Arbor Day

2. The flattened structure of a higher plant, typically green and blade-like, attached to a stem.
6. The area of partial darkness or coolness caused by the blocking of sunlight.
9. The upper layer of branches in a forest, formed by the crowns of the trees.
10. The surroundings or conditions in which a person, animal, or plant lives or operates.
11. The color of growing foliage, grass, and other plants.
12. A colorless, odorless reactive gas, essential for respiration in plants and animals.
13. The careful preservation and protection of natural resources.
15. The process of increasing in physical size.
17. The tough protective outer sheath of the trunk, branches, and twigs of a tree.

1. The act of putting seeds, young plants, or trees into the ground to grow.
3. A tall, woody perennial plant with a single main stem or trunk and many branches.
4. The planet on which we live; the third planet from the sun in our solar system.
5. A young plant that grows from a seed.
6. A flowering plant's unit of reproduction, capable of developing into another such plant.
7. A large area covered chiefly with trees and undergrowth.
8. A young tree, especially one with a slender trunk.
14. The part of a plant that attaches it to the ground and gathers water and nutrients.
16. The main stem of a tree, typically upright, supporting branches and leaves.