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Alnus japonica Sieb. & Zucc.

Modern name

Alnus japonica (Thunb.) Steud.

A pyramidal tree from 60 to 80 ft high; young shoots glabrous, or downy towards the base; buds stalked. Leaves lanceolate to narrowly ovate or oval, tapered at both ends, usually more slenderly at the apex; 2 to 5 in. long, 34 to 2 in. wide, finely toothed, glabrous, dark glossy green; stalks downy, 12 to 1 in. long. Male catkins opening in February or March, according to the warmth of the season, and produced in a terminal cluster of four to eight; each catkin erect, 2 to 312 in. long. Fruits oval, 34 in. long.

Native of Japan and continental N.E. Asia, the true date of whoseintroduction is not recorded. Plants obtained from Lee’s nursery had already reached the fruiting state at Kew in 1880. It is considered to have some relationship with the North American A. maritima, and has been regarded as a variety of it, but in the field it is quite distinct. It grows more than twice as high, has narrower, long-pointed leaves; and more than all, its habit of flowering in spring distinguishes it.

A. × spaethii Callier – A hybrid between A., japonica and A. subcordata, sent out by Späth of Berlin in 1908. Unfolding leaves, violet-purple.

From the Supplement (Vol. V)

There is an example of this species in the Edinburgh Botanic Garden, measuring 62 × 9 ft (1985).

† A. mayrii Callier – This is closely allied to A. japonica, but with relatively broader leaves less tapered at the apex, and is thought to be a natural hybrid between that species and A. hirsuta. There is an example at Kew by the lake.

A. × spaethii – As noted briefly in the reprint, this hybrid was highly rated in trials held at Boskoop in Holland (Dendroflora, No. 9 (1972), pp. 7-8). It was reported to be good as a park and street tree and, at least in Holland, capable of attaining a height of about 50 ft in fifteen years. The two examples at Kew by the lake were received from Späth in 1909.



Other species in the genus