1. UNIT 9: PLANTS Chapters 22-24

3. Earliest Plants Algae Phytoplankton Lived in the sea

4. Problems with life on land Problem Drying Out Making Food Reproduction Gravity & Support Getting water & nutrients Solution Waxy cuticle, stomata Formed leaves Develops spores & seeds Bark (cork) & vessels Roots & vessels

5. Types of Plants Avascular – Bryophytes – nonseed plants Tracheophytes – vessels for transport and support

6. Mosses & Liverworts: The Bryophytes

7. First land plants AVASCULAR = very small 500 m.y.a. Must grow in moist environments Used for fuel (peat)

8. Reproduction in Bryophytes Mosses have a protonema (liverworts do not) Sexual reproduction – Antheridium – makes sperm – Archaegonium – makes eggs Asexual reproduction – Fragmentation – Formation of gemmae

9. Peat moss is also used in gardening. Gardeners add peat moss to the soil because it improves the soil's ability to retain water. Peat moss also has a low pH, so when added to the soil it increases the soil's acidity. Some plants, such as azaleas, grow well only if they are planted in acidic soil.

10. Tracheophytes Vessels – XYLEM = transports water & dissolved minerals from roots to leaves – PHLOEM = transports sugars from leaves to rest of plant Spores or seeds for reproduction

11. Vascular tissue conducts water and nutrients throughout the plant body.

12. Club Mosses (Lycophyta) Leaves produce spores – Strobilus = spore-bearing leaves – Prothallus = produces antheridia & archaegonia

13. Horsetails (Sphenophyta) Jointed stems Reproduction similar to club moss

14. Ferns (Pterophyta) 400 m.y.a. Dominant form = sporophyte Structure – Rhizome = underground stem – Fronds = leaves – Sori = store spores on underside of fronds

15. Gymnosperms Gymno = “naked” Sperm = “seed” First plants to produce seeds – No flowers – No fruit

16. Conifers These longleaf pines in North Carolina grow in an area that receives abundant rainfall. Yet water sinks quickly through the sandy soil, limiting the availability of water to tree roots. In this environment, the pines' water-conserving needles are an adaptation that contributes to the trees' survival.

17. Why Make Seeds? Has own food supply Protective coat against harsh conditions Some are designed for travel to new areas

18. Sporophytes produce: MICROSPORE – Produce male gametophyte – Produce pollen MEGASPORE – Produce female gametophyte – Produce ovule (makes archaegonia with egg cells)

19. Gymnosperm Reproduction Pollen grains carried by wind Land on ovule, develop pollen tube Sperm move through tube to fertilize egg – Fertilized egg = ZYGOTE – EMBRYO = young, diploid sporophyte plant – COTYLEDONS = food storage for embryo, become first leaves

20. Why Pollen Instead of Spores? Plant can live in very dry areas Fertilization does not require water Pollen has protective coat and food supply for sperm

21. Why Ovules Instead of Archaegonia? Protective tissues prevent drying out Ovule holds archaegonia and protects eggs from elements

22. Minor Gymnosperm Groups Cycadophyta (1 st in Triassic Era) Ginkgophyta – Only one species today Ginkgo biloba – Most lived 200 m.y.a. Gnetophyta – only three genera – Gnetum – house plants – Ephedra – weight loss, allergies & asthma – Welwitschia

23. Coniferophyta (largest group) Needle or scale-like leaves Bear seeds in woody cones Can live in very cold climates Most are evergreens Have wood – Made of thick-walled vessels (TRACHEIDS) – Tracheids are xylem

24. Angiosperms Angio – “flower” Sperm – “seed” Extremely diverse All have seeds enclosed in fruit

25. Angiosperms develop unique reproductive structures known as flowers, which contain ovaries that surround and protect the seeds. Apple flowers produce seeds inside ovaries, which mature into fruits.

26. Cambium Any growth tissue in plants Types of cambium – Vascular = produces xylem & phloem – Cork = produces cork (bark)

27. Overall Structures [121] Roots Stems Leaves Flowers

28. Roots [124] Absorb water & nutrients Hold plant in place Root types: – Fibrous – Tap – Prop – Aerial

29. Stems [123] Support leaves & flowers Sometimes photosynthesis Transport (contain xylem & phloem) Types – herbaceous – green & flexible – Woody – stiff, have cork layer, usually brown

30. Leaves [119] Cuticle = protection Stomata = gas exchange, water loss (transpiration) Epidermis = protection, color Mesophyll – Palisade = most PHOTOSYNTHESIS – Spongy = Vascular bundles run through it

31. Flowers [131] Pistils = female reproductive structures Stamens = male reproductive structures Complete flowers – Have petals & sepals – Have male and female parts Incomplete flowers = missing one or more parts

33. Types of Angiosperms [115] Monocots mono = “one” cot = “seed leaf” Approx. 60,000 species Flowers = multiples of 3 Leaf veins parallel Dicots di = “two” cot = “seed leaf” Approx. 170,000 species Flowers = multiples of 4 or 5 Leaf veins branching

34. Plant Tropisms Tropism = plant response to external stimulus – Positive: plant moves toward stimulus – Negative: plant moves away from stimulus Types: – Phototropism = light – Gravitropism = gravity – Thigmotropism = touch (nastic movement – direction does not matter)

35. Plant Hormones Hormone – chemical produced in one part of an organism that has an effect on a different part of the organism Types – Auxins – regulate growth – Gibberellins – speeds growth, germination – Abscisic acid – dormancy, close stomata, stress – Ethylene – ripens fruit