Understanding Plant Structure and Reproductive Processes: Leaves, Flowers, and Growth Mechanisms

1. LEAVES23.4

2. Function • Photosynthesis • Transpiration – pulling water up from the roots and out the leaves

3. Structure • Epidermis • Upper – covered by cuticle • Lower – contains stoma with guard cells

4. Cont. • Palisade layer – many chloroplasts • Mesophyll – many air spaces • Vascular bundle – “veins”

5. Vein Epidermis with cuticle Pallisade Layer Mesophyll Stomata

8. External Structures • Petiole – structure that attached leaf to stem • Blade – thin, flat area of leaf; different sizes, shapes & arrangement • Mid rib – main vein • Leaf margin – edge of leaf

9. Venation in Monocots and Dicots • Monocots – parallel leaf venation • Dicots – netted venation

11. Pop Quiz

12. Flowers, Fruits & SeedsCh. 24

13. Angiosperms reproduce using flowers.

14. Flowering Plants have: Dicot Monocot 3 3 4 2 5 4 2 1 5 6 1 8 6 7 Multiples of 3 Multiples of 4 or 5 Flowers 6

15. Flowers • Composed of modified leaves • Sepals – usually green; enclose bud • Petals– brightly colored; just inside sepals • Stamen – male reproductive organ • Filament - stalk • Anther – produces pollen (male gamete) • Carpel (pistil) – female reproductive organ • Stigma- sticky; pollen attaches here • Style – narrow stalk • Ovary – contains ovules

17. Stamen Anther Filament male part of flower Parts of a Typical Flower

18. Stigma Pistil Style Female part of flower (Sounds like “Pigtail”) Ovary Parts of a Typical Flower

19. Plant Reproduction Plants can reproduce asexually by vegetative propagation. Stems Roots Plantlets Stems, plantlets and roots can become a new plant.

20. Plant Reproduction Plants can reproduce asexually by plant propagation. Cuttings Grafting & Budding A “cut” from a plant can grow roots when put in soil. Two plants are attached to form one plant.

21. Angiosperm Life Cycle • Pollination – transfer of pollen from anther to stigma of carpel • Often dependent on pollinators • Pollen grows a tube through which sperm nuclei travel • Fertilization – • sperm nuclei fuse with ovule inside • produce a seed • Ovary ripens into a fruit

22. Fruits – ripened ovary; type determined by structure of ovary and ovules • Dry • Nuts • Fleshy • Drupes - apple • Pomes - peach • Berries • Hesperidium - orange • Pepo - cucumber • Aggregate - raspberry

24. Seed Dispersal • Animal • Wind • Water

25. Seed Germination • Timing controlled by climate (moisture, temperature, etc.) • Endosperm (food source) swells with moisture and cracks open seed coat • Root emerges first • Cotyledons emerge second • Monocot – one seed leaf • Dicot – two seed leaves

26. Plant Growth • Controlled by hormones (auxins) • Cause “tropisms” • Gravitropism • Thigmotropism • phototropism