Quercus delgadoana

Quercus delgadoana is an endangered species of oak in the family Fagaceae, found in eastern Mexico. It was originally misidentified as other members of the genus Quercus, but was determined as a new species in 2011.

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Individuals of this species are oak trees that grow up to 25 metres (82 feet) tall and have trunks 0.5–1.2 m (1+1⁄2–4 ft) in diameter. These oaks are often among the tallest trees in the wet montane forests. They are characterized by their 1.8–4-millimetre (1⁄16–5⁄32-inch) thick branchlets and lance-shaped leaves with revolute margins. They bear acorns as fruits and have pistillate flowers on a short 1.5–8 mm (1⁄16–5⁄16 in) stalk, which have 1 or 2 distal flowers. Quercus delgadoana was determined as a new species because, unlike Q. eugeniifolia with fruit with annual maturation, this species has fruit with biennial maturation. In addition, this new species can be distinguished from other similar species such as Q. laurina and Q. affinis because it has more secondary veins, a revolute blade margin, and an adaxial leaf surface without stellate trichomes. The flowers may develop in March, but only pistillate flowers can be observed; fruits with biennial maturation can be found in October and November. The fruits take two years to mature and are presented on the terminal twigs.