Trunk (botany)

Trunks are the <a href="/facts/Plant_stem/QlQWSzV4">stems</a> of <a href="/facts/Woody_plant/xXCI9yys">woody plants</a> and the main structural element of <a href="/facts/Tree/HVVn3srN">trees</a>. The woody part of the trunk consists of dead but structurally significant heartwood and living sapwood, which is used for nutrient storage and transport. Separating the wood from the bark is the <a href="/facts/Vascular_cambium/y9JG1eEu">cambium</a>, from which trunks grow in diameter. Bark is divided between the living inner bark (the <a href="/facts/Phloem/I34nY0gF">phloem</a>), which transports sugars, and the outer bark, which is a dead protective layer.
The precise <a href="/facts/Cell_(biology)/bLM9UQvy">cellular</a> makeup of these components differs between non-flowering plants (<a href="/facts/Gymnosperm/lzcpfbUK">gymnosperms</a>) and flowering plants (<a href="/facts/Flowering_plant/E5eGYIvY">angiosperms</a>). A variety of specialised cells facilitate the storage of <a href="/facts/Carbohydrate/Geuuzxsf">carbohydrates</a>, water, <a href="/facts/Mineral/LkUFbNmv">minerals</a>, and transport of water, minerals, and <a href="/facts/Hormone/WFnBnINJ">hormones</a> around the plant. Growth is achieved by <a href="/facts/Cell_division/n5MrunWj">division</a> of these cells. Vertical growth is generated from the <a href="/facts/Meristem/YlMKp2W5">apical meristems</a> (stem tips), and horizontal (radial) growth, from the cambium. Growth is controlled by hormones, which send <a href="/facts/Chemical_substance/EWcXU41d">chemical</a> signals for how and when to grow.
Plants have <a href="/facts/Evolution/Hj0qAaBk">evolved</a> to both manage and prevent damage from occurring to trunks. Trunks are structured to resist wind forces, through characteristics such as high <a href="/facts/Strength_(material)/CE77cUcB">strength</a> and <a href="/facts/Stiffness/xlabLkfT">stiffness</a>, as well as oscillation <a href="/facts/Damping/UW3RsjEd">damping</a>, which involves taking energy, and therefore damage (by extension), out of the trunk and into the <a href="/facts/Branch/byMv8JP3">branches</a> and <a href="/facts/Leaf/1m6wCNTg">leaves</a>. If <a href="/facts/Wound/snv0h3Gj">damaged</a>, trunks employ a complex and slow defence mechanism, which starts by creating a barrier to the incoming disease. Eventually, diseased cells are replaced by new, healthy cells, once the threat is contained.
Ecologically, trunks not only support the extensive ecological function of living trees, but also play a large ecological role when the trees eventually die. Dead trunk matter, termed <a href="/facts/Coarse_woody_debris/WsRFK1U0">coarse woody debris</a>, serves many roles including: plant and animal <a href="/facts/Habitat/zo1DN2gA">habitat</a>, <a href="/facts/Nutrient_cycle/S57nuGbQ">nutrient cycling</a>, and the transport and control of <a href="/facts/Soil/5Ddpr3QM">soil</a> and <a href="/facts/Sediment/zsIH1A6U">sediment</a>. Most trees grown outside the tropics can be dated (have their age estimated) by counting their <a href="/facts/Dendrochronology/bXK8Km2M">annual rings</a>. Variations in these rings can provide insights into climate, a field of study called <a href="/facts/Dendroclimatology/Fj7rspg7">dendroclimatology</a>. Trunks have been in continuous use by humans for thousands of years including in construction, medicine, and a myriad of wood-related products. Culturally, trunks are the subject of symbolism, folk belief, ritual, and feature in art of many mediums.

Trunk (botany) open-in-new

Trunk (botany)