Larix

The history of larch plantings for timber outside their natural range is a long one. This has lead to the realisation that closely related larch species, when planted close together, can hybridise. Hybrids have also been produced and planted deliberately, often being faster-growing than their parent species. This characteristic is known as heterosis, or hybrid-vigour. The best-known hybrid world-wide is that between the Japanese and European larches (Larix x marschlinsii), known as “Henry’s larch” in Finnish, but Dunkeld or simply Hybrid larch in English.

There are two hybrid larch stands at Mustila. Along the edge of the field at the bottom edge of the North Slope there are hybrids of the Japanese larch (L. kaempferi), and at the Lepistö (Alder Wood) bend there are hybrids of the Kurile larch (Larix gmelinii var. japonica). The trees here have all been selected while young for their fast growth. The bluish needles of the Japanese larch have been inherited by their hybrids, while the Kurile hybrids exhibit the wide-spreading branches of the parent species.

The Siberian larch is native to the areas on both sides of the Ural Mountains. It is spreading west and the nearest natural forests can be found on the eastern shore of Lake Onega (Ääninen in Finnish) in Russia. The species grew in Finland before the last Ice Age and thrives now throughout the country. The straight trunk and fine branches make it an ideal forest tree. The crown is narrowly conical. The young branches are stiffer than those of other larches and seldom droop. In autumn it is the first larch to change colour.

Siberian larch has been grown in Finland since the 1700s. The oldest known plantation is the Raivola (Lintula) stand on the Karelian Isthmus, which is considered the best provenance for seed for Finnish conditions. The oldest parts of the Raivola stand were established in the 1700s using seed from Arkangel, with later plantings from seed originating west of the Urals. The Raivola larches are ecologically adaptable and have been grown successfully throughout Scandinavia, including Iceland.

A Siberian larch stand was planted at the north-eastern edge of Arboretum Mustila using Raivola seed in 1928. At Lepistö there is also another stand, whose seed provenance is Tomsk in western Siberia; this stand has grown less well, for ecological reasons.

Olga Bay larch is native to North Korea and neighbouring areas where the climate is similar to Finland’s. Fast-growing, hardy, and beautiful, it grows well in southern and central Finland. Unfortunately, it has so far been planted almost solely in scientific collections. Significant characteristics in identifying the species are the slightly upward-growing branches, very short needles and the cones, which are shiny red before ripening.

Mustila has a small plantation of Olga Bay larch on the west side of Etelärinne (Southern Slope), dating from about 1910. The provenance is unknown. A. F. Tigerstedt had noticed their rapid growth and early autumn coloration in the nursery stage, the latter an indicator of hardiness. Now over a century old, they are still beautiful, like slender versions of the European larch (L. decidua).