Trunk (botany) in the context of "Yule log"

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, e.g., including only woody plants with secondary growth, only plants that are usable as lumber, or only plants above a specified height. Wider definitions include taller palms, tree ferns, bananas, and bamboos.

Trees are not a monophyletic taxonomic group but consist of a wide variety of plant species that have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight. The majority of tree species are angiosperms or hardwoods; of the rest, many are gymnosperms or softwoods. Trees tend to be long-lived, some trees reaching several thousand years old. Trees evolved around 400 million years ago, and it is estimated that there are around three trillion mature trees in the world currently.

Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. In forestry, the term logging is sometimes used narrowly to describe the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard. In common usage, however, the term may cover a range of forestry or silviculture activities.

Logging is the beginning of a supply chain that provides raw material for many products societies worldwide use for housing, construction, energy, and consumer paper products. Logging systems are also used to manage forests, reduce the risk of wildfires, and restore ecosystem functions, though their efficiency for these purposes has been challenged.

A tree stump is the remaining portion of a tree trunk and its roots that remain after a tree has been felled or has naturally fallen. The roots often remain largely intact underground.

The cross section of a tree stump shows the annual growth rings that can reveal the tree's age, growth patterns, and environmental conditions during its lifetime. The scientific study of these rings, known as dendrochronology, can reveal historical climate information.

Phytophthora ramorum is the oomycete known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present in Europe. Symptoms include bleeding cankers on the tree's trunk and dieback of the foliage, in many cases leading to the death of the tree.

P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron, Viburnum, and Pieris, causing foliar symptoms known as ramorum dieback or ramorum blight. Such plants can act as a source of inoculum for new infections, with the pathogen producing spores that can be transmitted by rainsplash and rainwater.

Tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tree ferns), Dicksoniaceae, Metaxyaceae, and Cibotiaceae. It is estimated that Cyatheales originated in the early Jurassic, and is the third group of ferns known to have given rise to tree-like forms. The others are the extinct Tempskya of uncertain position, and Osmundales where the extinct Guaireaceae and some members of Osmundaceae also grew into trees. In addition there were the Psaroniaceae including Tietea in the Marattiales, which is the sister group to all the leptosporangiate ferns.

Other tree ferns include Leptopteris and Todea in the family Osmundaceae, which can achieve short trunks under a metre tall. Osmunda regalis is sometimes considered a tree fern. Fern species with short trunks in the genera Blechnum, Cystodium and Sadleria from the order Polypodiales and smaller members of Cyatheales like Calochlaena, Cnemedaria, Culcita, Lophosoria and Thyrsopteris are also considered tree ferns. The species Ctenitis sloanei (Florida tree fern) from Florida, Mexico, Bermuda and the Caribbean is sometimes called a tree fern. Like all ferns, tree ferns reproduce by means of spores formed on the undersides of the fronds.

Cycads /ˈsaɪkædz/—constituting the division Cycadophyta—are seed plants with a stout, woody cylindrical trunk with a crown of large, hard, stiff, evergreen and usually pinnate (feather-shaped) leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. They superficially resemble palms or ferns, but are not closely related to either group. Cycads are gymnosperms. Cycads have specialized pollinators, usually a specific beetle, and more rarely a thrips or a moth.

Both male and female cycads bear cones (strobili) containing their seeds, somewhat resembling conifer cones. Cycads fix nitrogen in association with cyanobacteria living in the plants' roots. Some species are used as narcotics, while in Vanuatu the plant symbolizes peace and appears on the national flag. Cycads all over the world are in decline, with four species on the brink of extinction and seven species each with fewer than 100 plants left in the wild.

The crown of a plant is the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area.

The crown of a woody plant (tree, shrub, liana) is the branches, leaves, and reproductive structures extending from the trunk or main stems.

In woodworking, hewing is the process of converting a log from its rounded natural form into lumber (timber) with more or less flat surfaces using primarily an axe. It is an ancient method, and before the advent of sawmills, it was a standard way of squaring up wooden beams for timber framing. Today it is still used occasionally for that purpose by anyone who has logs, needs beams, and cannot or would prefer not to pay for finished lumber. Thus, homesteaders on frugal budgets, for example, may hew their own lumber rather than buy it.