Day 326 – We know that leaves get their
green color from chlorophyll, but sometimes leaves appear red, such as on a
Japanese maple, or have variations of color throughout the leaves, such as
croton plants, so where does this come from? Most plants have other
pigments: carotenoids, which appear
yellow to orange, and anthocyanins, which range from red to purple, and these
pigments may dominate the appearance of the green chlorophyll. So chlorophyll
is still present and at work, its color is simply masked.
Day 327 – Flowers began changing the way
the world looked almost as soon as they appeared on Earth about 130 million
years ago, during the Cretaceous period. That's relatively recent in geologic
time: If all Earth's history were compressed into an hour, flowering plants
would exist for only the last 90 seconds. But once they took firm root about
100 million years ago, they swiftly diversified in an explosion of varieties
that established most of the flowering plant families of the modern world.
Day 328 - Today flowering plant species
outnumber by twenty to one those of ferns and cone-bearing trees, or conifers, which
had thrived for 200 million years before the first bloom appeared. As a food
source flowering plants provide us and the rest of the animal world with the
nourishment that is fundamental to our existence. In the words of Walter Judd,
a botanist at the University of Florida, "If it weren't for flowering
plants, we humans wouldn't be here."
Day 329 - Botanists call flowering plants
angiosperms, from the Greek words for "vessel" and "seed."
Unlike conifers, which produce seeds in open cones, angiosperms enclose their
seeds in fruit. Each fruit contains one or more carpels, hollow chambers that
protect and nourish the seeds. Slice a tomato in half, for instance, and you'll
find carpels. These structures are the defining trait of all angiosperms and
one key to the success of this huge plant group, which numbers some 235,000
species.
Day 330 - Just when and how did the first
flowering plants emerge? Charles Darwin pondered that question, and
paleobotanists are still searching for an answer. Throughout the 1990s
discoveries of fossilized flowers in Asia, Australia, Europe, and North America
offered important clues. At the same time the field of genetics brought a whole
new set of tools to the search. As a result, modern paleobotany has undergone a
boom not unlike the Cretaceous flower explosion itself. We are learning more
about flowering plants all the time.
