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Introduction to Plants

Introduction to Plants. Mrs. M. Rightler. Earliest Plants. Algae Phytoplankton Lived in the sea. Problem Drying Out Making Food Reproduction Gravity & Support Getting water & nutrients. Solution Waxy cuticle, stomata Formed leaves Develops spores & seeds Bark (cork) & vessels

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Introduction to Plants

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  1. Introduction to Plants Mrs. M. Rightler

  2. Earliest Plants • Algae • Phytoplankton • Lived in the sea

  3. 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 Problems with life on land

  4. Types of Plants • Avascular • Bryophytes • nonseed plants • Tracheophytes • vessels for transport and support

  5. Mosses & Liverworts: The Bryophytes • First land plants • AVASCULAR = very small • 500 m.y.a. • Must grow in moist environments • Used for fuel (peat)

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

  7. 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

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

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

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

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

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

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

  14. 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

  15. 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

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

  17. Minor Gymnosperm Groups • Cycadophyta (1st 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

  18. 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

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

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

  21. Overall Structures [121] • Roots • Stems • Leaves • Flowers

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

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

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

  25. 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

  26. 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 Types of Angiosperms [115]

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

  28. 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

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