plant reproduction in angiosperms

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• Today's topic is the exciting process of plant reproduction in angiosperms.
• Angiosperms


  Flowering plants, some of the most successful and diverse plants around
• Many grasses, crops, and plants that produce fruit are flowering plants
• Fruit (biological definition)


  Develops from the ovary of a plant
• Pumpkins, green beans, tomatoes, squash are all fruits by the biological definition
• Vegetable


  Not a true biology definition, often refers to plant structures that are not as sweet
• Flowers of angiosperms


  • Contain male and/or female parts
• Stamen


  The male part of a flower, includes the filament and anther
• Filament


  Stalk that supports the anther
• Anther


  Fluffy structure that produces pollen
• Pistil


  The female part of a flower, made of the stigma, style, and ovary
• Stigma


  Sticky structure that pollen is supposed to stick to
• Style


  Stalk that supports the stigma
• Ovary


  Where fertilization occurs and seeds are formed, ripens into a fruit
• Sepals


  Protect a developing flower bud
• Petals


  Fancy structures that help attract pollinators
• Pollinator


  Organisms like hummingbirds, butterflies, and bees that transfer pollen
• Nectar


  Sugary sweet substance produced by many flowering plants, a great source of energy for pollinators
• Pollination


  Pollen is brushed from a pollinator onto the sticky stigma
• Pollen grain


  Consists of a tube cell and a generative cell
• Fertilization


  1. Tube cell burrows pollen tube from stigma to ovary

  2. Generative cell divides to form two sperm cells

  3. One sperm cell fertilizes the egg cell

  4. Second sperm cell joins the two polar nuclei to form the endosperm
• Fertilization in angiosperms is called double fertilization
• Fruit (in angiosperms)


  Surrounding ovary ripens and develops to help seeds travel far from parent plant
• Many angiosperm species only accept pollen from other plants, not their own anthers (self-pollination)
• Pollinators are crucial for crops all over the world, wind and other methods can only do so much
• The stamen consists of anther (pollen sac) and filament (stalk).