Trees & Forests – What is a tree? Science 6

What is a tree? A tree is defined according to the following criteria: It must be perennial It must have a self supporting trunk The trunk must be made of woody material A tree usually grows to a height of 5 to 7 metres NOTE: a young tree that has not yet reached adult height is called a sapling.

Difference Between Plants & Trees All other plants differ from trees in at least one of these ways. No plant with a soft, juicy stem is a tree. Most plants are much shorter than trees. Shrubs, like trees, have woody stems; but most shrubs have more than one stem, none of the stems grow so thick as to be called a trunk. Some jungle vines grow several hundred metres long and have a woody stem. However, the stems of vines cannot support themselves.

What is a tree? Trees are the largest of all plants. The tallest trees grow higher than 30-story buildings. Many trees also live longer than other plants. Some live for hundreds or even thousands of years. They are the oldest known living things.

What is a tree? Trees continue to grow as long as they live. Each year a new layer of wood is added to the trunk of the tree. Trees rest during the winter months. Trees in this state are called dormant.

Similarities & Difference Between Plants & Trees Using a Venn Diagram as a class we’ll come up with differences and similarities between Plants & Trees Characteristics of a Tree on the left side Characteristics of a Plant on the right side Similarities between the two go in the middle

Crown Roots Parts of a Tree Outer Bark Inner Bark Cambium Sapwood Heartwood Roots

Parts of a Tree (Definitions) Roots: anchor the tree in the ground and absorb water and minerals from the soil. Trunk: strongest part of the tree providing support for the rest of the tree Outer Bark (cork): outer part of the trunk; is dead tissue; protects the living parts underneath.

Parts of a Tree (Definitions) Branch: lateral extension of the trunk that grows leaves, flowers, fruit and seeds. Needles or Leaves: flat or needle-like structures containing most of the chlorophyll and are the main sites of photosynthesis. Use sunlight, water and carbon dioxide to produce food for the trees and free oxygen gas.

Parts of a Tree (Definitions) Cones: small woody structures which produce seeds on coniferous trees Crown: the upper part of a tree made up of branches, twigs, leaves, needles, buds and cones. Xylem: hollow cells that transport water and minerals from the roots throughout the tree make up the wood of the tree.

Parts of a Tree (Definitions) Phloem: tissue that moves sap up and down a tree, makes up the inner bark or layer next to the outer bark; transports nutrients made in the trees leaves down to the roots. The tree will die if this layer is damaged. Cambium: thin yellowish white layer found between the sapwood and inner bark which produces new xylem cells (wood) every year, allowing the tree to grow.

Parts of a Tree (Definitions) Heartwood: non-living core of tree stem, giving the stem strength. Heartwood makes up the most of the stem. Sapwood: a relatively thin layer of active xylem or wood that surrounds the heartwood. This is where the water and dissolved nutrients are transported through cells called the xylem, from the roots to the leaves.