Amur cork tree

Synonyms: Phellodendron amurense, Amur cork-tree

Amur cork tree (Phellodendron amurense Rupr.) ( ) – a species of dioecious plants of the genus Phellodendron ( ) in the family Rutaceae. The species was first described by the botanist F.I. Ruprecht in 1857 in his work Bull. Cl. Phys.-Math. Acad. Imp. Sci. Saint-Pétersbourg 15:353. In cultivation since 1885. It is a relict plant that grew before the glaciation.

The range extends across the Far East, in the forests of Manchuria, Khabarovsk, Priamurye, Primorye, in China, Korea, Taiwan, Sakhalin, the Kuril Islands, and in Japan. It occurs in valley mixed broad-leaved forests, less often on mountain slopes and hillsides, at elevations of 500-700 m above sea level, where it appears as an admixture in coniferous-broadleaf and secondary forests.

It is a dioecious deciduous tree 25-28 m tall, the trunk reaching 90-120 cm in diameter, fast-growing, living up to 300 years. In the forest the crown is held high; in open sites it is pyramidal, airy, set low on the trunk, 10-12 m in diameter. The bark is up to 7 cm thick, ash-gray in color, very decorative, consisting of two layers: a cork layer (up to 5 cm thick) and an inner phloem layer, sharply demarcated from the brownish heartwood, with a characteristic odor; in young trees the bark is silvery-gray, velvety, soft, longitudinally wrinkled and deeply furrowed. Young shoots are gray and smooth.

Leaves are imparipinnate, petiolated, arranged alternately, in the upper part opposite, in shape resembling ash leaves ( ). Leaflets are lanceolate, with a finely crenate margin, and have an unpleasant odor. Leaves unfold later than those of other deciduous species – in late May to early June. Flowers in June–July.

Begins to flower at 18-20 years of age. Flowering can be observed in June — early July, for about 10 days. Flowers are small, up to 0.8 cm in diameter, inconspicuous, yellowish-green, regular, five-parted, unisexual, borne in paniculate racemes up to 12 cm long. Pollinated by insects.

Fruits are spherical inedible drupes, up to 1 cm in diameter, glossy, black, with a sharp characteristic odor. Stones usually number 5. It fruits annually, producing up to 10 kg of fruit.

Varieties: Phellodendron amurense var. wilsonii

Hardiness zone: 3a (-40°C).

Location: warmth-loving, light-loving. Prefers loamy soil, does not tolerate sandy soil.

Planting: planting hole size 0.5-0.65 m; fill it with a mixture of garden soil, turf soil, humus and sand in the ratio 2:2:2:1. Planting is carried out in spring or autumn (no later than mid-October; if later, it is preferable to heel the plant in at an angle until spring). Ideal age for transplanting is 1-2 years.

Watering: after planting the plant requires frequent watering – the soil should be kept moist. Subsequently water only during dry periods.

Care: fertilizers and feedings are applied in the first half of summer; well-rotted organic matter and a complete mineral fertilizer scattered under the crown followed by digging are appropriate.

Pruning: pruning must be carried out very carefully – trees are pruned in spring and wounds are sealed with tree wound dressing.

Pests and diseases: practically unaffected.

Propagation: readily propagated by stratified seeds. Can also be propagated by cuttings or by root suckers.

Uses: ideally suited for creating avenues in parks and large gardens, looks good as a specimen on a lawn. Combines well with low-growing shrubs: thuja, juniper, barberry. Looks impressive with birch, spruce, oak and maple.