Oak

An oak is a tree or shrub in the genus Quercus (/ˈkwɜːrkəs/;Latin "oak tree") of the beech family, Fagaceae. There are approximately 600 extant species of oaks. The common name "oak" may also appear in the names of species in related genera, notably Lithocarpus. The genus is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes in the Americas, Asia, Europe, and North Africa. North America contains the largest number of oak species, with approximately 90 occurring in the United States. Mexico has 160 species, of which 109 are endemic. The second greatest center of oak diversity is China, which contains approximately 100 species.

Oaks have spirally arranged leaves, with lobate margins in many species; some have serrated leaves or entire leaves with smooth margins. Many deciduous species are marcescent, not dropping dead leaves until spring. In spring, a single oak tree produces both male flowers (in the form of catkins) and small female flowers. The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6–18 months to mature, depending on species. The live oaks are distinguished for being evergreen, but are not actually a distinct group and instead are dispersed across the genus.

Oak (RTD)

Oak is an RTD light rail station in Lakewood, Colorado, United States. The station is part of the new W Line which was built as part of the FasTracks expansion. It opened in April, 2013 and is operated by the Regional Transportation District.

References

Oak (CTA station)

Oak was a station on the Chicago Transit Authority's North Side Main Line, which is now part of the Brown Line. The station was located at 319 W. Oak Street in the Near North Side neighborhood of Chicago. Oak was situated south of Division, which closed at the same time as Oak, and north of Chicago. Oak opened in 1906 and closed on August 1, 1949, along with 22 other stations as part of a CTA service revision.

References

Oak (disambiguation)

An oak is a tree or shrub in the genus Quercus in the plant family Fagaceae.

Oak or OAK may also refer to:

Plants

People

Places

Tree (Johnny Duhan album)

Tree is an album by Irish folk singer Johnny Duhan.

Track listing

External links

Tree (disambiguation)

A tree is a perennial woody plant.

Tree or trees may also refer to:

Information representation

Mathematics

Computing

Tree (data structure)

In computer science, a tree is a widely used abstract data type (ADT)--or data structure implementing this ADT--that simulates a hierarchical tree structure, with a root value and subtrees of children with a parent node, represented as a set of linked nodes.

A tree data structure can be defined recursively (locally) as a collection of nodes (starting at a root node), where each node is a data structure consisting of a value, together with a list of references to nodes (the "children"), with the constraints that no reference is duplicated, and none points to the root.

Alternatively, a tree can be defined abstractly as a whole (globally) as an ordered tree, with a value assigned to each node. Both these perspectives are useful: while a tree can be analyzed mathematically as a whole, when actually represented as a data structure it is usually represented and worked with separately by node (rather than as a list of nodes and an adjacency list of edges between nodes, as one may represent a digraph, for instance). For example, looking at a tree as a whole, one can talk about "the parent node" of a given node, but in general as a data structure a given node only contains the list of its children, but does not contain a reference to its parent (if any).