ENVIRONMENT

Mountain ash trees growing on the Australian island of Tasmania are the tallest flowering trees in the world. They are not quite the tallest trees of any kind, however—that record belongs to the coast redwoods of California. But that might be because things have been skewed against the mountain ash. (BBC)

Use our resources to learn more about the tallest trees in the world.

Teachers, scroll down for a short list of key resources in our Teachers’ Toolkit.

Discussion Ideas

• Tasmania’s mountain ash trees are not actually ash trees! They are a species of eucalyptus. What is a popular nickname for eucalyptus trees?
  • Some eucalyptus are nicknamed “gum trees” for their thick sap. Eucalyptus trees are the most abundant trees in Australia, which is where Tasmania is located.
  • (FYI: Ash trees are native to Europe, Asia, and South America. They are related to olive trees.)

 

• The BBC article says mountain ash are the tallest species of “flowering tree.” What is a flowering tree?
  • A tree is a type of plant, and a flowering plant is simply a plant that produces flowers. (Flowers are reproductive organs of flowering plants.) Flowering plants, which make up about 90% of all plant life, are also known as angiosperms.
  • “White flowers like pom-poms dot the upper part of the crown [of the mountain ash], which can stretch 75 meters (246 feet!) deep.”

 

• Coast redwoods are not flowering trees. What species of plant are they?
  • Coast redwoods are conifers, meaning they produce cones, not flowers, as part of their reproductive process.

 

• The BBC article says that while coast redwoods are definitely the tallest trees in the world right now, some environmental conditions may “have been skewed against the mountain ash.” How?
  • “It turns out that humans have been cutting them down in their prime . . . If conditions improve, [the trees] might they one day beat out the redwoods.”

 

• Read through the BBC article on mountain ash, and our own article on redwoods in Humboldt County, California. Botanists in Tasmania and California have named “their” trees, just like pet owners name their pets! What are some of the nicknames of Tasmania’s mountain ash giants? What are the nicknames of California’s giant redwoods?
  • Tasmania: Centurion, Damocles, El Grande, Medusa
  • California: Dyerville Giant, Hyperion Tree, Stratosphere Giant

 

• Both the mountain ash and coast redwoods are vital parts of forest ecosystems. What are some animals indigenous to eucalyptus and redwood forests?
  • eucalyptus: wedge-tailed eagles, Leadbeater’s possum, reptiles, insects, frogs. Learn more about eucalypt forests from the good folks at Tasmania’s Parks and Wildlife Services here.
  • redwood: bats, murrelets (an endangered seabird), insects, skunks, foxes. Learn more about redwood forests from the good folks at the U.S. National Park Service here.

 

• Why do some botanists and ecologists think that, given the chance, mountain ash may eventually grow taller than coast redwoods?
  • Mountain ash “grow five times faster than the redwoods, ‘sprinting’ toward the skies. ‘They’re the fastest-growing tree by far,’ says one scientist. ‘Plant a eucalyptus and it can grow 90m in 90 years.'”

 

• So, coast redwoods are the current record-holders for “world’s tallest tree,” but the mountain ash may take that record a short century or two. Which of the species lives longer?
  • Coast redwoods, definitely! Redwoods can live for more than 2,000 years. Mountain ash may grow to 500 years.
  • (FYI: Both mountain ash and coast redwoods are babies compared to the oldest trees in the world, bristlecone pines native to North America. In fact, bristlecone pines are among the oldest living things on Earth—as old as 5,000 years!)

 

• Both the BBC and Nat Geo articles list some threats to tall trees as lack of water resources, winds, and toxic fungi. What is the single biggest threat to both mountain ash and coast redwoods?
  • Human activity. Both mountain ash and redwood forests have been extensively logged for their high-quality lumber.

 

TEACHERS’ TOOLKIT

BBC: Tasmania’s giant ash trees may be the world’s tallest

Nat Geo: Tall Trees

Parks and Wildlife Services, Tasmania: Eucalypt Forests

National Park Service: Redwood National and State Parks