Plant Reproduction and Behavior

1. Plant Reproduction and Behavior By : Catherine Dale and Jackie Lomboy

2. Plant Diversity • Bryophytes • Non-vascular land plants • Pteridophytes • Seedless vascular plants • Gymnosperms • Pollen & “naked” seeds • Angiosperms • Flowers and fruit

3. Examples • Bryophytes • Mosses and liverworts • Pteridophytes • Ferns, selaginella, Psilotum, Horsetails, fiddleheads, and fronds • Gymnosperms • Ginko, cyads, and conifers • Angiosperms • Fruiting and flowering plants

4. Bryophytes (First Land Plants) • Non-vascular • No true root system • No system for the transportation of water • Spores • used for reproduction in replacement for seeds and flowers • “swimming” sperm (flagellated sperm) • Life cycle is dependent upon the haploid gametophyte stage • The only land plants whose history includes a dominant haploid gametophyte stage • Produce Gametes • Gametes fuse to form zygote • Zygote develops into an embryo

5. Pteridophytes • Vascular plants • First vascular plants • Contain xylem, phloem, roots and leaves for nutrient/water transport. • “swimming” sperm (flagellated sperm) • Spores • Use spores to reproduce instead of flowers or seeds • Haploid cells sprout and later become gametophyte • Sporophyte-oriented • Natural plant is the diploid sporophyte, with the only haploid structure being the gametophyte in season

6. Gymnosperms (conifers) • Vascular plants • First vascular plants • Contain xylem, phloem, roots and leaves for nutrient/water transport. • Heterospory • male and female spores • Seeds • First seed plants • Use cones • Naked seeds. NO FRUIT! • Pollen • contains male gametophyte • Eliminates the requirement for water for fertilization

7. Angiosperms • Vascular plants • First vascular plants • Contain xylem, phloem, roots and leaves for nutrient/water transport. • Heterospory • male and female spores • Flower • First flowering plants • Aid for sexual reproduction • Seeds protected by fruit • Pollen • contains male gametophyte • Eliminates the requirement for water for fertilization

8. Flowering plants Dicots Monocots • 2 cotyledons • Woody plants, trees, beans, or shrubs • Network of veins within the leaves • 1 cotyledon • Grasses, lillies, and palms • Parallel Veins within leaves Double Fertilization: (only occurs in Angiosperms) the process that involves the joining of a female gametophyte with two male gametes.

9. Flower • Anther: Pollen-bearing part of the stamen • Stigma: takes in pollen • Style: stalk structure in female flower parts • Ovary: protects the ovule and after fertilization, becomes the fruit • Ovule: female reproductive cells • Stamen: male reproductive organ • Sepal: modified leaf • Pollen Grains: transports male gamete to female part of the flower Self pollination: transfer of pollen from an anther to a stigma of the same flower

10. Fruits • Product of a ripened ovary after fertilization. • Endosperm: tissue produced in the seed • Seed coat: The outer protective covering of a seed

11. Photoperiodism • ability of plants to measure the length of periods of light • Short Day plants: a plant that flowers only after being exposed to light periods shorter than a certain critical length, like early spring or fall (ex. Coffee, Strawberries). • Long day plants: plants that require a long period or exposure to light each day in order to produce flowers (ex. Clovers, Turnips).

12. Transpiration • Transpiration: The evaporation of water from plants, usually the leaves. • Adaptations to prevent transpiration: fewer stomata, small leaves, leafless plants, light-colored leaves, thicker cuticles, thick fleshy leaves, and waxy cuticles

13. Transpiration Video

14. Water transportation • Xylem: supporting and water-conducting tissue of vascular plants that transports water and nutrients from the roots to the rest of the plant. • Phloem: Living tissue that transports organic nutrients.

15. Auxin • Darwin concluded that a plant hormone made in tip of plants somehow moves down and induces other cells to extend. Later, this hormone became known as Auxin. • Auxin and Apical Dominance: Auxin, when locoated in the more dominant growing tip of a plant, slows down the growth laterally. This is the reasoning behind the triangular shape of conifers.

16. Auxin (continued) • Auxin in Gravitropism: When a new seed begins to form roots, Auxin forms on the lower side of the root. As the concentration of Auxin rises, the lower cells are prevented from expanding while the cells above continue to grow. This causes the roots to bend down at a slight angle. • Auxin in Elongation: causes newly divided cells to pump H+ into their cell walls, raising the pH and therefore activating specific enzymes.

17. Other Hormones • Gibberellin: acts as a hormone to stimulate the synthesis of enzymes during germination of seedlings. This has occurs in order for it release the stored nutrients. • Cytokinin: stimulates cell division in plants. Usually works along with Auxin. Cytokinin speeds up the development of a shoot. • Ethylene: controls the ripening process of fruits, protects new leaves from the roughness of growing up through the soil, and insures that a flower is female. • Abscisic Acid: stimulates winter dormancy by restraining mRNA production, and enters guard cells to prevent water loss.

18. Growth Responses • Phototropism: the directional growth of a plant/fungus that occurs in response to a light source. This is a result of the unequal concentration on Auxin on either side of a plant. • Gravitropism: growth movement of a plant/fungus as a result to gravity and the concentration of auxin. Roots have positive gravitopism; stems, negative. • Thigmotropism: growing pattern when a plant grows due to the touch of a stimuli. Vines are an example because they develop tendrils that coil aorund certain surfaces. The unequal concentrations of Auxin is what causes the plant to bend around the stimuli.