Woody plant
Encyclopedia
A woody plant is a plant
that uses wood
as its structural tissue. These are typically perennial plants whose stems and larger roots are reinforced with wood produced adjacent to the vascular tissue
s. The main stem, larger branches, and roots of these plants are usually covered by a layer of thickened bark
. Woody plants are usually either tree
s, shrub
s, or liana
s. Wood is a structural cell
ular adaptation that allows woody plants to grow from above ground stems year after year, thus making some woody plants the largest and tallest plants.
A plant with true woody stems contains wood
, which is primarily composed of structures made of cellulose
and lignin
. These structures provide support and a vascular
system which woody plants use to move water and nutrients from the roots to the leaves and to move sugars from the leaves to the rest of the plant. Most woody plants form new layers of woody tissue each year, and so increase their stem diameter from year to year. New wood is deposited on both sides of a vascular cambium
layer that is present near the outer parts of the stem; under the bark on most plants. In some monocotyledons such as palms
and dracaenas, the wood is formed in bundles from meristem
cells within the trunk. In palms, the wood is formed in the center of the stems. The dermal layer has been modified to protect the stems from the elements with a thickened covering of dead tissue, generally called bark.
Some annual plants appear to form woody stems in their first year, but die at the end of the growing season. They are herbaceous
stems without the dead bark covering.
Woody herb
s are herbaceous plants that do not have the thickened bark covering, but develop hard stems with vascular bundles. They include such plants as Uraria picta and certain species in family Polygonaceae
. These herbs are not truly woody but have hard densely packed stem tissue. Other herbaceous plants have woody stems called a caudex
, which is a thickened stem base often found in plants that grow in alpine
or dry environments.
Under specific conditions, woody plants may decay
or may in time
become petrified wood
.
The symbol for a woody plant, based on Species Plantarum
by Linnaeus is
, which is also the astronomical symbol for the planet Saturn
.
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
that uses wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
as its structural tissue. These are typically perennial plants whose stems and larger roots are reinforced with wood produced adjacent to the vascular tissue
Vascular tissue
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue:...
s. The main stem, larger branches, and roots of these plants are usually covered by a layer of thickened bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
. Woody plants are usually either tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s, or liana
Liana
A liana is any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy to get access to well-lit areas of the forest. Lianas are especially characteristic of tropical moist deciduous...
s. Wood is a structural cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
ular adaptation that allows woody plants to grow from above ground stems year after year, thus making some woody plants the largest and tallest plants.
A plant with true woody stems contains wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
, which is primarily composed of structures made of cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
and lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
. These structures provide support and a vascular
Vascular tissue
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue:...
system which woody plants use to move water and nutrients from the roots to the leaves and to move sugars from the leaves to the rest of the plant. Most woody plants form new layers of woody tissue each year, and so increase their stem diameter from year to year. New wood is deposited on both sides of a vascular cambium
Vascular cambium
The vascular cambium is a part of the morphology of plants. It consists of cells that are partly specialized, for the tissues that transport water solutions, but have not reached any of the final forms that occur in their branch of the specialization graph...
layer that is present near the outer parts of the stem; under the bark on most plants. In some monocotyledons such as palms
Arecaceae
Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates...
and dracaenas, the wood is formed in bundles from meristem
Meristem
A meristem is the tissue in most plants consisting of undifferentiated cells , found in zones of the plant where growth can take place....
cells within the trunk. In palms, the wood is formed in the center of the stems. The dermal layer has been modified to protect the stems from the elements with a thickened covering of dead tissue, generally called bark.
Some annual plants appear to form woody stems in their first year, but die at the end of the growing season. They are herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
stems without the dead bark covering.
Woody herb
Herb
Except in botanical usage, an herb is "any plant with leaves, seeds, or flowers used for flavoring, food, medicine, or perfume" or "a part of such a plant as used in cooking"...
s are herbaceous plants that do not have the thickened bark covering, but develop hard stems with vascular bundles. They include such plants as Uraria picta and certain species in family Polygonaceae
Polygonaceae
Polygonaceae is a family of flowering plants known informally as the "knotweed family" or "smartweed family"— "buckwheat family" in the United States. The name is based on the genus Polygonum and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name refers...
. These herbs are not truly woody but have hard densely packed stem tissue. Other herbaceous plants have woody stems called a caudex
Caudex
A caudex is a form of stem morphology appearing as a thickened, short, perennial stem that is either underground or near ground level . It may be swollen for the purpose of water storage, especially in xerophytes...
, which is a thickened stem base often found in plants that grow in alpine
Alpine climate
Alpine climate is the average weather for a region above the tree line. This climate is also referred to as mountain climate or highland climate....
or dry environments.
Under specific conditions, woody plants may decay
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
or may in time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....
become petrified wood
Petrified wood
Petrified wood is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree having turned completely into stone by the process of permineralization...
.
The symbol for a woody plant, based on Species Plantarum
Species Plantarum
Species Plantarum was first published in 1753, as a two-volume work by Carl Linnaeus. Its prime importance is perhaps that it is the primary starting point of plant nomenclature as it exists today. This means that the first names to be considered validly published in botany are those that appear...
by Linnaeus is
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
.