The ground-living plants are in a hurry.
Before long, the trees above will come into leaf and steal their light.
Their flowers decorate the forest floor
as they advertise their sweet nectar to the newly emerged insects.
The spring blooms of the deciduous woodlands have no equivalent
in either the great conifer forests or the tropical jungles.
Within a matter of weeks, the canopy has closed
and only a few wheeling shafts of light penetrate the woodland.
In the tree tops, the broad leaves rapidly expand to their full size
to make the most of summer while it lasts.
Then, after a few months, the days begin to shorten again
and the trees must shut down and shed their leaves
in preparation for the cold, dark time ahead.
Great tracts of North America flush red as the season progresses.
The effect is so spectacular and so extensive that it can be seen from space.
The threat of winter frost is not the only reason for trees to shed leaves.
These forests stand in the tropics.
Here, day length never changes.
But the dry season is so severe
that the trees can't afford to lose the amount of water
that would evaporate from their broad leaves,
so the leaves must be shed.
The forest resembles a European woodland in midwinter
but the heat is overpowering and its inhabitants unfamiliar.
For the creatures of India's teak forests these are desperate times.
But salvation is at hand.
The mahua tree is about to bloom.
Its flowers are full of liquid, making them irresistible.
The mahua is an oasis in a hot, dry desert.
Those that fly or climb are not the only ones to get a share.
Chital deer follow the Langur monkeys, collecting the flowers that fall.
The monkeys welcome the deer, for deer are unrivalled at spotting predators.
If they are relaxed, it must be safe to come down to the ground
and gather the food that lies there.
But it's not wise to travel far from the sentinels.
Tropical Madagascar, the wet season.
It's now that the baobab trees re-grow their leaves
and collect water to store in their huge trunks ready for the dry season ahead.