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Common ash (*Fraxinus excelsior*), a deciduous broad-leaved (angiosperm) 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 are usable as lumber or plants above a specified height. In wider definitions, the taller palms, tree ferns, bananas, and bamboos are also trees.

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 reaching several thousand years old. Trees evolved around 370 million years ago, and it is estimated that there are around three trillion mature trees in the world currently.

A tree typically has many secondary branches supported clear of the ground by the trunk, which typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees the trunk is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development.

Trees usually reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms, bananas, and bamboos also produce seeds, but tree ferns produce spores instead.

Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In much of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture. Because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, and they play a role in many of the world's mythologies. (Full article...)

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At Villa Durazzo-Pallavicini

Banksia serrata, commonly known as the saw banksia, the old man banksia, the saw-tooth banksia or the red honeysuckle and as wiriyagan by the Cadigal people, is a species of woody shrub or tree of the genus Banksia, in the family Proteaceae. Native to the east coast of Australia, it is found from Queensland to Victoria with outlying populations on Tasmania and Flinders Island. Commonly growing as a gnarled tree up to 16 m (50 ft) in height, it can be much smaller in more exposed areas. This Banksia species has wrinkled grey bark, shiny dark green serrated leaves and large yellow or greyish-yellow flower spikes appearing over summer. The flower spikes, or inflorescences, turn grey as they age and pollinated flowers develop into large, grey, woody seed pods called follicles.

B. serrata is one of the four original Banksia species collected by Sir Joseph Banks in 1770, and one of four species published in 1782 as part of Carolus Linnaeus the Younger's original description of the genus. There are no recognised varieties, although it is closely related to Banksia aemula. Throughout its range, it grows exclusively in sandy soil, and is usually the dominant plant in scrubland or low woodland. B. serrata is pollinated by and provides food for a wide array of vertebrate and invertebrate animals in the autumn and winter months, and is an important source of food for honeyeaters. It is a common plant of parks and gardens. (Full article...)

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... that fossil leaves almost identical to those of the Australian rainforest tree Orites excelsus (pictured) have been found in New Zealand?
... that more than 8000 trees were planted in Backmuir Wood to celebrate the 2000 millennium?
... that the name of the newly defined genus of macadamia-like trees, Lasjia, is derived from the initials of Lawrence Alexander Sidney Johnson?
... that at St Athan, a wild fig tree grew out of the cement of the East Orchard chapel walls?
... that in the churchyard of St Mary and St Peter's Church in Wilmington, East Sussex, there is a 1,600-year-old, 23-foot (7 m) wide yew tree?
... that Christopher Werner made a lifelike South Carolina Palmetto tree out of iron, copper, and brass?
... that seed from an endangered Chrysophyllum imperiale tree planted in Royal Botanic Gardens, Sydney in 1868 by Prince Alfred has been sent to its native Brazil to aid in recovering the species there?

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The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world.

A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' Food and Agriculture Organization (FAO) defines a forest as, "Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able to reach these thresholds in situ. It does not include land that is predominantly under agricultural or urban use." Using this definition, Global Forest Resources Assessment 2020 (FRA 2020) found that forests covered 4.06 billion hectares (10.0 billion acres; 40.6 million square kilometres; 15.7 million square miles), or approximately 31 percent of the world's land area in 2020.

Forests are the largest terrestrial ecosystems of Earth by area, and are found around the globe. 45 percent of forest land is in the tropical latitudes. The next largest share of forests are found in subarctic climates, followed by temperate, and subtropical zones. (Full article...)

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General images

The following are images from various tree-related articles on Wikipedia.

