Plant Structure, Reproduction, and Development

1. Plant Structure, Reproduction, and Development

2. Angiosperms • Cotyledons – embryonic leaves • Monocot – one embryonic leaf • Dicot – two embryonic leaves • Differences between Monocots & Dicots • Veins are parallel /branched • Vascular bundles complex /ring • Leaves arranged in multiples of 3 /multiples of 4 or 5 • Fibrous roots /taproot

3. SEED LEAVES LEAF VEINS STEMS FLOWERS ROOTS MONOCOTS Onecotyledon Main veins usually parallel Vascular bundles incomplex arrangement Floral parts usuallyin multiples of three Fibrousroot system DICOTS Twocotyledons Main veins usually branched Vascular bundles arranged in ring Floral parts usually in multiples of four or five Taprootusually present Figure 31.2

4. Angiosperms • Most angiosperms are dicots • This group includes shrubs, trees (except conifers), and many of our food crops • Monocots include orchids, bamboos, palms, lilies, and grains and grasses.

5. Plant Body • Root system – anchors the plant into the soil • Roots have root hairs – outgrowth of epidermal cells • Shoot system – part of plant above ground stems – support leaves and grounded nodes– points where leaved are attached leaves – main site of photosynthesis terminal bud – node at tip of plant; responsible for growth lengthwise; apical dominance (inhibits growth of axillary buds) axillary buds – located in angles formed by the leaf; usually dormant; causes the plant to become bushy

6. Terminal bud Blade Leaf Flower Petiole Axillary bud Stem SHOOTSYSTEM Node Internode Taproot Roothairs ROOTSYSTEM Figure 31.3

7. Modified Roots and Shoots STRAWBERRYPLANT • Modified taproots – sweet potatoes, sugar beets, & carrots/ stores starch • Uses this stored sugar source for active growth and producing flowers and fruit • Modified Stems • runner – horizontal stem • rhizomes – horizontal stem underground • tubers – white potatoes that are at the end of rhizomes that store sugar Runner POTATOPLANT Rhizome IRISPLANT Rhizome Tuber Taproot Root

8. Modified Roots and Shoots • Modified leaves • Grasses have no petioles • Celery have enormous petioles that we eat • Tendrils have coiled tips which aid in climbing • Cactus have spines

9. Plant Tissue Systems • Epidermis • Covers and protects • First line of defense • Cuticle is the waxy substance that helps plants to retain water • Vascular System • xylem/phloem – transports water and nutrients • support

10. Plant Tissue System • Ground Tissue System • Filling spaces, bulk • Parenchyma, collenchyma, sclerenchyma • Photosynthesis, storage, support

11. Plant Tissue System • Roots • Epidermis • Covers roots • Entrance for water and nutrients • May form root hairs • No cuticle • Ground tissue • Cortex – parenchyma, store food • Endodermis – selective barrier, thin layer of cells decides what passes between vascular tissue and cortex • Vascular Bundles • xylem – spokes of wheel • phloem – fills in wedges between spokes

12. Xylem VASCULARTISSUESYSTEM Phloem Epidermis Cortex GROUNDTISSUESYSTEM Endodermis Figure 31.6B

13. Plant Tissue System • Leaf • Epidermis • Covered by cuticle • Small pores called stomata • Surrounded by guard cells • Ground Tissue • Mesophyll composed of parenchyma cells and chloroplast • Air located in spaces between cells • Vascular System • Vein – composed of xylem and phloem surrounded by parenchyma cells

14. Figure 31.6D

15. Plant Tissue System • Stem • Epidermis • Thin layer of cells • Covered by cuticle • Ground Tissue • Dicot - 2 parts / Monocot – 1 part (ground tissue) • Pith – food storage • Cortex – fills spaces • Vascular Tissue • Occurs in vascular bundles • Dicot – ring • Monocot - random

16. Figure 31.6C

17. Plant Cells • Three main differences between animal cells and plants cells are • Cell wall • Central vacuole • chloroplasts Figure 31.5A

