Complete Flowers

All about Angiosperms

  • Flowers: a reproductive shoot (a twig plus leaves) of angiosperms

  • What is an angiosperm?

    • ā€œcovered seedā€

      • bear seeds which are inside an ovary

    • Angiosperms are the most highly evolved and most successful plants

      • 88% of the plant kingdom is made up of angiosperms, flowering plants

  • What is a gymnosperm?

    • ā€œnaked seedā€

Flowers and flowering plants

  • Flowers produce and disperse seeds

  • Sexual reproduction promotes superior plants

  • Four blasic flower parts

    • gynoecium: old nameā€”pistil, has one to many carpels (female part)

    • androecium: old nameā€”stamen, anther with pollen sacs, carries sperm (male part)

    • petals: help pollinators finds flowers

    • sepals: help cover or protect flower parts while they are in bud

  • Complete flowers have all 4 flower parts

  • More primitive flowers have complete parts

Gynoecium (one to many carpels)

  • Carpel = stigma, style, and ovary

    • stigma: where pollen needs to land

    • style: sorts out foreign pollen, stops growth of foreign pollen

    • ovary: contains ovules. Once fertilized, they develop into seeds

Androecium = stamens

  • Stamen: male floral parts containing pollen for fertilization

    • anther: contains pollen sacs

    • filament: stalk that supports anthers

Collective flower parts

  • calyx: all the sepals together

  • corolla: all the petals together

  • [perianth - calyx + corolla]

  • androecium: all the stamens

  • gynoecium: all the carpels

Complete flowers, which are more primitive, have all 4 flower parts.

Flower evolution:

  • Some families have not changed much from original ancestors

    • Characteristics: many petals, many stamens

    • Ex: Magnoliaceae, Lauraceae, Calycanthaceae, Annonaceae

  • Most of these are insect or animal-pollinated

  • Some families are more evolved

    • Characteristics: fewer number of flower parts (usually 5), more evolved floral structures