Diversity of Plants

1. Diversity of Plants

2. Features of plants • Photosynthetic with Chlorophylls a and b and carotene accessory pigment • cellulose cell walls • carbohydrate storage as starch in chloroplast • Chloroplast structure organised into grana • mechanisms to protect the zygote

3. Evolution of plants • Evolution is driven by the need to absorb, transport and retain water, and the need to reduce the requirement of water for fertilisation.

4. The non-seed, non-vascular plantsMosses, Liverworts and Hornworts The non-seed vascular plantsWhisk ferns, Club mosses, Horsetails, Ferns Gymnosperms Angiosperms Groups of plants

5. Important today both ecologically and economically peat-burning provides part of Ireland's energy requirements, and unlike fossil fuels, peat is a renewable resource when properly managed. In addition, peatlands are the habitat of commercial crops such as blueberries and cranberries. Important in horticulture for potting and as a soil additive First colonisers of bare land Mosses, Liverworts and Hornworts

6. Mosses, Liverworts and Hornworts • No leaves • No vascular tissues • No true roots • Poorly defined cuticle • flagellated spores (sperm) • Gametophyte dominant • Sporophyte on gametophyte • Hornworts have a long lived sporophyte • Liverworts have a lobed thallus

7. Spores produced by meiosis Fertilisation of egg gives Diploid sporophyte which then divides to produce a stalk and capsule Archegonium gives single egg cell by mitosis Antheridum gives sperm by mitosis Sperm Spore (n) Female gametophyte Male gametophyte Protonoma Life cycle

8. Development of Moss from the protonoma Moss spore Developing moss plant Early protonema

9. Moss reproductive structures Archegonia with egg cell Antheridia give flagellated sperm

10. Capillary uptake of water, sufficient only for a few centimetres, restricts the height of the plant. All parts of the plant must photosynthesise as no phloem to transport sugars - no subterranean roots. Abundant water needed for germination and growth of the protonema Need a film of water for the sperm to swim in for fertilisation Non-seed, non-vascular plants and water

11. All have phloem and xylem in the stem to transport sugars and water (tracheids only) All have underground stem (rhizome) All have essentially the same reproductive system with a dominant sporophyte Whisk Ferns Club mosses horsetails ferns Seedless vascular plants

12. Whisk Ferns (Psilophytes) • No true leaves, but expanded surfaces without vascular tissue (enations) - restricts the length of the enations.

13. Microphylls (leaves with a single unbranched vascular bundle). Leaves may be long but not wide. Now rare, but in past times, tree-form club mosses more than 35 metres tall were abundant Club mosses (Lycophyta)

14. Microphylls (may be more than one parallel vascular bundle) means leaves may also be wider. Only one genus Equisetum survives today although in carboniferous times, they were abundant and tree-sized. Horsetails

15. Ferns • Megaphylls (leaves with branched vascular bundles). Leaves may be any size or shape.

16. Life cycle • Spore bearing leaves (sporophylls) produce • Spore-producing structures (sporangia) • Spores produced by meiosis • Sometimes two different sizes of spores, microspores and megaspores giving male and female prothalli, are produced from microsporangia and megasporangia. This may explain how seeds originated.

17. Spores produced by meiosis Spores germinate to give protonema N Sporophylls Archegonia develop on the prothallus Sperm released Antheridia develop on the prothallus Mature plant is sporophyte 2N Protonema germinates into a heart shaped prothallus Life cycle of Whisk ferns, Club mosses, Horsetails and Ferns

18. Phloem allows underground, non-photosynthetic parts which provide anchorage and take up water. Xylem allows the plant to grow to a great height. Plants need water for growth of the protonema/ prothallus. Need a film of water for the sperm to swim in for fertilisation Water and non-seed vascular plants

19. Gymnosperms

20. Heterospory - male and female spores are different Retention and protection of the female spores Pollination Seeds (born naked) Well developed roots 4 subgroups Conifers Cycads Gnetophyta Gnetum Welwitschia Ephedra Gingkgophyta Ginkgo biloba Gymnosperms

21. Mature plant is sporophyte 2N Seeds may have evolved by a megaspore not being shed Microsporangium gives microspores (pollen) Megaspore not shed and germinates on the plant. Megasporangium 2n gives a megaspore (n) Sporophylls Protonema germinates into a heart shaped prothallus Archegonia develop on the prothallus

22. nucellus (2n) = megasporangium Sporophyll (2n) Seed bearing scale leaf (lots of these make up a cone) Female gametophyte (n) = female prothallus = archegonium (n) Ovule = egg (n) Integuments (2N) Protective covering derived from parent (gives seed coat) Micropyle (opening to allow fertilisation) Reproduction in the gymnosperms

23. Flowers Fruits (seeds not born naked) Endosperm Xylem vessels Split into two sub-groups Monocotyledons Dicotyledons Angiosperms

24. Differences between monocots and dicots

25. Monocotyledons

26. Palms arums agaves, amaryllids, bromeliads (pineapple) yams grasses, sedges, cat-tails Irises lilies orchids gingers and bananas Families within the monocots

27. Magnoliids (Primitive flowering plants) sunflowers, scrophs, potato Ericads (Blueberries, etc.) "Lower" Hamamelids (Sycamores, etc.) "Higher" Hamamelids (Oaks, Figs, Elm, etc.) Ranunculids Rosids (Roses, Legumes, etc.) Orders within the Dicotyledons

28. Essentially the same as gymnosperms except that efficient vectored pollination. Growth of a long pollen tube to deliver the male gametes. Fertilisation occurs soon after Pollination Double fertilisation normal fertilisation to give a zygote fertilisation with 2 polar nuclei gives endosperm Developing zygote occurs within the enclosing sporophyte tissues - fruits Reproduction