Plant Life Cycle

What Is the Life Cycle of a Plant?

Word of the Week

Germination

Germination is the initial development of a plant from a seed! During germination, tiny roots emerge from the seed followed by a stem that grows up towards the sun.

Species Spotlight

Great Basin Bristlecone Pine Tree

Pinus longaeva

The Great Basin bristlecone pine tree can live to be more than 4,000 years old, making it the oldest living organism in the world. This tree grows only on tall mountains in the southwestern portion of the United States where it spends its life battling wind, rain, and snow. Like other bristlecone pines, this species has a very slow life cycle and grows even slower (and lives longer) at higher elevations. It starts its life as a seed and can take hundreds of years to grow just a few feet tall. Great Basin bristlecone pines often grow out of nearly solid ground, which challenges germinating seeds and roots trying to expand. Even with the poor soil conditions, bristlecone pines have huge root systems that hold the tree upright during intense winter storms. As wind and freezing temperatures swirl around them, they often grow in a spiral pattern and develop twisted bark.

Like other pine trees, bristlecone pines produce seeds inside of woody cones. On tall mountains where Great Basin bristlecone grow, woodpeckers and other small animals rely on them for both food and shelter. Seeds are an important food source for these animals and, as they eat them and move around the mountainside, they spread the bristlecone seeds! If seeds end up somewhere with perfect conditions, they will germinate and a tiny bristlecone pine will form.

BRAIN BLAST

In 1964, the oldest tree in the entire world was cut down. Use this link to research what happened. Why was the tree cut down? How old was the tree? How did it change how we study trees?

Conservation Corner

GMOs & Plant Life Cycles

Genetically modified organisms (GMOs) are plants, animals, or other organisms that have had their DNA (or genes) altered by humans. Modifying an organism's DNA can affect things like its physical or behavioral traits, its growth rate, and its overall life cycle. Genetic modification is commonly used when growing food for humans, such as in fish hatcheries and on large farms, to produce more food faster. If we think of an apple tree, genetically modified trees will grow faster, produce fruit earlier in life, and produce larger apples. For those of us who like apples, this sounds great! However, there are many problems with GMOs.

On most farms, chemicals called herbicides are used to kill weeds growing near the crops. GM crops are not harmed by these herbicides because of the way they were designed. As farmers increase the use of herbicides (which doesn't hurt the crops), it kills native plants and can pollute the local environment and waterways. There is still debate about how GMOs affect human health, as well! The best way to reduce environmental harm from GMOs is to shop and eat organic.

Quiz

Quiz Printable

Organizing the Life Cycle of a Plant

Place the steps of a plant's life cycle in the correct order.

Plant Life Cycle Printable

Plant Life Cycle Challenge

Sunflower growth experiment

The best way to study the life cycle of a plant is to watch it happen! For this experiment, you will need...

Sunflower or wildflower seeds (a smaller variety will work best)
A sunny window or outdoor space depending on the season
A small pot
Soil
Water
3-4 months

Experiment steps:

Fill a small pot with soil.
Place 1-2 sunflower seeds in the soil ~1 inch deep.
Keep soil moist until germination.
After germination, reduce watering to every other day.
Each week, discuss or record your observations.
When the sunflower blooms, place outside for several days to allow pollination from bugs.
When the sunflowers produce seeds, start the experiment again!