Quercus

The leaves of the red oak are larger, and the lobes more pointed, than those of the native oak (Quercus robur). Their strong red autumn colour dominates the landscape in their native range, the eastern parts of North America, but in Finland they aren’t usually as strongly coloured, usually a brownish red.

The red oak has a broad range in North America. In Finland, the climate is very demanding so seed provenance is important. The old red oak wood at Mustila has grown well but hardens off rather late, so is probably not of an especially northern provenance. New plantings at the bottom edge of Etelärinne (Southern Slope) are from a variety of acorns gathered by Mustila expeditions in 1993 and 1996. A little surprisingly, the earliest and best autumn colour develops on trees whose provenance is the northern part of Wisconsin, USA.

The acorn of the red oak has been chosen as the emblem of the ”Friends of Arboretum Mustila” society. The red oak is one of the basic trees of the Arboretum collection and the acorn symbolises the birth of a new tree, or even a whole forest.

The oak is perhaps the most highly valued of all European trees. The strength of its timber, its size and resistance to decay (for example in ships, furniture and wine barrels) have been contributing factors. Trees can live for over a thousand years and large old oaks are important landmarks. Old oaks are rarely seen in Finland because for hundreds of years oak forests have been destroyed to make way for farming, and for their valuable timber.

But in suitable areas in the south of Finland the oak makes a beautiful landscape tree, as well as offering a viable alternative to the species usually used for timber production. However, growing oaks to logging stature demands special skill. Several different methods have been tried at Mustila. The best stand has been grown from acorns obtained from Sangaste Manor in Estonia in the 1920s. This provenance produces fast-growing straight trees which rapidly achieve logging size. Acorns are collected here annually for widespread production.

The English oak often suffers leaf damage in late spring frosts. With bigger trees the damage is negligible because they grow new foliage in a few weeks, but small seedlings planted in areas susceptible to late frosts are another matter: they very often tend to remain shrubby in habit. Other threats to young oaks are rodents and deer.

Mongolian oak (Q. mongolica) grows over a large range throughout East Asia and several subspecies and forms have been described, some of them even awarded the status of separate species. The most successful of these in Finland has been the maritime Japanese subspecies called mizu-nara (Q. mongolica subsp. crispula) because it is hardier in the Finnish type of climate, which is unsettled and changeable. The northern provenances from Hokkaido and Sakhalin Island are also hardy to severe frosts. They have been planted in the Japan area on Pohjoisrinne (Northern Slope), for example.

Mizu-nara grows naturally on all of Japan’s main islands and also on Sakhalin and the Kuriles to the north. Compared to the continental Mongolian oaks, the Japanese subspecies is better in several ways: it grows faster, with a straight trunk, and starts growing later in the spring so late frosts are less likely to cause damage to new growth. Abundant acorns are produced while the trees are still quite young. The foliage takes on beautiful red or golden brown autumn colours before the other hardy oaks, which shows that Mizu-nara is well adapted to severe winters.