Image 1World production of selected forest products (from Forest)
Image 2Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
Image 3A young red pine (Pinus resinosa) with spread of roots visible, as a result of soil erosion (from Tree)
Image 4Share of forest area in total land area, top countries (2021) (from Forest)
Image 5The General Sherman Tree, thought to be the world's largest by volume (from Tree)
Image 6Selling firewood at a market (from Tree)
Image 7Dormant Magnolia bud (from Tree)
Image 8Roof trusses made from softwood (from Tree)
Image 9Informal upright style of bonsai on a juniper tree (from Tree)
Image 10Diagram of secondary growth in a eudicot or coniferous tree showing idealised vertical and horizontal sections. A new layer of wood is added in each growing season, thickening the stem, existing branches and roots. (from Tree)
Image 11Cracked thorny skin of a Aesculus tree seed (from Tree)
Image 12Common ash (Fraxinus excelsior), a deciduous broad-leaved (angiosperm) tree (from Tree)
Image 13Yggdrasil, the World Ash of Norse mythology (from Tree)
Image 14Conifers in the Swabian alps (from Tree)
Image 15A section of yew (Taxus baccata) showing 27 annual growth rings, pale sapwood and dark heartwood (from Tree)
Image 16Neem tree at Sant Nenuram Ashram (from Trees of Pakistan)
Image 17Proportion and distribution of global forest area by climatic domain, 2020 (from Forest)
Image 18Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
Image 19Latvian Pine Forest in Ķegums Municipality (from Forest)
Image 20Olive trees in Pakistan (from Trees of Pakistan)
Image 21Even, dense old-growth stand of beech trees (Fagus sylvatica) prepared to be regenerated by their saplings in the understory, in the Brussels part of the Sonian Forest. (from Forest)
Image 22Buds, leaves and reproductive structures of white fir (Abies alba) (from Tree)
Image 23Forest in the Scottish Highlands (from Forest)
Image 24Fraxinus excelsior (from List of trees of Great Britain and Ireland)
Image 25Proportion of forest in protected areas, by region, 2020 (from Forest)
Image 26Form, leaves and reproductive structures of queen sago (Cycas circinalis) (from Tree)
Image 27The Daintree Rainforest (from Tree)
Image 28Recently stripped cork oak (Quercus suber) (from Tree)
Image 29Trees in art: Weeping Willow, Claude Monet, 1918 (from Tree)
Image 30Burned forest on Thasos (from Forest)
Image 31Northern beech (Fagus sylvatica) trunk in autumn (from Tree)
Image 32Alleé of London plane trees (Platanus × acerifolia) in garden (from Tree)
Image 33European larch (Larix decidua), a coniferous tree which is also deciduous (from Tree)
Image 34People trees, by Pooktre (from Tree)
Image 35Share of land that is covered by forest (from Forest)
Image 36Since the 13th century, the Niepołomice Forest in Poland has had special use and protection. In this view from space, different coloration can indicate different functions. (from Forest)
Image 37Rowan tree in Wicklow, Ireland (from List of trees of Great Britain and Ireland)
Image 38Alnus glutinosa (from List of trees of Great Britain and Ireland)
Image 39Buttress roots of the kapok tree (Ceiba pentandra) (from Tree)
Image 40Buds, leaves, flowers and fruit of oak (Quercus robur) (from Tree)
Image 41Lepidodendron, an extinct lycophyte tree (from Tree)
Image 42Malus sylvestris (from List of trees of Great Britain and Ireland)
Image 43Redwood tree in northern California redwood forest, where many redwood trees are managed for preservation and longevity, rather than being harvested for wood production (from Forest)
Image 44Temperate rainforest in Tasmania's Hellyer Gorge (from Forest)
Image 45Garibaldi Provincial Park, British Columbia (from Forest)
Image 46Wind dispersed seed of elm (Ulmus), ash (Fraxinus) and maple (Acer) (from Tree)
Image 47Broadleaf forest in Bhutan (from Forest)
Image 48The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
Image 49Palms and cycads as they might have appeared in the middle Tertiary (from Tree)
Image 50Sugar maple (Acer saccharum) tapped to collect sap for maple syrup (from Tree)
Image 51A forest near Vinitsa, North Macedonia (from Forest)
Image 52Latex collecting from a rubber tree (Hevea brasiliensis) (from Tree)
Image 534000 years old Cypress of Abarqu is the oldest tree in Iran and the second oldest tree in the world. (from List of trees of Iran)
Image 54Priest River winding through Whitetail Butte with lots of forestry to the east—these lot patterns have existed since the mid-19th century. The white patches reflect areas with younger, smaller trees, where winter snow cover shows up brightly to the astronauts. Dark green-brown squares are parcels (from Forest)