I was lucky enough to live in San Francisco for a few years, and in my time there, I learned to appreciate the majesty and beauty of redwood trees, which can be found in a number of places in the Bay Area. If you ever have a chance to visit, I would highly recommend that you explore some of the local state parks to get to see these spectacular trees in real life.

Redwoods have a number of claims to fame, and if you don't already know about them, you should—because these trees are incredible.

Tallest trees in the world

Redwoods, particularly coast redwoods, or Sequoia sempervirens, are the tallest trees on the planet. They can reach heights of nearly 400 feet, which is roughly equivalent to a 37-story skyscraper—so high that, when standing at the bottom of a redwood, you can't see the top, even on a clear day.

The tallest trees in the world have been given names—because such enormous trees deserve equally grandiose names—and are, in order: Hyperion (~398 feet tall), Helios (~374 feet tall), Icarus (~371 feet tall), and Daedalus (~363 feet tall). Want to go see them for yourself? Good luck finding them. Apparently, the exact locations are kept secret to prevent vandalism.

These trees are able to grow to be so tall because they're ancient and because they're well adapted to their temperate, foggy climate. A typical redwood lives for 500 to 700 years, although some have been documented at more than 2,000 years old, meaning that some of the coast redwoods living today were alive during the time of the Roman Empire. Not only that, but coast redwoods have been on the planet for more than 240 million years. Let me say that again: 240 million years. That means they've been around since the time of dinosaurs, or maybe even earlier.



Most massive trees in the world

Giant sequoias, sometimes called Sierra redwoods, or Sequoiadendron giganteum, are the overall largest (by volume) trees on the planet. They can grow to be ~30 feet in diameter and more than 250 feet tall.

The title of world’s largest tree goes to General Sherman, a giant sequoia in Sequoia National Park with a volume of 52,508 cubic feet. General Sherman is ~275 feet tall, has a ~102-foot circumference, and weighs an incredible 2.7 million pounds, making it about as tall as a 26-story building, wider than most city streets, and heavier than 100 elephants. (I confess that I'm curious how scientists were able to determine the weight of the tree, since it's still firmly rooted in the ground. If you know this, please let me know in the comments!) After General Sherman, the second-largest tree is General Grant, clocking in at 46,608 cubic feet, ~268 feet tall, and ~107-foot circumference. A tree named President (shown in the video above) takes third place, at 45,148 cubic feet, ~241 feet tall, and 93 feet circumference.

It makes sense that giant sequoias grow even bigger than coast redwoods, because they can live even longer. Most live to around 3,000 years old (!!), with the oldest on record living more than 3,500 years.



They typically grow in "fairy rings"

Even though redwoods are massive, they have tiny cones of about 1 inch long to spread their seeds around. They have appropriately large root systems, though, often extending 100 miles and intertwining with the roots of other redwoods. These underground networks spread out from their source—typically a dead tree—and end up growing in circular clusters, sometimes called fairy rings or cathedral trees.

What's extra interesting about these tree circles is that, in instances when the trees grow out of the perimeter of a dead tree trunk (which accounts for about 80% of all living redwoods), the encircling trees all end up being genetic clones of that original tree. Cool, right? If you think about it, that means that some of today's redwoods could be the last in a 20,000- or 30,000-year (or more) line of the same tree reproducing itself over and over again.

Another way fairy circles can form is when baby redwoods sprout at their parents' base, latching onto their roots for nutrients. Because redwood seeds are so small compared to their mature size, it seems the sprouts don't wander too far from home. And having been lucky enough to see these trees with my own eyes, I can't really blame them.

Refrigerator trees

Although not technically redwoods themselves, Pacific madrone trees, or Arbutus menziesii—sometimes called madrona, bearberry, or strawberry trees—are an important part of redwood forests. These fascinating trees were introduced to me as "refrigerator trees," so called because of their eternally cool temperature, which I confess I didn't believe in until I tested it out for myself. But it's 100% true, and it's absolutely baffling to experience firsthand on a hot summer's day.

Madrone trees are easy to spot: they have smooth orange-red bark that peels and curls as it ages, eventually falling off and leaving its inner bark (typically a pale green) bare and visible. If you touch these bare spots, no matter how hot the day is, the bark will be cool to the touch.

What we don't seem to know yet is why madrones are cool to the touch. Trees have water running upward in the trunk just beneath the bark layer, so one park ranger hypothesized that when you’re touching the exposed part of a madrone you're actually touching areas of its vascular tissue, which is what moves water and nutrients through the tree. Another theory holds that madrone trees store so much water that their temperature is cooler than the air around them.



Redwoods need our help

A hundred years ago, the biggest threat to these incredible trees was logging: of the original redwood range, about a quarter—approximately 625,000 acres—was lost forever. Happily, the Save the Redwoods League has since preserved nearly 200,000 acres in dozens of redwoods parks and protected redwood forestland on private properties as well. Nowadays, threats to redwoods include things like climate change, forest fires, and real-estate development.

There's also the threat of burl poaching. Burls are hard, knotty growths that form from dormant seedlings on trunks of living trees, and their wood is highly valued for its beauty and rarity. The problem is that, when poachers come and cut off redwood burls, it leaves the tree exposed to infection and disease. Making matters even worse, burls actually contain infinite promise: if the original tree dies, its burl will blossom, sometimes even going on to become a full-grown redwood tree itself.

So how can you help? For starters, you can visit some of the redwoods state parks to show your support. If you live nearby, you can even volunteer or sign up to be a citizen scientist. If you're not local, there are other volunteering opportunities, or you can support the parks through donations. There are fun ways to get your kids involved, too, like this kids' art contest; for adults, there's an annual photo contest, plus free e-cards.

And, of course, you can spread the word about redwoods by sharing this post with your family and friends!