colour vision, but rely heavily on scent. Beetle pollinated flowers are
usually greenish or off white in colour, with a strong fruity smell. Examples: Magnolia, lilies, wild roses, poppies.

H = 5
Bat pollination (Chiropterophily)
A quarter of all bat species use flowers for food to some extent. The anthers of bat flowers open at night, and the flowers often only last one night. The flowers are usually white to cream or sometimes a greenish pink colour. Bats are colour blind, so strong colours are not relevant. The main attractant is scent. Bat flowers generate a very strong scent. Bat flowers produce the most nectar of any flower type - up to 15 millilitres at a time. A few bats have become totally dependent on flowers, and eat pollen as their only protein source. The flowers have to be very large and strong, with narrow tubes or bowls from which to lap nectar. Because the bats have to find the flowers at night they are not usually within the foliage, but either hang below it for easy access or actually develop on the trunk of the plant itself. Examples: cacti, Bignoniaceae.

Risk Assessment
Date risk assesment last checked: 
Sat, 25/01/2020
Risk assesment checked by: 
Date risk assesment double checked: 
Sat, 25/01/2020
Risk assesment double-checked by: 
Beatrix Huissoon
Risk Assessment: 
Hazard Risk Affected Person(s) Likelihood Severity Overall Mitigation Likelihood Severity Overall
2m long fabric timeline Trip hazard if timeline placed on floor all 3 3 9 Place timeline on table if possible. If you have to have it on the floor, put it in a safe place – i.e. not across a likely walkway, and ensure children do not walk/run across it.
In case of injury, call first aider.
1 3 3
22 sellotaped card tiles Scratching/poking from the card tiles. all 2 2 4 Don't allow anyone to throw the tiles, keep them flat on table/floor.
In case of injury, call a first aider.
1 1 1
Specimens Possible allergic reaction and small scratches from seeds/plants/soil/leaf specimens. all 2 3 6 Ask parents if child is allergic to any of the plants before beginning the demonstration. Ensure demonstrators who are allergic do not handle the specimens. In case of adverse reaction, call a first aider. Ask public to handle specimens carefully. 1 3 3
Publicity photo: