98 Plants: Supplemental Guide 3C | The Life Cycle of a Plant
Show image 3A-9: Dead tree
Some oak trees can live for two hundred years. But eventually, like all
living things, the oak tree will die. The oak tree does not die suddenly
but slowly over the course of several years. Show image 3A-10: Decomposition
Tell your partner about the last part of an oak tree’s life cycle. Use
the words decay, soil, and nutrients while you tell about it.[Allow thirty seconds for students to talk. Call on a volunteer to explain.]
The tree 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.Finally, the roots will die and the tree will fall down with a big crash
on the forest floor. The tree’s branches will be the first to rot and
disappear into the soil. But it will take many years for the woody trunk
to completely decay and break down into little pieces and go back
into the soil.All of the nutrients in the wood will become part of the soil once
again.Why are decayed plants good for the soil?- The more decayed plants there are in the soil, the more nutrients that soil
will have.
The more nutrients there are, the easier it will be for new seeds, like
the acorn seeds, to germinate and grow. And a new life cycle of an
oak tree begins!
Show image 3A-11: Life cycle of a sunflower
As we have seen, all plants live according to a life cycle. This diagram
shows you the life cycle of a sunflower.Explain the life cycle of a sunflower to your partner.[Allow one minute for students to talk. Students may use Response Card 2. Call
on a different student to talk about each stage in the life cycle.]- A new plant begins when the sunflower seed germinates and sprouts to
become a seedling. If the seedling receives the right amount of water,
nutrients, and light, the plant will continue to grow. Eventually, the plant