botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

, the trunk (or bole) is the

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

and main

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

en axis of a

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that ar ...

, which is an important feature in tree identification, and which often differs markedly from the bottom of the trunk to the top, depending on the species. The trunk is the most important part of the tree for

timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...

production.

Occurrence

Trunks occur both in "true" woody plants and non-woody plants such as palms and other

monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of t ...

, though the internal physiology is different in each case. In all plants, trunks thicken over time due to the formation of

secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...

(or in monocots, pseudo-secondary growth). Trunks can be vulnerable to damage, including

sunburn Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is ...

Vocabulary

Trunks which are cut down for making

lumber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...

are generally called logs; if they are cut to a specific length, called bolts. The term "log" is informally used in

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

to describe any felled trunk not rooted in the ground, whose roots are detached. A stump is the part of a trunk remaining in the ground after the tree has been felled, or the earth-end of an uprooted tree which retains its un-earthed roots. Also is a growing green specimen that grows bananas

Structure of the trunk

The trunk consists of five main parts: The outer bark, inner bark (

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process i ...

), cambium, sapwood (live

xylem Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived fr ...

), and heartwood (dead xylem). From the outside of the tree working in: * The first layer is the outer bark; this is the protective outermost layer of the trunk. * Under this is the inner bark which is called the

. The phloem is how the tree transports nutrients from the roots to the shoots and vice versa. * The next layer is the cambium, a very thin layer of undifferentiated cells that divide to replenish the phloem cells on the outside and the xylem cells to the inside. The cambium contains the growth

meristem The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

of the trunk. * Directly inside of the cambium is the sapwood, or the live

cells. These cells transport the water through the tree. The xylem also stores starch inside the tree. * Finally at the center of the tree is the heartwood. The heartwood is made up of dead xylem cells that have been filled with resins and minerals; these keep other organisms from infecting and growing in the center of the tree. File:Timber floating.jpg, Raft of timber logs File:Corylus avellana12.jpg, Cross section of a

hazel The hazel (''Corylus'') is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,Germplasmgobills Information Network''Corylus''Rushforth, K. (1999) ...

bole File:A Lovely Rotting Log - geograph.org.uk - 998345.jpg, A de-barked log being decomposed by

bracket fungi Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside (see Delimitation for exceptions). They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all polypo ...

File:Olivenhain Alexandroupolis.jpg, Trunk / stump of a still-rooted

olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...

tree File:דקל תמר מצוי חתך גזע דמוי עץ (3).jpg, Trunk section from a

palm tree The Arecaceae is a family of perennial flowering plants in the monocot order Arecales. Their growth form can be climbers, shrubs, tree-like and stemless plants, all commonly known as palms. Those having a tree-like form are called palm ...

(the

date palm ''Phoenix dactylifera'', commonly known as date or date palm, is a flowering plant species in the palm family, Arecaceae, cultivated for its edible sweet fruit called dates. The species is widely cultivated across northern Africa, the Middle Eas ...

, ''

Phoenix dactylifera ''Phoenix dactylifera'', commonly known as date or date palm, is a flowering plant species in the palm family, Arecaceae, cultivated for its edible sweet fruit called dates. The species is widely cultivated across northern Africa, the Middle Eas ...

''). File:A ponderosa trunk.jpg,

References

External links

* Plant morphology de:Baum#Aufbau des Baumstammes {{tree-stub

Occurrence

Vocabulary

Structure of the trunk

See also

References

External links