I. Plant Life Cycles
- life cycle: stages through which a living thing passes during its life
A. All living things:
1. change, usually beginning as something small and growing bigger
2. they reproduce to make more of the same kind
3. eventually they die
- Most plants go through similar stages during their life cycles
- Differences in life cycles can include the way they reproduce: seeds, spores, or cones
II. Life Cycle of a Flowering Plant:
- Example: Pumpkin
1. Germinating seed: happens when water, oxygen, and warm temperatures are present, stem grows up, roots grow down
2. Growth: leaves grow & the plant makes sugar, it grows into an adult plant with flowers
3. Pollination: some flowers make pollen, other flowers use that pollen to make seeds
4. Adult Plant with Seeds: a fruit (pumpkin) is made/grown, the fruit has seeds inside, those seeds can become new plants
III. Life Cycle of a Conifer Plant:
- Example: Pine trees
1. Germinating seed: happens when water, oxygen, and warm temperatures are present, a seedling grows from the germinating seed
2. Growth: takes many years, grows into a tall adult tree, makes small pollen cones & large seed cones
3. Pollination: small pollen cones make pollen, wind carries the pollen to the large cones, where seeds are made
4. Adult Plant with Seeds: seeds develop in the seed cones, then seeds fall to the ground when the cones open, those seeds can become new plants
IV. Other Plant Life Cycles
1. Some plants have 2 kinds of life cycles. They can make seeds AND:
A. use stems to grow a new plant (ex: strawberries)
B. use roots to grow a new plant (ex: dandelions)
C. use leaves to grow a new plant (ex: Kalanchoe)
V. Plant life cycle lengths vary greatly
- Some take only a few weeks and others will have a one- or two-year life cycle
- Trees live for a significantly longer time (175-3,000 years)
Ideas to reflect on:
- How are the life cycles of flowering plants and conifer plants alike?
- How do plants grow and change?
- Will a fern and a flowering plant have the same life cycle?
- Why do plants need to attract bees, hummingbirds, or butterflies to them?
- What do you think causes some desert plants to have such a short life cycle?
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