Diversification of Flowers

66 million years ago – present (Cenozoic)

What was the Earth like at the beginning of this period?

  • The Earth was relatively warm and stable at the end of the Mesozoic and the beginning of the Cenozoic.

  • The Earth had elevated oxygen levels, which may have allowed the gigantic size in animals

Why are the flowering plants so successful?

  • The flowering plants make-up about 90% of all plants on the Earth.

  • To say they dominate is an understatement.

  • The reason for their dominance is a hotly debated topic, and there are several possible ideas, which may all be the answer.

  • Below you will find some of the proposed ideas.

    1. First, the flowering plants appear to have a metabolism rate that is higher than most non-flowering plants. This quick germination and growth can easily allow angiosperms to out-compete gymnosperms in most warm habitats. Even without reproducing, the angiosperms are able to quickly creep over the land and colonize disturbed and new habitats.

    2. Next, unlike most gymnosperms or spore-bearing plants, the flowering plants have pollinators which help disperse pollen from flower to flower. This insect assistance can be much more effective than the wind-dispersed pollen found in most conifers, depending on the habitat.

    3. Lastly, the angiosperms also have the ability to disperse their seeds through animals. The creation of the fruit allows animal to receive nourishment, without damaging the young plants found in the seeds. As animals move about, they leave the young plants in a perfect environment of warmth, water and fertilizer.

What group of angiosperms are most diverse?

  • The largest group of flowering plants are the orchid, or Orchidaceae. The diversity of these amazing plants is near 30,000 species, inhabiting the tropics, temperate zone, and even the arctic.

Other plant families that are high in diversity are:

  • Daisy family (Asteraceae)

  • Grass family (Poaceae)

  • Bean family (Fabaceae)

What was the Earth like before this time?

  • To answer this question, go back to the previous section: Rise of the Flowering Plants