Use Case

Picture of CI-202 Portable Laser Leaf Area Meter


Portable Laser Leaf Area Meter

Picture of CI-203 Handheld Laser Leaf Area Meter


Handheld Laser Leaf Area Meter

What are leaves and why are they important?

Aug. 18, 2016

As a research scientist, you’ve dedicated your life to understanding and communicating details about plants that others haven’t considered in the past. Our infographic below focuses on the leaf basics: what leaves are, what they do, and why they are so important.  

Share it with your students, your friends and family, or just use it as a reminder of why you do what you do.

Plus, check out the bottom to see 5 reasons to measure leaf area!

*Hint: Click the infographic to see a larger version. Not a fan of infographics? Jump to the bottom for a verbal copy.

What are leaves and why are they important?

A leaf is a plant organ, exposed to the external environment. Leaves are the primary way plants interact with the atmosphere and take care of their basic needs.

Food: Plants don’t eat food (heterotrophic)—they make it (autotrophic) by taking atmospheric CO2, water from the soil, and energy from light to make simple sugars in a process called photosynthesis.

  1. The chlorophyll molecule, responsible for the green color in leaves, is made of carbon and nitrogen, and acts as the antennae to initiate photosynthesis.
  2. Light excites the chlorophyll molecule and starts a chain reaction:
    1. Atmospheric CO2 enters the leaf and is “fixed” during photosynthesis to create simple sugars that plants (as well as humans and animals) use as building blocks for complex molecules.
    2. Light speeds up photosynthetic rate. 

Water is a critical molecule/substrate in most molecular processes. It’s also the main fluid for sugar/carbon transport in the plant.

  1. Pores on the leaf called stomata open and close to regulate photosynthetic rate and water loss
  2. Air is drier than the inside of a leaf. When stomata open, water molecules evaporate out of the leaf in a process called transpiration.
    1. Note: Most plants are water limited, and try to conserve water by closing their stomata during high wind periods or when the soil is dry.

A balancing act: The area that plants invest in leaves comes down to how much leaf surface they want to expose in order to maximize the rate of photosynthesis, and how much water they can “afford” to lose to the atmosphere through transpiration.

  1. The amount of tissue the plant “decides” to expose to the environment is called Leaf Area.
  2. Using a Leaf Area Meter, such as the CI-202 Portable Laser Leaf Area Meter or the CI-203 Handheld Laser Leaf Area Meter, scientists and farmers can observe the ways in which plants are adapting to their environment.

Alocasia and other tropical shade plants:

  1. Have huge leaves to capture any photons of light that might make it down to the forest floor, through the tall canopy and many layers of vegetation
  2. Are DARK green, with tons of chlorophyll so that they can maximize photosynthesis/carbon fixation
  3. Are thin! Water is abundant in the tropics, so the leaves can have a large surface area where water can evaporate

Desert or Mediterranean plants:

  1. Have leaves that are round and long, and often point upwards in order to limit light exposure and prevent burning in the constant sunlight
  2. Have white and grey waxes and/or hairs overtop of their leaves so they can reflect the light, like sunscreen! These hairs also minimize water loss due to wind blowing over the leaves and sucking water out of the open stomata
  3. Need to conserve water, so typically leaves are thicker and leaf tissue stores water

5 Questions a Leaf Area Meter can help you answer! 

  1. What does leaf shape infer about the environment the leaf is found in?
  2. How does removing forest canopy impact leaf area of understory plants?
  3. How does geography or elevation impact size/perimeter of leaves (typically they get smaller, more lobed further up and further north).
  4. How does drought stress impact the leaf area (ultimately photosynthetic area) of important crop plants?
  5. How can environments be manipulated to maximize leaf/photosynthetic/edible(?) area? 

Who uses a leaf area meter?

  • As a teaching or research tool for ecophysiologists
  • Phylogeneticists and Botanists – to bolster genetic work with data about physical and phenotypic changes in the plant
  • Agronomists who are trying to maximize yield through increase in photosynthesis – a way to measure their efforts