What is a Tree?• A tree is a large, woody plant that has a

single, sturdy stem, or trunk, and that grows taller than most other plants.

What About Shrubs & Bushes?

• Shrubs and bushes are much smaller and have several stems instead of a single trunk.

Basic Parts of a Tree

• Crown

• Trunk

• Root System

• Gathers sunlight, makes food for growth, helps filter air, produces oxygen.

• Supports crown, carries water and nutrients to crown, carries food back to roots.

• Anchors tree, collects water and nutrients from soil, helps hold soil in place.

CROWN

• Leaves

– breathing pores• Takes in carbon

dioxide and releases oxygen during photosynthesis.

– solar panels• Takes in light energy

and heat in order for photosynthesis to occur.

TRUNK

• Inner Bark– Phloem (arteries)

• Carries food from the leaves down to the stem and roots.

• Cambium– Phloem & xylem cells are

made in this single cell layer.

• Sapwood– Xylem (veins)

• Transports water, minerals and food upward from the roots to the leaves and horizontally across the stem.

ROOTS

• Root Tips & Hairs– absorb water and

minerals from the soil that are used in photosynthesis

Classifying Trees

• Gymnosperm– gymnos – “naked”– sperma – “seed”

• Coniferous (softwood)– Cone-bearing Trees

• needle-like leaves• scale-like leaves

– most stay green all year

• Angiosperm– angeion – “case”– sperma – “seed”

• Deciduous (hardwood)– Flowering Trees

• wide, flat leaves– fall off in autumn

How Old is That Tree?

• Every year a tree’s trunk grows wider, and each year’s growth appears as a ring.

• The approximate age of the tree can be determined by counting the annual growth rings.

• Springwood – wider, lighter part of the ring made up of cells that are added in the spring, when the tree grows rapidly.

• Summerwood – thinner, darker part of the ring formed during the rest of the year, when the tree grows more slowly.

Counting Growth Rings

• Start at the center ring (first year of growth) and count outward towards the bark.

• Close rings– Slow growth

• Dry year• Limited water

• Wider bands– Faster growth

• Wetter year• Optimal growing

conditions

The Value of Trees• Can you identify 4 reasons why trees should be valued

as one of our most important natural resources?

Habitats for wildlife

Recreational use

Products and by-products

Filters air