Plant General Characteristics

1. 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 Botany: the study of plants

2. Where did Plants come from? • Plants likely evolved from plant-like Protist green algae from a watery environment. • Likely evolved around 500-400 million years ago!

3. What do Plants Need to Survive? • Sunlight • Water and Minerals • Gas Exchange • Movement of Water and Nutrients

4. Kingdom Plantae adaptations:Specialized Tissues • 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 • Parenchyma – used for storage, surrounded by vascular tissue • Meristematic tissue – only tissue that produces new cells by mitosis, found on edges • Cork Cambium – outer bark of trees

5. 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!

6. Tracheophytes – Vascular plants • Gymnosperms – means “naked seed”, not protected by fruit. Can reproduce through wind or other methods on land! • 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 Vasuclar Tissue mean? Means they have xylem (water) and phloem (sugar) to transport water up from the ground into the rest of the plant!

7. Tracheophytes – vascular plants Angiosperms – flowering plants, produce a form of fruit! (A wall of tissue surrounding a 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.

9. 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

10. 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.

11. Plant Structure: Leaves • 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

12. Plant Asexual Reproduction • Vegetative Reproduction – when plants form new plants from portions of their own roots, stems, or leaves • Spores – non-seed vascular plants (ferns) release spores

13. Plant Sexual Reproduction Overview • Pollination – when pollen is deposited on stigma. • Fertilization – when pollen grain reached the ovary and fuses with the egg. • After fertilization, the seed develops food storage regions for the embryo called fruit. • Seeds are eventually dispersed using many different methods. (Wind, Animals, Water, Fruit, etc) • Remember, this is called the Alternation of Generations! • Can remain dormant until temperature and moisture cause the seed to start early growth called germination. • The systematic cultivation of plants by humans is called agriculture.

14. How Plants Reproduce: Flowers & Flowering • Flowers are made up of four organs: (called Perfect Flower) • Petals – colorful leaf like structure around the stem. • They attract insects and other pollinators of the flower. • Sepals – green leaf like structure around the flower stem beneath the petals. • They enclose the bud before it opens and protect the flower while it is developing. • Stamens – male part of the flower where at their tip is the anther that rests on the filament contains pollen. • Carpel– Female part of the flower, which contains sticky stigma where pollen grains land and travel down the style to the ovary and ovules.

15. Fertilization: Seed & Fruit Production • 2 sperm fertilize the female, one the egg (1n), the other the central cell (2n) • The walls of the ovule become the protective seed coat, the central cell becomes the endosperm or food for the embryo, and the ovary wall the fruit. • Because two fertilization events take place at the same time, it is called double fertilization. • Fruits and seeds are modified for dispersal. • Shape of seed can determine type of dispersal (wind, water, animal, etc) • Seeds can stay dormant for long periods of time!

16. 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.

17. 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.