Tree

TREE PHYSIOLOGY

* A tree is a tall plant with woody tissue. Trees gather light for photosynthesis through their leaves; this process creates “food” for the tree.

* Most of a tree trunk is dead tissue and serves only to support the weight of the tree crown. The outside layers of the tree trunk are the only living portion. The cambium produces new wood and new bark.

* The band of tissue outside of the cambium is the phloem. Phloem transports new materials (the sugars created from photosynthesis) from the crown to the roots. Dead phloem tissue becomes the bark of a tree.

* The band of tissue just inside of the cambium is the xylem, which transports water from the roots to the crown. Dead xylem tissue forms the heartwood, or the wood we use for many different purposes.

*Every year, trees grow two annual rings. In the spring, usually a wider and thinner-walled layer called springwood forms. In the summer, a thicker-walled layer, called summerwood, develops. Annual rings are typical in temperate forest trees.

PARTS OF A TREE

* Leaves – broadleaf or needles; primary location for photosynthesis and production of hormones and other chemicals.
* Twigs and Branches – support structures for leaves, flowers and fruits.
* Crown – the upper part of the tree composed of leaves, twigs, branches, flowers and fruit.
* Flowers – the site of reproduction. Trees can be male, female or both. Conifers, however, do not have petals and typical flower structures.
* Fruits and Seeds – all trees have seeds, most are inside of the fruit.
* Trunk – generally a single “stem,” but can be multiple-stemmed. Main functions are materials transport and support.
* Bark – main function is to protect the living tissue called cambium from damage.
* Roots – two main functions: (1) collect nutrients and water and (2) anchor the tree

TREES GROW

* At the twig tips (apical meristem)
* At the root tips (root apical meristem)
* At the cambium (old xylem cells become heartwood, old phloem cells become bark)

USES OF TREES

• Trees for food

• Lumber and paper

• Fire wood

• Shade

• Beauty and interest

• Wind break, sound barrier and privacy

• Medicine and cooking