Introduction to Plants

1. Essential Questions: Why are plants important to life on Earth? How have they adapted to life on land? How have plans evolved to respond to their environment? Introduction to Plants

2. What do Plants Need to Survive? Label your picture in Notes: • Sunlight to make Glucose • Water (and Minerals) • Carbon Dioxide to make Glucose! Why do we need Plants? • Source of Sugar (energy) for the base of the energy pyramid! • Major source of Oxygen!

3. Where did Plants come from? • Plants likely evolved from plant-like Protistgreen algae from a watery environment. • Oparin: Life came from the oceans. • Likely evolved around 500-400 million years ago!

4. Plant General Characteristics • Carry out photosynthesis (autotrophs) • Produce cellulose in their cell walls • Non-motile (don’t move around) • Reproduce sexually and asexually • Have specialized tissues and organs

5. Plant Diversity Bryophytesnon-vascularland plants Pteridophytesseedless vascular plants Gymnospermpollen & “naked” seeds Angiospermflowers & fruit conifers flowering plants mosses ferns seed plants vascular plants colonization of land

6. Bryophytes – Non Vascular Plants • Includes: mosses, liverworts, hornworts • First land plants; had to overcome obstacles • avoid drying out (desiccation) – live in moist areas • develop a means of support (roots and stems) • develop new reproductive methods • obtaining nutrition • No vascular tissue, so they are close to the ground to draw up water by osmosis! Their reproduction also relies on the use of water!

7. Bryophytes: mosses & liverworts

8. Tracheophytes – vascular plants Pteridophyta - ferns Have vascular system (can grow taller than mosses and do not have to directly live in water) Seedless – produce by spores (still rely on water and wind for reproduction)

9. Pteridophytes: Ferns Selaginella Psilotum Horsetails Ferns

10. Tracheophytes – Vascular plants • Gymnosperms – means “naked seed”, not protected by fruit. Can reproduce through wind or other methods on land via seeds! • Class Ginkoopsida– Gingkos; one species exists today, living fossil • Class Cycadopsida– Cycads; found in tropics • Class Pinopsida– cone bearers; 9 families contain over 300 species, evergreens: pines, spruce, hemlocks, firs What does Vascular Tissue mean? Means they have xylem (water) and phloem (sugar) to transport water up from the ground into the rest of the plant! Can grow very tall unlike mosses and ferns!

11. Gymnosperm: conifers

12. BRISTLECONE PINE TREE Earth's oldest living inhabitant "Methuselah" at 4,767 years, has lived more than a millennium longer than any other tree.

13. Tracheophytes – vascular plants Angiosperms – flowering plants, produce a form of fruit! (A wall of tissue surrounding a seed.) “hidden seed.” Gives animals a tasty treat to place their offspring elsewhere. Can reproduce on land. • Two classes of angiosperms are based upon the number of Cotyledon: tiny seed leaves that store or absorb food for developing embryo. • Class Monocotyledonae– Monocots (1) • Class Dicotyledonae– Dicots (2) • Have Unique life spans. • Those who die in one season are called annuals. • Those who die in two years are called biannuals. • Those who live many years are called perennials.

14. Angiosperm: flowering plants

15. Types of Angiosperms:Monocots versus Dicots

16. Plant Structure: Roots • Rootsanchor plants into the ground, absorb water & minerals from the soil, protect the plant from bad bacteria/fungi, and transport these materials to the stem. • Contain xylem and phloem in the center of the root. • Root pressure – dew is an example of root (pressure forcing excess water out of the plant) • The root cap burrows through the soil and the cells are replenished by the apical meristem. • Meristem = areas of rapidly dividing cells

17. Plant Structure: Stems • Stems can be either woody or herbaceous. • Transpiration – as water evaporates, the energy released pulls water up the stem • Vascular tissues are arranged differently in stems than leaves. • Monocots: scattered in stem • Dicots: circular pattern in stem • Xylem – transports water & minerals • Phloem – transports sugars & hormones • Portion of a plant that stores sugar is called a sink.

18. Plant Structure: Leaves • Permit exchange of CO2, O2, and H2O with the environment • Site of photosynthesis (SUN!) • Leaves are protected by a waxy cuticle. • Petiole – vascular tissues extending from stem to leaf (appear as veins) • Mesophyll – contain chlorophyll • Guard cells & Stomata – regulate water loss through the underside of the leaf (Transpiration) • Monocots: parallel veins • Dicots: net veined

21. Why are Roots, Stems & Leaves important? Root pressure – dew is an example of root pressure (forcing excess water out of the plant)‏ Transpiration – as water evaporates, the energy released pulls water up the stem Capillary pressure – water uses cohesion (unlike particles stick together) and adhesion (like particles stick together) to push its way up xylem in plants; limiting factor in height of trees.

22. Plant Responses: Tropisms • Plants respond to their environment as other organisms do. • Photoperiodism affects the timing of flower production. • Duration of light and dark periods in the day • Short-day plants, Long-day plants, day-neutral plants • Tropism – a plant’s response to an external stimulus that comes from a particular direction. • Involve growth, so they are notreversible. • Phototropism (Light) • Gravitropism (Gravity) • Thigmotropism (Touch) • Nastic movement –Do not involve growth, so are reversible. • Example: folding of a venus flytrap.

23. Plant Responses: Hormones • Hormones cause a physiological change either in growth or development. • Auxins (IAA) – stem elongation. • Gibberellins – increase rate of seed germination and allows the stem to grow taller. • Cytokinins – stimulate proteins for cell division and extends the life of the plant. • Ethylene – ripens fruits and the emergence of seeds from the soil. • Abscisic Acid – helps leaves prevent water loss by hardening certain leaf cells.

24. Final Note: Specialized Tissues Meristematic tissue – only tissue that produces new cells by mitosis, found on edges Parenchyma – used for storage, surrounded by vascular tissue Vascular tissue – like arteries and veins! Xylem – transports materials up from the roots to leaves and supports the plants as “wood” after the cell dies Phloem – transports materials down from the leaves to roots and stem Vascular Cambium – makes more vascular tissue Cork Cambium – outer bark of trees