Oaks of America
Red oak of America, Quercus rubra
Pin Oak Etymology: the red Oak owes its name to the ruddy shade of its wood.
Height: 20-30 m.
Origin: the East of North America. Introduced into Europe from 1724.
Habitat: the red oak prefers clay soils. Species of full light, it does not tolerate shade. Species of full light, the red oak does not tolerate shade.
Hardiness: Zone 7 (it supports cold until -17 ° or - 4°F).
Lifespan: 200 years or even 500 years in good conditions.
Rate of Growth: moderately fast.
Shape: pyramidal, symmetrical
Bark: grey and smooth.
Deciduous foliage. Leaves from 12 to 22 cm long, cut up in seven or nine lobes. Leaves are broader, bigger and less serrated, than those of the Pin Oak. Dull yellowish-green on top and a paler underneath. Beautiful purple color in the fall.
Flowers: the male flowers are grouped in long catkins from 5 to 7 centimetres in April-May. The female flowers are grouped by two, small (2 mm), ovoid, red and stalked.
Fruits: glandes reddish-browns-red which mature in the course of the second year. About 2 cm long, they are fitted tightly round in a very scaly flat and broad cupule recuperating only the base of the glans.
Use: alignment tree in city because undemanding and it resists well pollution. It was also planted in forest because it grows fast. Its wood, heavy, close-grained (less than the European oaks however), of colour ruddy reddish-brown, is used for carpentry, cooperage, as well as in joinery and in cabinetmaking.
Pin Oak, Quercus palustris
Origin: East of the United States of America and of Canada.
Habitat: the Pin oak grows very well in badly drained fields but it does not demand - as its name could let assume - humid fields. On the contrary, this oak contents itself with relatively dry sands and it cannot grow where some water stagnates during the biggest part of the season of growth. It appreciates clay soils and does not support limestones. Species of full light, it does not tolerate shade.
Hardiness: zone 7 (it supports cold until -17 °C or 1° F ).
Lifespan: 120 years.
Rate of Growth: fast.
Height: 15-20 m.
Shape: pyramidal, symmetrical
Bark: grey and fine to the young oak, covered of furrows rather shallow and crests to the mature tree.
Deciduous foliage. Leaves broad and spreading, cut up in five or seven lobes by broad indentations in the form of U. Dark green colour polished up in the paler back. Nice crimson colouring in autumn. Late fall of leaves.
Flowers: the male flowers are grouped in long catkins from 5 to 7 centimetres in April. It is one of the first oaks to be decorated with flowers.
Fruits: small, blackish glandes, which mature in the course of the second year. About 1 cm long, they are fitted tightly round in a flat cupule, almost sessile.
Use: alignment tree in city because undemanding.
In autumn, the leaves of the oaks of America take colour with bright red, before turning to the brown, and falling, while the European oaks, pass from green to brown, and extend their shades by staying on trees in winter.
Oak with big fruits, Quercus macrocarpa
Mossycup oak, Bur oak (or Burr oak), Northern overcup oak
Etymology: "macrocarpa" means "in big fruits", allusion to the large glandes, bigger than on other oaks.
Origin: the East of North America, until 1000 m of altitude. Introduced into Europe in 1795;
Habitat: the Bur Oak prefers the loamy fields but it supports any soil type, even calcareous. It tolerates seasonal inundation, and drought. It tolerates shade moderately.
Hardiness: zone 4 (it supports cold until -35 °C or -31 °F). It is more hardy than the European oaks.
Lifespan: until 300 years in its original area.
Rate of Growth: slow.
Height: 30 m in its original area, 20 m in Europe.
Shape: broad crown. Its branches, which spread out in the horizontal, are huge.
Right, short, massive trunk from 0,6 to 1,2 m of diameter.
Bark: grey yellowish, bright, becoming cracked, harsh and hazel.
Deciduous foliage. Leaves cut up in deep lobes, 5 - 9 lobes, with strangling in the middle of the blade, of 10-15 cm long on 5-13 cm broad. Colour glossy green over, grayish tomentose on the underside. Rounded off apex. 4-5 pairs of secondary ribs. Short 1,5-2,5 cm petiole.
Flowers in June.
Fruit: broad and oval acorn, pubescent in the apex, from 2,5 to 5 cm long, on a strong 1-2 cm peduncle; deep hirsute cupule (locking the half up or more of the acorn), purple, of 2 cm in diameter. Ripe in 1 year.