18. Plant Cells Five Major Types of Plant Cells 1.Parenchyma cells – most abundant type • Remain alive at maturity • Primary cell wall (thin) • Function in food storage and photosynthesis • Multisided 2.Collenchyma cells primary cell wall (thick) alive at maturity provide support in plants that are still growing

19. Parenchyma Cells Primarywall(thin) Pit Figure 31.5B

20. Plant Cells 3. Sclerenchyma cells • Rigid secondary walls • Hardened with lignin • Found in regions that is not growing • Dead at maturity • Two types of sclerenchyma cells • Fiber – long and slender and occurs in bundles; hemp fibers make rope • Sclereid – stone cell; short, irregular shaped secondary wall; found in nutshells and sead-coats

21. Sclerenchyma Cells Pits Secondarywall Fibercells Primarywall FIBER Figure 31.5D

22. Sclerenchyma Cells Sclereids (stone cells) Secondarywall Sclereidcells Primarywall Pits SCLEREID Figure 31.5D continued

23. Plant Cells 4. Water-Conducting cells • Rigid, lignin-containing secondary cell walls • Cells are dead at maturity • Hollow in the middle • Functions in support Two types of water-conducting cells 1. Tracheids – long cells with tapered ends 2. Vessel Elements – wide, short cells Pits Tracheids Vessel element Pits Openingsin end wall

24. Plant Cells 5. Food – Conducting cells (sieve tube members) -arranged end to end - thin primary walls with no secondary wall -alive at maturity -transports sugars and minerals -sieve plates – located at the ends of the sieve tube members

25. Sieve plate Companioncell Cytoplasm Primarywall Sieve Tube Members

26. Primary Growth • Indeterminate growth – continue to grow as long as they live • Annuals – wheat, corn, rice • Biennials – beets, carrots • Perennials – trees, shrubs, grasses

27. Primary Growth • Apical meristem – lengthwise growth • Root cap – protects apical meristem in roots • Two functions of root apical meristem • Replaces cells of root cap • Produces cells for primary growth

28. Primary Growth • Three regions of roots • Epidermis (outermost) • Cortex (bulk) • Vascular tissue • Elongation • uptake of water • cellulose fibers extend (accordion) • forces roots into soil • Differentiation – caused by master gene; causes unspecialized cells to specialize

29. Vascularcylinder Cortex Epidermis DIFFERENTIATION Root hair ELONGATION Cellulosefibers CELLDIVISION Apical meristemregion Rootcap Figure 31.7B

30. Primary Growth • Three Zones • Cell division • Elongation • Differentiation

31. Flower Reproduction • The angiosperm flower is a reproductive shoot consisting of • sepals • petals • stamen • carpels Anther Carpel Stigma Ovary Stamen Ovule Sepal Petal Figure 31.9A

32. Fertilization of an Angiosperm • Formation of a pollen grain • Cells that make pollen grains are located in the anther • Meiosis- four haploid spores that eventually form two haploid cells called a tube cell and a generative cell • Wall forms around the two cells known as a pollen grain • Animals, wind, and water transport pollen grain (male gametophyte)

33. Fertilization of an Angiosperm • Formation of an Egg Cell • Megaspore mother cell – forms 4 haploid megaspores and three degenerate • Surviving megaspore enlarges/ mitotic division • End Result – One large cell with two haploid nuclei and six smaller cells. • One of the six smaller cells is the haploid egg.

35. Pollination Sugar/enzymes on stigma causes tube cell to grow and form pollen tube • Both cells (generative cell and tube cell) travel to embryo sac • Generative cell forms two sperm cells • One sperm cell fertilizes the nucleus with the polar nuclei (triploid nucleus/3n)

36. Pollination • One sperm cell fertilizes egg cell (diploid nucleus/2n) • Triploid forms endosperm/functions to nourish embryo (popcorn) • Flowering plants (double fertilization) • Alternation of generations • Haploid – female gametophytes (ovules/egg), male gametophytes (generative cell/sperm) • Diploid – sporophyte (plant/flower); produces haploid spores by meiosis