12.2 Review

Large main roots that go deep into the ground and frequently have secondary horizontal roots branching off the main root

• spreading roots

• fibrous roots

• taproot

Roots that grow from a plant's stem, branches, leaves, or mature woody roots

• aerial roots

• adventitious roots

• buttress roots

• prop roots

The main stem of a tree

The rough outer covering of a tree

The ring of growth cells that separates the bark layers from the woody tissues of a tree trunk

The growth of a stem in diameter

• primary growth

• secondary growth

The main tissue of the trunk

Made of large xylem vessels; light in color

• springwood

• summerwood

• heartwood

consists of small xylem vessels and is darker because of its closely compacted cells

• springwood

• summerwood

• heartwood

Inactive dead wood clogged with gummy deposits

• springwood

• summerwood

• heartwood