(Ginkgo Biloba ^)

The Evolution of Trees
It all starts in the water (500+ million years ago)
Life is simple: algae floating in the ocean.
Some start forming simple bodies, some stay microscopic.
Then something revolutionary happens:
Plants crawl onto land (≈ 470 million years ago)
These were tiny, moss-like, no roots, no wood, no leaves.
They hugged the ground to avoid drying out.
But the moment plants moved onto land, evolution had a whole new playground.

Vascular tissue evolves — the first “plumbing” (≈ 425 million years ago)
Two big inventions change everything:
xylem
Carries water upward.
Made of lignin → strong, rigid. This is where wood originates.
phloem
Carries sugars downward.
Plants get their first skeletons. Now they can grow tall.

The first “trees” appear (≈ 385 million years ago)
Meet:
Archaeopteris
The earliest real tree.
It had:
✓ wood
✓ branches
✓ deep roots
✓ a trunk up to 30 m tall
But… it reproduced by spores, like a fern.
No seeds yet.
These forests changed Earth’s atmosphere and created soil.

Seed plants evolve (≈ 360–320 million years ago)
This was huge.
Seeds = baby plant in a protective vault with nutrients.
Now plants can colonize dry habitats and survive seasons.
Two early seed groups appeared:
Gymnosperms (naked seeds — modern examples: pines, spruces, firs)
Seed ferns (now extinct)

The Age of Giants (Carboniferous Period)
Earth was swampy.
Oxygen was extremely high.
Trees exploded in size.
Dominant groups:
• tree-sized horsetails
• massive clubmoss trees (Lepidodendron, up to 40 m tall)
• early gymnosperms
They formed the forests that eventually became coal.

Conifers rise (≈ 300 million years ago)
Modern-style conifers evolve from gymnosperms.
Your familiar Ontario species originate from this lineage:
• white pine
• red pine
• spruce
• fir
• hemlock
• cedar
Conifers dominated for tens of millions of years — especially in cold, dry places.
They’re survivors.

Ginkgo and cycads appear (≈ 270–200 million years ago)
• Ginkgo → the “living fossil”
• Cycads → palm-like gymnosperms
They were everywhere during the dinosaur age.

Angiosperms (flowering trees) explode (≈ 140 million years ago)
Enter the flower.
This changed everything.
Angiosperms evolve fruits, nuts, berries — sweet rewards for animals.
Animals spread seeds → huge evolutionary advantage.
They diversify wildly, replacing many gymnosperms in warm climates.

These include:
Hardwoods / Broadleaf trees
Maples, oaks, beech, birch, cherry, ash, walnut, linden, poplar, willow — basically almost every leafy tree in Ontario.

Miocene to present (20 million years ago → now)
The climate is cool. Ice ages cycle.
What survives?
• Conifers in cold + high elevation
• Angiosperms in warm + temperate zones
• Boreal forests expand (spruce, pine, fir)
• Temperate hardwood forests shift south and north repeatedly
The result is the tree world we know today.

Reigning champions:
By diversity: angiosperms (flowering trees)
By cold-hardiness: conifers
By biomass: tropical rainforest angiosperms

Timeline (mya = million years ago)
470 mya – First land plants
425 mya – Vascular tissue
385 mya – First trees (spore-based)
360–320 mya – Seed plants
300 mya – Conifers
200 mya – Ginkgo + cycads
140 mya – Flowering trees
20 mya – Modern forests take shape