1. Leaf Reflectance & Absorption

2. “Pimple” Savanna forms from termite mounds in innundated tropical grasslands Leaf Reflectance & Absorption

3. Beltsville winter wheat

4. True & False Color Photos In true-color, grass and astroturf look similar; in the near-infrared, grass is more reflective grass astroturf astroturf grass True color film Color infrared film

5. Plant Pigments So, what absorbs in functioning leaves? None of the key pigments absorbs green light; instead it is reflected to our eyes, which makes plants look green to us.

6. Liquid Water Absorption Liquid Water Absorption Liquid water in plant leaves completes the absorption picture: leaves must be hydrated for photosynthesis

7. Green Leaf Structure

8. Dicot and Conifer Leaves Bean leaf x420 Pine needle x370

9. Maple & Pine reflectance Maple & Pine reflectance maple pine Similar in visible light, different in the near-IR

10. Leaf Reflectance & Absorption Reflectance = 1.0 - Absorption Banana x1400Cucumber x490

11. Leaf Photosynthesis Photosynthesis Determines Optical Properties Bean leaf x4200

12. Leaf Photosynthesis Photosynthesis Determines Optical Properties Must capture photons to drive chemical reactions (energy input) Must be in presence of H2O Must be in presence of CO2 Must get rid of O2 (poisonous) Must live in hostile setting…

13. Internal Leaf Structure Chloroplasts Intercellular air labyrinth CO 2 in & O 2 out

14. Leaf Reflectance & Absorption Photosynthesis requires CO 2 from atmosphere to be in contact with the plant cell surfaces. The intercellular labyrinth allows movement of CO 2 into leaves and O 2 out. Part of the “deal” is H 2 O is lost

15. Leaf Photosynthesis Stomata regulate gas exchange and water loss CO 2 in/O 2 out

16. Leaf Photosynthesis Piers Seller’s PAR Diagram

17. Photosynthesis Action Spectrum