Reproduction of Plants Propagation

Sexual and Asexual Asexual Sexual No seeds Leaf, stem, or root Union of pollen and egg Pollination Fertilization Pollen tube, male gametes unite with egg cell to form zygote

Pollination Transfer of pollen Pollen grains Self – pollination Pores where pollen tubes grow Self – pollination Cross – pollination Wind or animal

Gymnosperms “Naked seeds” Conifers or Cone – bearers Pollen cones or seed cones Seed cones are larger Pollination occurs in late spring Seed cones stand up on tips of branches and open slightly Ovule produces sticky liquid that pollen gets trapped in Pollination complete seed cone turns upside down

Angiosperm Flowering plants Annual or perennials Ovules develop in ovary Fertilization Pollen lands on stigma Pollen tube to enter style Enters ovary and sperm is released in ovule

Parts of the Seed Hypocotyl Radicle Epicotyl Cotyledons (seed leaves) Connection b/w cotyledon and radicle Radicle Hypocotyl and embryonic root Epicotyl Shoot – stems and leaves Cotyledons (seed leaves) Endosperm Stores plant food Seed coat Outer covering protects embryo

Seed Dispersal Ovules develop inside of an ovary Fleshy part nutritious for animals Hooks, spines, or parachutes Large number of seeds

Seed Germination Time between seed is planted, its development until it is self – supporting Begin once planted or lay dormant Physical or chemical reactions Nutrients inside seed

During Germination Embryo swells to burst through the seed coat Radicle (10 root) Grows downward Hypocotyl connected to cotyledons and radicle Arches and pushes up through soil Arch emerges the hypocotyl straightens Cotyledons and epicotyl are pulled out of the soil

Primary leaves unfold and stem elongates Primary leaves/true leaves completely emerge Cotyledons fall off Photosynthesis begins

Improving Chances of Germination Seeds are primed or enhanced Stimulate growth hormones in various solutions Loam, pH, nutrients, and drainage Scarification Soaking seeds prior to planting

Plant Growth Regulated by hormones Stimulate or restrict growth Auxins, gibberellins, cytokinins, inhibitors

Plant Hormones Auxins Gibberellins Cytokinins Accelerates the growth in stem and leaf Gibberellins Stimulate growth in stem and leaf Cytokinins Stimulates cell division works with auxins Inhibitors prevent germination or stem growth Stimulate fruit ripening by emitting ethylene gas

Other factors Apical dominance Terminal bud secretes hormones Inhibit lateral buds on same shoot Once plant reaches flowering stage bud becomes flower

Rooting Hormones Cuttings Root – promoting hormones Indoleacetic acid (IAA), natural Other forms of this rooting compound used commercially