Classification of Plants

Transcription

1 Classification of Plants

2 Plants Aquatic Plants Ex. green algae Similarities between green algae and land plants: A) have chlorophylls a and b B) cellulose cell walls C) store food energy in the form of starch (rather than glycogen)

3 Plants to Land (400MYA) Adaptations that needed to be evolved before plants could live on land: A) protection from drying out B) system of transport from outside environment to cells in the body of plant C) system to support the body of plant

4 Adaptation to Land 3 organs that developed to adapt to life on land: A) roots: penetrate soil to anchor plant; reach water source B) leaves: greater surface area for photosynthesis C) stems: rigid tissue to raise and support leaves

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6 Land plants: non-vascular vs. vascular Vascular plants appeared 360MYA A vascular tissue : a system of tubes that carry water and dissolved nutrients through a plant

7 non-vascular Land plants: vs. vascular Non-vascular (bryophytes) No vascular (transport) tissue Have root-like, stem-like and leaf-like structures (poorly developed roots, leaves and stems) Grow short, small ex. mosses, liverworts, hornworts Vascular (tracheophytes) has vascular tissue to transport water and nutrients Have true roots, stems and leaves Grow taller, larger 1) seedless (spore producing) Ex. ferns 2) seed producing Ex. conifers, flowering plants

8 Non-Vascular vs. Vascular Advantage of vascular plants? - can live in drier environment - can grow larger (water and nutrients can reach far with the vascular tissue) Non-vascular plants live in moist environment and have smaller sizes.

9 Non-vascular (bryophytes) Mosses Liverworts Hornworts

10 Vascular (tracheophytes) 1) Seedless (spore-producing) ex. ferns

11 Grow in marshes and edges of shores; requires water for reproduction spores (sperm) swim in water to the female organ (in different plant or same plant)

12 Advantages of having seeds A) food storage B) tough waterproof coat protection against harsh conditions C) remain dormant- survive exposure to harsh conditions D) sexual reproduction without needing water

13 Gymnosperm- naked seed ex. ginkgoes, conifers

14 Angiosperms-flowering plants

15 Examples Gymnosperms vs. Angiosperms Conifers: produce cones in the spring and summer Male vs. female cones Flowering plants Also grass and herbs (in clusters) (scattered, hidden seeds)

16 Seed Structure Gymnosperms vs. Angiosperms Means naked seed Seeds that are exposed to the environment (often as cones) Thin cover of protection Means seed in a vessel Seed = embryo +nutrient storage+ coat Seeds that are not exposed to the environment (drought, fire ) Seed protected with body of fruit

17 Preferred Environment Gymnosperms vs. Angiosperms Environments with long, cold winters and low amounts of nutrients in the soil Found in Canada and northern Europe and northern Asia Found all over the world

18 Number of species Gymnosperms vs. Angiosperms Smaller in number Approx species Larger in number Approx species

19 . 2 groups Flowering Plants (Angiosperms) Monocotyledons Dicotyledons. roots, stems, leaves. vascular tissues (transport). flowers, fruits (contain seeds)

20 Two peanut seeds Two apple seeds in the hard ovary vs in the fleshy fruit

21 Monocotyledons and Dicotyledons Cotyledon: the structure in a plant s seed that stores carbohydrates for the seedling It s known as seed leaf because the plant s first leaf develops from it. ex) onion- single leaf monocot alfalfa- two leaves dicot

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23 Monocotyledons Parallel veins

24 Dicotyledons Veins in network

25 Structure Monocots Dicots Number of cotyledons Number of flower petals Number of species Examples 1 2 Multiples of 3 Multiples of 4 or 5 Fewer Tulip, lily, corn, onion, grass, rice, banana More Rose, maple tree, carrot, potatoes, beans

26 Root structure

27 Structure Monocots Dicots Root crosssection Vascular bundles are arranged in a ring Root system Fibrous rootsmany thin roots xylem in the center of the root (with an X shape) and phloem outside the xylem. Tap roots one large vertical root with smaller branches Stem crosssection Tissue Vascular bundles are scattered Herbaceous soft & flesh stems Only about 10% are woody Vascular bundles are arranged in a ring Woody- tough, rigid

28 Monocot Stem vs. Dicot Stem vascular bundles- scattered vs. in a ring

29 Leaf Structure Monocots Dicots Leaf crosssection Leaf structure Spongy mesophyll Long strips Parallel veins Palisade mesophyll + spongy mesophyll Broad leaf Net-like veins

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32 Double fertilization 1) between a sperm(1n) and the egg (1n) becomes the zygote (2n) develops into an embryo 2) between a sperm(1n) and the two polar nuclei (n +n) becomes the endosperm (3n) provides nutrients for the embryo each ovule forms a seed (there are many ovules in the ovary) the ovary develops into a fruit

33 Gametes Inside the anther, microspores are produced through meiosis. These microspores give rise to the pollen grain (1n). The female reproductive organ, the ovary, contains developing ovules. Each ovule produces megaspores (haploid) through meiosis. One megaspore survives in each ovule and develops into an egg (1n). When pollen reaches the stigma, it grows a pollen tube to extend down the style.