In
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 and main
wooden axis of a
tree, 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 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 ...
, though the internal physiology is different in each case. In all plants, trunks thicken over time due to the formation of
secondary growth (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 ho ...
.
Vocabulary
Trunks which are cut down for making
lumber are generally called logs; if they are cut to a specific length, called bolts. The term "log" is informally used in
English 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), 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 from ...
), 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
phloem. 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 of the trunk.
* Directly inside of the cambium is the sapwood, or the 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 from ...
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 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 tree
File:דקל תמר מצוי חתך גזע דמוי עץ (3).jpg, Trunk section from a palm tree (the date palm, '' Phoenix dactylifera'').
File:A ponderosa trunk.jpg,
See also
*
Bark
Bark may refer to:
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Places
* Bark, Germany
* Bark, Warmian-Masurian Voivodeship, Poland
Arts, e ...
*
Basal area
Basal area is the cross-sectional area of trees at breast height (1.3m or 4.5 ft above ground). It is a common way to describe stand density. In forest management, basal area usually refers to merchantable timber and is given on a per hectar ...
*
Diameter at breast height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements.
Tree trunks are measured at the height of an adult's breast, ...
*
Log (disambiguation)
Log most often refers to:
* Trunk (botany), the stem and main wooden axis of a tree, called logs when cut
** Logging, cutting down trees for logs
** Firewood, logs used for fuel
** Lumber or timber, converted from wood logs
* Logarithm, in mathem ...
*
Tree measurement
Trees have a wide variety of sizes and shapes and growth habits. Specimens may grow as individual trunks, multitrunk masses, coppices, clonal colonies, or even more exotic tree complexes. Most champion tree programs focus finding and measuring the ...
*
Tree volume measurement Tree volume is one of many parameters that are measured to document the size of individual trees. Tree volume measurements serve a variety of purposes, some economic, some scientific, and some for sporting competitions. Measurements may include jus ...
References
External links
*
Plant morphology
de:Baum#Aufbau des Baumstammes
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