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Species: Quercus rubra L.

(Quercus rubra L.)
-> Genus: Quercus -> Family: Fagaceae -> Group: Angiosperms

Habitus

  • tree with the height  of 30 - 40 m, crown broadly oval, spreading, branches thick
  • bark is long smooth light gray and even at an older age only shallowly rectangularly cracked bork
Quercus rubra (Red oak) - bork
Quercus rubra (Red oak) - bork

Buds

  • buds are arranged in a spiral, piled at the end, egg-shaped, pointed, 5 - 8 x 3 - 5 mm in size, sitting
  • the scales are multiple, brown to reddish with a darker edge
Quercus rubra (Red oak)
Quercus rubra (Red oak)
Quercus rubra (Red oak)

Shoots

  • they are direct, longitudinally grooved, green-brown
  • lenticels: small, yellowish
Quercus rubra (Red oak)
Quercus rubra (Red oak)
Quercus rubra (Red oak)

Leaves (assimilation organs)

  • the leaves are simple, pinnately lobed to incised, elongated elliptical, 12 - 22 x 8 - 10 cm in size
  • the incisions are rounded, with 3 - 5 spiny tips on the individual lobes
  • the upper side is dark green, matte, and glabrous
  • the underside is light green, at least hairy in the axils of the veins
  • the petiole is 3 - 5 cm long, glossy
  • the leaves themselves are firm, thin, leathery
  • in autumn, they turn red
Quercus rubra (Red oak) - upper side
Quercus rubra (Red oak) - underside (hairs in the axils of the veins)
Quercus rubra (Red oak) - twig with leaves
Quercus rubra (Red oak) - upper side
Quercus rubra (Red oak) - (+/- pinnately serrated)

Flowers

  • it is a dioecious woody plant, the flowers are of different sexes
  • it blooms relatively late in spring in V – VI

Fruits – seeds

  • the fruit is an oval achene stored in a shallow leathery involucre
  • it is 1.5 - 2.5 x 1.0 - 1.5 cm in size, truncated at the base, and narrowed to a sharp tip at the top
  • it is reddish-brown, slightly silvery and hairy around the top
  • it ripens in September of the second year
Quercus rubra (Red oak)
Quercus rubra (Red oak)
Quercus rubra (Red oak) - acorn
Quercus rubra (Red oak) - acorn
Quercus rubra (Red oak) - fruits (nuts) in the first year

Extension

  • originally widespread in the eastern part of the North American continent
  • it grows at altitudes from 300 to 1,600 m above the sea level
  • it reaches its largest dimensions on glacial moraines and riverbanks with flowing groundwater
  • it was introduced to Europe in 1691

Ecology

  • in its youth, it can tolerate shading
  • in Slovakia, it thrives in wetter soils with a high level of flowing groundwater
  • it is frost-resistant

Significance

  • it is a decorative tree mainly with red-colored leaves in autumn
  • it provides high-quality wood

From history

Quercus rubra (Red oak) - Unsere Waldbäume, Sträucher und Zwergholzgewächse. Heidelberg, Carl Winter`s Universitätsbuchhandlung
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