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Introduction to Plants Mrs. M. Rightler. Earliest Plants Algae Phytoplankton Lived in the sea.

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Presentation on theme: "Introduction to Plants Mrs. M. Rightler. Earliest Plants Algae Phytoplankton Lived in the sea."— Presentation transcript:

1 Introduction to Plants Mrs. M. Rightler

2 Earliest Plants Algae Phytoplankton Lived in the sea

3 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

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 (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

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 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

27 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)

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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