Plants

1. Plants C. Bustamante, M.Covington, M. Santistevan, A. Urias, & R. White

2. Introduction • 1950’s classification • two kingdoms: plants and animals • Advancement of Technologies = ability to discern more subtle, yet profound differences in the living world • New 5-kingdom model evolved

3. Introduction continued… • Based on the 5-kingdom / 2-superkingdom model • plants belong to the superkingdom Eukarya and the kingdom Plantae • (Some authors differ about the definitions of the largest taxons placing Bacteria and Archaea on an equal footing with Eukarya)

4. Introduction continued… • Distinction of plants from other organisms • life cycles rather than by their capacity for photosynthesis • few plants (beech drops, Epifagus,) are heterotrophs, lost green pigment in the course of evolution and derive their organic material from other organisms • majority are photosynthetic autotrophs, use solar energy, atmospheric carbon dioxide, water, inorganic materials to synthesize organic compounds • dominant contribution: • food, fiber, coal, oil, wood and other forms of stored energy that sustain the rest of the biota, maintain oxygen in the atmosphere

5. Plant reproduction has the distinguishing characteristic of alternating generations of diploid (double-chromosome) sporophytes and haploid (single-chromosome) gametophtyes, illustrated here for a fern.

6. Introduction continued… • Some photosynthetic organisms once classified as plants due to color and sedentary habit no longer considered plants because they lack embryos and other criteria for plant classification • Cyanobacteria (blue-green algae), • green algae • lichens (fungi with bacteria or protoctist symbionts

7. Introduction continued… Differentiation • Though cyanobacteria and plants utilize chlorophylls, greenish pigments, that capture the energy of sunlight • And Cyaobacteria were architects of the earth's atmosphere through aquatic and photosynthetic characteristics, • it was the plants, which emerged to produce and maintain land-based life on the earth

8. Introduction continued… • All plants, algae, and cyanobacteria that photosynthesize contain chlorophyll “a” • There is also chlorophyll "b", which occurs only in "green algae" and in the plants

9. Introduction continued… • To date there are some half-million species of plants identified – new ones found each year. • Oldest fossils-430 million years old in the Phanerozoic eon • Have aquatic ancestors • appear to have evolved from only a small group of green algae

10. Plant Evolution • Prerequisites for survival • sunlight for energy, • air for carbon dioxide, • crucial inorganic nutrients, and • water • Coping with life on the land • Sunlight, air, and nutrients readily available • Need for water to support metabolism and reproduction drives evolution

11. Plant Evolution continued… • 12 plant phyla divide into two major groups • 3 phyla of non-vascular plants (Bryata or, informally, bryophytes) and • 9 phyla of vascular plants (Tracheata or tracheophytes) • Bryata are most closely related to plant ancestors among the green algae (Chlorophyta)

12. Non-Vascular Plants (Bryata) • The three Bryata phyla are • Hepatophyta (liverworts) • Anthocerophyta (horned worts) • Bryophyta (mosses)

13. Non-Vascular Plants (Bryata) • Bryophytes differ from vascular plants lacking vascular tissue • plant body is typically a low-growing organism that lacks differentiated leaves, stem, and roots • Absorb nutrients directly from the environment, anchoring to soil, tree bark, and rock via rootlike structures called rhizoids • in contrast to the vascular plants, the dominant phase of the lifecycle is the gametophyte phase

14. Non-Vascular Plants (Bryata) continued… • Bryophyte sperm have undulipodia (flagellae) that enable them to swim to the female gametophyte, but require fresh water to bear them to the egg • They may also exhibit asexual reproduction, by fragmentation • Uses of Bryata • moisture-holding capacity of soils, and • when dried, used as fuel

15. Vascular Plants (Tracheata) • Non-seed-bearing (4 phyla) • All reproduce by means of spores rather than seeds • Seed-bearing (5 phyla) • “Naked” seeds (Gymnosperms; 4 phyla) • Seeds enclosed in the fruits of flowers (Angiosperms) • Contain lignified fluid-conducting vessels • Two kinds of vascular cells • Xylem carries water and minerals from the roots to the rest of the plant • Phloem transports photsynthate to other tissues

16. Seedless Vascular Plants • Four Phyla • Lycophyta (club mosses) • Psilophyta (whisk ferns)

17. Seedless Vascular Plants continued… • Four Phyla • Sphenophyta (horsetails) • Filicinophyta (ferns).

18. Seedless Vascular Plants continued… • The earliest seedless vascular plants lacked differentiation of tissues between root and shoot, and between stem and leaf. • The evolution of these tissues enabled plants to reach great sizes. • In all vascular plants, the sporophyte is the dominant life-cycle phase.

19. Seedless Vascular Plants continued… • Some uses include • lubricants • fireworks • medicines • Some are edible for humans, but poisonous to livestock. • Ferns provide food, thatch, tea, dyes, medicines, and even pillow stuffing.

20. Gymnosperms (Naked seeds) • A seed is a mature ovule enclosing an embryo and stored food within a durable coat. • It provides enormous advantages in survival over freely dispersed spores. • Gymnosperms, like seedless plants, are heterosporous. • i.e., sharp differences between male microspores (pollen grains) and female megaspores • They include 5 orders, 15 families, about 70 genera, and 730 species.

