Red oak

The genus Quercus (oak) contains about 600 species, some of which are listed here.

For the taxonomic status of the oaks see The Plant List

The white oaks (synonym sect. Lepidobalanus or Leucobalanus). Europe, Asia, north Africa, North America. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless.

Europe, Asia, north Africa. Styles long; acorns mature in 6 months, bitter, inside of acorn shell hairless (closely related to sect. Quercus and sometimes included in it).

Europe, Asia, north Africa. Styles long; acorns mature in 18 months, very bitter, inside of acorn shell hairless or slightly hairy.

The intermediate oaks. Southwest USA & northwest Mexico. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly.

The red oaks (synonym sect. Erythrobalanus). North, Central & South America. Styles long, acorns mature in 18 months(in most species), very bitter, inside of acorn shell woolly.

The ring-cupped oaks (synonym genus Cyclobalanopsis). Eastern and southeastern Asia. They are distinct from subgenus Quercus in that they have acorns with distinctive cups bearing concrescent rings of scales; they commonly also have densely clustered acorns, though this does not apply to all of the species. About 150 species.

# Species with evergreen foliage ("live oaks") are tagged #. Note that the change from deciduous to evergreen character (or vice versa) has evolved on numerous occasions in Quercus, and does not necessarily indicate that the species concerned are closely related.

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