TED-Ed: Valentin Hammoudi: How tall can a tree grow?

Californian sequoias are among the tallest trees, but they face height limitations due to the challenges of sap movement against gravity. Trees circulate two types of sap: phloem, which distributes sugars, and xylem, which carries nutrients. The movement of sap is driven by transpiration, capillary action, and root pressure. However, as trees grow taller, these processes become less efficient, leading to the hydraulic limitation hypothesis, which explains why trees have a maximum height. Researchers continue to study these limitations to understand the factors affecting tree growth.

What is the maximum recorded height of a sequoia tree?

• 100 meters

• 200 meters

• 130 meters

• 150 meters

Which type of sap is responsible for distributing sugars throughout the tree?

• Root sap

• Leaf sap

• Phloem sap

• Xylem sap

What process allows water to move from phloem to xylem at the tree's base?

• Capillary action

• Osmotic movement

• Transpiration

• Photosynthesis

Which force is NOT involved in helping xylem sap move up the tree?

• Photosynthesis

• Root pressure

• Capillary action

• Transpiration

What hypothesis explains the height limitation of trees?

• Photosynthesis limitation hypothesis

• Gravity limitation hypothesis

• Nutrient limitation hypothesis

• Hydraulic limitation hypothesis