Picea glauca

The white spruce of the South Dakotan Black Hills differs enough from its relatives that it is usually given its own varietal name. The cones are shorter, the needles a beautiful blue-grey, and the whole habit of the tree is tight and extremely attractive, which is why it is used in America as a Christmas tree and a garden ornamental.

Because this local variety could also be suitable for small gardens in Finland, a large batch of seeds was ordered in 1993 from seed collector Dean Swift. The collection was made in the Black Hills National Forest at between 1200-1500m elevation, where the climate is very cold but rather more continental than in Finland. The resulting trees have been growing since the year 2000 in a small stand in the western part of the Arboretum. After some early problems they have developed into densely beautiful young trees with bluish needles. It seems that the Black Hills spruce, adapted to a continental climate, is best suited to the eastern parts of Finland. To date, their northern hardiness limit is undefined.

The background of the Alberta spruce is a source of some disagreement. It is considered a south-western form of the white spruce (P. glauca), or perhaps as an intermediate form of a hybrid involving the Engelmann (P. engelmannii) and white spruces, which is what it undoubtedly looks like. The needles are longer than those of the typical white spruce, and the stems of the new growth are hairy, like the Engelmann.

At Mustila, a large stand of Alberta spruce grew for many years in the western part of the Arboretum, near the seasonal greenhouse, Näppäri. Their seed provenance was Crow’s Nest Pass in the Canadian province of Alberta, which is rather continental compared with Mustila’s climate. Like many of the Arboretum’s other exotic spruce plantings, with increasing age this stand has also suffered major insect damage. Currently there is only a small group of trees left. The same provenance has been used in the Finnish Forest Research Institute’s various test plantations, but fairly good results have been obtained only at Punkaharju.

In the year 2000 a small new stand of Alberta spruce, of Kirkup Creek, B.C., provenance, was planted in the spruce collection at Näppäri. Trees of this provenance have generally grown well at Mustila, and the development of these plantings is being followed with interest.

The range of the white spruce covers the whole of the northern parts of North America, forming the tree-line together with black spruce (P. mariana) and tamarack (Larix laricina), aka eastern larch, American larch etc. It grows well on drier soils and on rich moraine soils. For paper and sawn timber it is one of the major species in the US, and THE major species in Canada. The crown resembles that of the Norway spruce but is denser and bluish in colour. The needles of some origins carry a strong scent.

There are many varied forms and colours of the white spruce. One of the most familiar forms is the pillar-like close-branched conical Picea glauca ‘Conica’, which needs protection in Finnish latitudes from severe frosts and winter sunlight to grow successfully.

In Mustila plantations dating from the early 1900s several different seed sources have been tried, from Ontario, Minnesota, Quebec. They are all smaller and slower-growing than local Norway spruce (P. abies), but have not suffered frost damage. However, they have aged faster than in their natural habitat. Only a few poor examples of the original plantings are to be found today, on Pohjoisrinne, or North Slope and in Lepistö. The latter are of the western form, var. albertiana, which in fact is an intermediate form between white spruce and Engelmann spruce.

In 2000, new plantings of both white spruce and the intermediate form were made in the spruce collection in the west part of the Arboretum. These plantings consisted of the best thriving provenances from central British Columbia.