Plants

1. Plants

2. What are Plants? • Multicellular eukaryotes • Have cell walls made of cellulose • Develop from multicellularembyros • Carry out photosynthesis

3. Evolution of Plants • Started in water • Evolved from an organism similar to multi-cellular algae living today Cone-bearing plants Ferns Flowering plants Mosses Flowers; seeds enclosed in fruit Seeds Vascular Tissue Green algae ancestor

4. Nonvascular Plants • Called bryophytes • Depend on water to reproduce • Lack vascular tissue (draw up water by osmosis) • Mosses, liverworts, and hornworts

5. Vascular Plants • Have vascular tissue (tissues that conduct water and nutrients throughout the plant) • Xylem: transports water • Phloem: transports sugar

7. Vascular Plants - Tracheophytes • Ferns • Seedless plants ~ Reproduce with spores; Need water for reproduction. • Have roots, stems, and leaves

8. Gymnosperms • Vascular • Seed bearing plant • Conifers ~ Seeds are in cones.

9. Angiosperms • The flowering plants. • Vascular • Bear seeds in fruits.

11. Reproductive shoot (flower) Terminal bud Node Internode Terminal bud Shoot system Vegetative shoot Blade Petiole Leaf Axillary bud Stem Taproot Root system Lateral roots Figure 35.2 Vascular Plants • 3 basic organs: • Roots • Stems • Leaves

12. Root • Organ that anchors the vascular plant • Absorbs minerals and water • Often stores organic nutrients

13. Root Anatomy(cross-section)

14. Stem • Organ that consists of an alternating system of nodes, the points at which leaves are attached

15. Stem

16. Leaves • Is the main photosynthetic organ of most vascular plants • Leaves generally consist of: • A flattened blade and a stalk • The petiole, which joins the leaf to a node of the stem

17. Leaf Anatomy • Cuticle – Waxy layer that protects leaf. • Epidermis – Outermost layer of cells. Upper and lower. • Palisade mesophyll ~ Hot dog shaped cells lined up like Popsicle sticks under the epidermis. Have lots of chloroplasts, and carry out most of the photosynthesis. • Spongy mesophyll ~ Rounded, loosely arranged cells under the palisade mesophyll. Spaces between the cells allow oxygen and CO2 to circulate.

18. Leaf Anatomy • Vein ~ A bundle of phloem and xylem surrounded by protective cells. This vascular tissue carries water to and from the leaf for photosynthesis VEIN

19. Gas Exchange in Leaves • Stomata – Holes in lower epidermis that allow CO2 to enter and O2 to leave. • Guard cells – Pickle-shaped cells on each side of stoma that open and close the hole.

21. Plant cross-section

22. Turgor Pressure – Plant vocabulary • Turgor Pressure – The pressure of water against the inside of plant cell walls. • Turgor pressure maintains a plants shape and stiffness. As water is lost, turgor pressure decreases the plant wilts.

23. Nonvascular Plant Reproduction Mosses produce sperm that must swim to meet the egg. Once egg and sperm meet, a spore is produced. Spores do not have a coat to protect them like seeds do, so they need moisture!

24. Gymnosperms • Gymnosperms – “Naked seeds” • Produce seeds in cones • Leaves are needle-like • Evergreens – don’t shed leaves seasonally. • Pines, cedar

25. Gymnosperm Reproduction • The diploid sporophyte generation (pine tree) produces male and female cones (gametophytes) • The male cone produces pollen • The female cone holds the eggs • Pollen travels by the wind to the female cone • The pollen and the egg meet and form a seed • The seed grows into the sporophyte generation (pine cone)

26. Angiosperms • Angiosperms - “covered seeds” • Flowering plants • Produce seeds in fruits. • Leaves are broad • Deciduous – Lose and replace leaves seasonally.

27. Flowers • Flowers are the main reproductive organ of the plant. • Flowers produce egg and sperm cells • Some flowers are hermaphroditic • Parts of the flower eventually become seeds and fruits.

28. Flower Anatomy

29. Flower Anatomy • Pistil- Female • Stigma: sticky portion where pollen grains land • Style: stalk; pollen tube forms inside the style • Ovary: contains ovules • Ovules: produces female gametophytes

30. Flower Anatomy • Stamen - Male • Anther: produces pollen grains (male gametophytes) • Filament: supports anther

31. Flower Anatomy

32. Angiosperm Reproduction • The plant produces flowers • Flowers contain both male and female structures • The male part of the flower releases pollen • The pollen is carried by a pollinator to the female part of the flower • The pollen lands on the female part and grows a pollen tube • The pollen meets the egg and fertilization takes place • The egg and sperm make a seed • The ovary of the flower becomes a fruit to protect the seed until it is planted

33. Pollination • Process by which pollen is transferred to plants • Wind pollination: pollen is transferred via wind • Animal pollination: pollen is transferred via animals

34. Seeds and Seed Dispersal • Purpose is to protect and provide nutrition for a developing plant embryo • Seeds are dispersed by: • Animals (contained in fleshy, nutritious fruits; pass through animals digestive system) • Wind and water (seeds are generally lightweight)

35. Fruit • As angiosperm seeds mature, the ovary walls thicken to form a fruit that encloses the developing seed