4、   In spring, many flowers begin blooming, on the ground and even high in the trees. Have the trees in your neighborhood burst into bloom yet?

   Most trees bloom in the spring. However, some trees bloom in the late winter. Others bloom during the spring and the summer.

  1    For example, Hurricane Katrina stripped (除去) the leave off many trees. Afterward, some of these trees started to flower, even though they would not normally flower in the fall.

  Sometimes, during mild winters, trees flower early. ___2___ .

    When it warms up again, the trees may start growing leaves, but they may not be able to produce fruit.

    Pollen is a fine golden dust from flowers. ____3___This is called pollination (授粉)。

    After the female part receives the pollen, it can make seeds.

    ___4___Other types have trees with only female flowers and trees with only male flowers.

When we think of flowering trees, we usually think of the bright, colorful trees that make spring scenes so special.

__5__ The trees need insects, birds or bats to carry the tree’s flower pollen to other flowers.

Other trees have such tiny blossoms that we rarely see them. These trees do not need to be noticed by animals, because the wind carries their pollen from tree to tree.

All trees have flowers. It is the flowers that make the seeds.

A．In order for a flower to make seeds, pollen from the male part must reach the female part

B．Some tree types have male and female flowers on the same tree.

C．Trees might also bloom when something goes wrong with their environment

D．Trees need a way to spread their seeds

    E．But if snow and ice come after the flowers are out, these flowers die

    F．People have come up with may ways to stop trees from bearing fruit.

G．These trees have big, showy flowers that attract animals.