Glen's spruce

Synonyms: Sakhalin spruce

Glen's spruce – a species of evergreen trees of the genus Spruce (family Pinaceae). The species was named after its discoverer P.P. Glen, a well-known botanist, geographer, traveler, plant taxonomist, hydrographer, and also an explorer of Sakhalin and the Amur region. It is considered a rare species and is included in the Red Book of the Sakhalin Region of the Russian Federation. It was introduced to Western Europe in 1877. In cultivation since 1914.

The range is distributed on the island of Hokkaido (Japan). It also grows on Mt. Hayachine, Kitakami, in the northern part of Honshu, as well as in the south of Sakhalin (Russia) and in the southern Kuril Islands, where it occurs in cold lowlands with excessive soil moisture on a stony subsoil, rising to elevations of 0-1600 m above sea level.

It is a tall tree 62-73 m in height. In youth (up to 10-15 years) the plant is slow-growing (25-30 cm per year), later the growth rate increases. Annual increment 50 cm in height and 15 cm in width. Crown dense, conical. Bark of young trees smooth, of old ones scaly, plated, chocolate-brown in color (a species characteristic). Young shoots are burgundy or orange, pubescent on the petioles (up to 1 mm in length) and along the grooves. Buds ovate-conical, 3-7 mm long and 5 mm wide, slightly resinous, reddish-brown. Bud scales trigonous or triangular, with a long awl-shaped apex.

Needles four-sided, slightly curved, short, 10 mm long and 2.5 mm wide, blunt at the tip, glaucous-green, releasing a strong characteristic odor when crushed.

Blooms in spring. Pollination is not annual and not abundant. Female cones are purple-red, turning brown at maturity, elongated, glossy, 3-5 cm long and 2 cm in diameter. Scales are spreading. Seed scales inverse-ovate in shape, narrowed toward the base, delicately pubescent outside, apex triangular-rounded, sometimes wavy-curved at the edges. Seeds inverse-ovate, small. Wing 1.5-2 times longer than the seed. Begins bearing seeds at 25-30 years. Mass of 1000 seeds is 3.3 g.

Hybrids: forms a hybrid Picea ×notha with the Ayan spruce (Picea jezoensis).

Hardiness zone: 4a (-35°)

Location: prefers fresh and fairly moist soil. Can tolerate temporary flooding of the root collar. Not demanding regarding soil fertility. Shade-tolerant similar to the common spruce. Susceptible to windthrow. Tolerance to urban conditions is low. Prefers sites with higher air humidity, preferably near artificial or natural water bodies.

Planting: Soil mix: turf and leaf soil, peat, sand in the ratio 2:2:1:1. Drainage made from crushed brick, layer 15-20 cm. Planting depth: 50-70 cm. Root collar at ground level.

Care: after planting you can apply 100-150 g of nitroammophoska. During dry periods it is recommended to water at least once a week with 10-12 L per plant. Loosening is carried out to a depth of 5-6 cm, while peat is not removed but mixed with the soil. Young seedlings need to be covered with fir branches for the winter.

Pruning: sanitary pruning is applied.

Diseases: schütte, snow schütte, fusariosis, stem and root rot, bark necrosis, ulcerous (canker) disease, cone rust, spruce vertun. Suffers less from spring burns than other varieties of the Canadian spruce.

Pests: spruce leaf roller, spider mite, Sitkhinskaya spruce aphid.

Propagation: seed germination 60-80%. Seeds germinate without pre-sowing treatment, but cold stratification (2 to 8 weeks) or soaking in water (18 to 22 hours) increases germination percentage. Also propagated by cuttings.

Uses: rarely used in landscape design. Looks good in solitary and group plantings in open-view parks and gardens near water bodies. Can be used as a conifer that grows better than other species on boggy sites. Indispensable for creating forest parks.

Companions: pairs well with deciduous trees, especially with Gmelin's larch.