Plants: Supplemental Guide 3A | The Life Cycle of a Plant 83 Show image 3A-5: Acorn and oak
Now let’s explore the life cycle of another plant—an oak tree.Here’s an acorn that contains the seed of an oak tree. You may have
seen acorns before, lying next to full-grown trees or being carried
away in the mouths of squirrels. Show image 3A-6: Squirrel eating an acorn
Squirrels spend all day running around looking for food. They also
spend a lot of time hiding food. Squirrels bury so many acorns that
they forget where they put some of them. An acorn that the squirrel
forgets stays in the soil, giving the oak seed a better chance to
germinate underground.
Once the seed sprouts, it will quickly grow into a seedling, but the
young tree will grow only a foot or two in its first year.[Show students what one or two feet look like by using a ruler or yardstick.] Show image 3A-7: Young oak
After a few years, it will turn into a sapling—a young tree. A sapling
can grow to be over ten feet, but it is still considered a young tree.
This tree will still be called a sapling for many years.[Have students say sapling with you three times. Estimate how tall ten feet can
be for students. Emphasize that even though a tree may be tall, it might still be
considered a young tree.] Show image 3A-8: Mature oak
Oak trees take a long time to mature—or grow into adult or full-grown
trees. In fact, it takes about fifty years for an oak tree to mature and
be able to make a lot of acorns. An oak tree can produce over ten
thousand acorns in its lifetime. But only a few of those acorns will
germinate and grow into new oak trees. Show image 3A-9: Dead tree
Some oak trees can live for two hundred years. But eventually, like the
sunflower, the oak tree will die. The oak tree does not die suddenly
but slowly over many years. It will produce fewer and fewer leaves
each year, its branches will drop off one by one, and gradually its
wood will become softer and softer.