Plants are living things that make their own food from sunlight — let's explore how they do it!
Parts of a Plant
Every part of a plant has a specific job to do. Working together, these parts allow the plant to absorb water and nutrients, make food from sunlight, reproduce, and spread to new locations.
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Leaves
Food Factory
Make food through photosynthesis — absorbing sunlight with green chlorophyll
Have tiny pores called stomata that open and close to exchange gases
Release oxygen as a "waste product" of photosynthesis — the air we breathe!
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Stem
Support & Transport
Acts as a highway, carrying water and minerals up from roots to leaves
Carries sugars made in the leaves back down to the roots for storage
Holds the plant upright — can be soft and green (herbaceous) or hard and woody
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Flower
Reproduction
Attracts pollinators (bees, butterflies, hummingbirds) with color, scent, and nectar
Contains the stamen and pistil — the parts that make seeds
After pollination, the flower develops into a fruit containing seeds
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Fruit
Seed Protector
Develops from the flower after pollination — surrounds and protects the seeds
Animals eat fruit and then deposit seeds elsewhere in their droppings — spreading the plant
Comes in thousands of varieties — berries, nuts, pods, capsules, and the fruits we eat
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Seed
New Life Begins
Contains a tiny embryo plant plus a food supply to fuel germination
Travels to new locations by wind, water, animals, or explosion
Can stay dormant for years (sometimes decades!) until conditions are right to germinate
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Roots
Anchor & Absorber
Absorb water and dissolved minerals from the soil through tiny root hairs
Anchor the plant firmly in the soil so it isn't blown over
Can grow deeper than the plant is tall — some trees have roots 20+ feet deep
Photosynthesis: How Plants Make Food
Photosynthesis is one of the most important chemical reactions on Earth. It's the process by which plants (and algae) convert light energy into chemical energy stored as sugar. Here's the simple equation:
Chlorophyll — the green pigment in leaves — captures sunlight. The plant absorbs water through its roots and carbon dioxide through its leaves. Using the sun's energy, it combines these ingredients to make glucose (a sugar the plant uses for energy and growth) and releases oxygen as a byproduct. That oxygen is what we breathe!
What Plants Need to Survive
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Sunlight
Energy Source
The primary energy source for photosynthesis
Different plants need different amounts — some thrive in full sun, others in shade
Plants grow toward light — a phenomenon called phototropism
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Water
Essential Ingredient
Used directly in photosynthesis to make glucose
Keeps cells firm and upright — without water, plants wilt
Carries dissolved nutrients from soil up through the stem to leaves
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Soil & Nutrients
Mineral Supply
Provides nitrogen, phosphorus, potassium, and other essential minerals
Anchors the plant's root system and holds water near the roots
Some plants (like orchids) grow on other plants or in water instead of soil
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Air (CO₂)
Carbon Source
Carbon dioxide enters through stomata (tiny pores in leaves)
Carbon makes up the backbone of all organic molecules in the plant
Plants are natural carbon sinks — they remove CO₂ from the atmosphere
The Plant Life Cycle
Most flowering plants go through the same stages of life — from seed to mature plant and back to seed again.
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1. Seed
Starting Point
A dormant embryo plant with a built-in food supply (endosperm)
Protected by a hard seed coat until conditions are right
Needs warmth, moisture, and sometimes light to begin germinating
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2. Germination
Sprouting
The seed absorbs water and the embryo begins to grow
The root (radicle) pushes down and the shoot pushes up toward light
The seed's food supply powers the plant until it can photosynthesize
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3. Seedling
Young Plant
First true leaves appear and begin photosynthesizing
Roots grow deeper to anchor the plant and find water
Most vulnerable stage — susceptible to drought, pests, and frost
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4. Mature Plant
Full Growth
Fully developed root system, stem, and leaf canopy
Produces flowers to attract pollinators for reproduction
Stores energy in roots, fruits, and seeds for future growth
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5. Pollination
Seed Making
Pollen travels from one flower to another via insects, wind, or water
Pollen reaches the pistil so the flower can start making seeds
A seed forms and grows inside a fruit
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6. Seed Dispersal
New Beginnings
Seeds leave the parent plant by wind, water, animals, or mechanical means
Landing in a new location, seeds wait for the right conditions
The cycle begins again — one plant can produce thousands of seeds in its lifetime
🌳 One Tree's Impact
A single large tree can absorb up to 48 pounds of carbon dioxide per year and release enough oxygen for 2 people to breathe. Over its lifetime, a mature oak tree might produce 70,000 acorns — each one a potential new tree. Trees also cool their surroundings through transpiration, stabilize soil against erosion, and provide habitat for hundreds of species.
Plant Growth Facts
30%
of Earth's land surface is covered by plants — forests, grasslands, wetlands, and farms
48 lbs
of CO₂ a large tree absorbs per year — producing enough oxygen for 2 people
200 ft
Depth the deepest tree roots have been found — a wild fig tree in the Transvaal, South Africa
35 in/day
Growth rate of bamboo — the fastest growing plant on Earth, up to 3 feet per day!
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