21. Gymnosperms (Naked seeds) continued… • Four gymnosperm phyla are • Cycadophyta (cycads), • Ginkophyta (represented by the a single surviving species Ginkgo biloba), • Coniferophyta (conifers), and • Gnetophyta (gnetophytes),

22. Gymnosperms (Naked seeds) continued… • Seed production evolved by at least 360 million years ago. • extinct progymnosperms produced seeds, but no flowers or fruits • Cycad cones exhibit an early (possibly the earliest) animal pollination system, attracting insects with odors and heat

23. Gymnosperms (Naked seeds) continued… • Cycads - palm-like, but not true palms • live in the tropics and subtropics; are listed as endangered species • uncooked seeds are toxic to humans and livestock, • cooked seeds are edible • leaves are used as thatch and dressing for wounds

24. Gymnosperms (Naked seeds) continued… • Ginkgo- leaf veins that split into two smaller veins • edible; • leaf extracts have found medicinal uses

25. Gymnosperms (Naked seeds) continued… • Confers — largest gymnosperms • Uses include • lumber and other wood products • pulp, • resin products, • edible seeds, and • medicinal

26. Gymnosperms (Naked seeds) continued… • Gnetophytes – live in a wide variety of regions • Namibian Desert, • North America, • Mediterrenean, and • Himalayas to Mongolia • Uses include: • Medicinal, and • Limited as food

27. Angiosperms (flowering fruit bearing) • Anthophyta – the most abundant plants • produce flowers, wherein fertilized eggs become seeds surrounded by nutrient-bearing fruits • include plants as grasses (e.g. corn, wheat, barley), lilies, daffodils and palms • Flowers may be single or clustered • reproductive elements of the flower are the stamen and the pistil

28. Angiosperms (flowering fruit bearing)continued… • Provide the basis for most human foods and the source of most pharmaceuticals.

29. Plant Relationships • Plants occur in many ecosystems and adapt to climate and precipitation, elevation, and soil types. • Plant communities that are found over large areas are referred to as biomes.

30. Plant Relationships continued… • Plants provide (living) structure to the ecosystem as • cover soil (grass), • middle canopy (shrubs), • upper canopy (trees) • And additional surface area as • roots, leaves, stems, branches, and trunks • Which it provide a means of exchange for materials and energy as well as habitat for other organisms

31. Plant Relationships continued… • Biodiversity - amount of different kinds of living organisms in an ecosystem • Can also be described • by the differences between individuals of the same species (intraspecific diversity). • Studies show that stability of an ecosystem is positively related to the diversity present.

32. Plant Relationships continued… • Plants are producers in ecosystems. • Autotrophs –produce their own food. • Derive energy from the sun • Convert atmospheric carbon into sugar (photosynthesis). • Consumers get their energy from consuming producers. • Carbon is the basis of life on Earth and is largely made available to the other kingdoms by the plants. • Plants provide carbon in the form of dead plant matter (shed leaves, needles, stems, twigs, rotting trunks, etc.) to the soil environment

34. Plant Relationships continued… • Plant respiration produces oxygen! • Oxygen is central to the metabolism of the other kingdoms, especially the animal and fungi kingdoms. • Integral with the production of biomass, plants require sugar to provide energy for growth, defense, and reproduction.

35. Plant Relationships continued… • Herbivory • primary producers and provide the basis for secondary productivity (herbivory or grazing) • Energy relationship between primary and secondary producers may differ by an order of magnitude (i.e., as little as 10% of the biomass consumed becomes biomass for the consumer). • Plants are central to the survival of consumers by the transfer of biomass

36. Plant Relationships continued… • Herbivory continued… • plants also provide nitrogen. • although the atmosphere is largely composed of nitrogen (79%), the gaseous phase of nitrogen (N2) is not available to living systems • nitrogen pathways are complex and mediated by a plethora of bacteria species. • Nitrogen, fixed by bacteria and assimilated by plants is available to other kingdoms by grazing (animals) or decomposition (bacteria and fungi).

37. Nitrogen Cycle

38. Nitrogen Cycle

39. Water Cycle

40. Plant Relationships continued… • Plant Communication • Respond to light, gravity, nutrients, and touch • Signal via sight, smell, touch, and chemical signals

41. Plant Relationships continued… • Disturbance and Succession – unable to move • Disturbances can be any event that drastically alters the structure and function of an ecosystem such as fires, floods, landslides, or any other natural (or unnatural) disaster. • Plants will begin to reestablish themselves in the cleared area by a process of succession.

42. Plant Relationships continued… • Co-evolution • wind, earth, fire, and water are central to the survival of plants and other kingdoms • Many plant species would not be able to continue without the relationships with other organisms • bacteria and worms are central to maintenance of fertile soils and process organic matter • Animals are important to seed germination and dispersal • Mycorrhizal fungi connect roots of the plant • Human agriculture

43. Conclusion • Plants are primary producers in terrestrial ecosystems • Convert abundant sunlight, carbon dioxide from the atmosphere, plus water and minerals from the soil, into energy-bearing food for organisms in all the other kingdoms.

44. Plant Evolution continued… • Vascular plants divide further • non-seed-bearing (4 phyla) and • seed-bearing (5 phyla), with seed bearing • fossil record includes extinct plant phyla Zosterophyllum and Rhynia with the oldest vascular plants, the lycopods (club mosses)