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Tim Baxter & Hugh A. McAllister (2021)
Baxter, T. & McAllister, H.A. (2021), 'Alnus pendula' from the website Trees and Shrubs Online (treesandshrubsonline.
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Large shrub or tree, 3–8 m; multistemmed. Branchlets dark greyish brown, slender and pendulous, with short-lived silky hairs. Buds with two glabrous, membranous bracts. Leaves deciduous, 4.5–12 × 2.2–4.5 cm, narrowly ovate to broadly lanceolate, upper surface green and not glossy, lower surface pale green, appressed, silky hairs on the veins, 20–26 lateral veins on each side of the midvein, margins doubly serrated, apex long-acuminate; petiole densely pubescent, 0.3–0.8 cm long. Staminate inflorescences catkin-like, 5–12 cm long; pistillate inflorescences in racemes of three to six, pedunculate, ellipsoid, 0.8–1.2 × 0.6–0.8 cm. Cone woody, 1.2–1.6 × 0.8–1.2 cm, bracts 0.3 cm wide. Flowering April to May, fruiting September to October (Japan). Ohwi 1965. Distribution JAPAN: Hokkaido, Honshu – very common in northern Honshu on waste ground and by roadsides (K. Ashburner, pers. comm. 2007); NORTH KOREA; SOUTH KOREA. Habitat Montane forest to 1500 m asl. USDA Hardiness Zone 5–6. Conservation status Not evaluated. Illustration NT134, NT135, NT143. Cross-references B274, K133 (both as A. firma var. multinervis).
This exceptionally attractive green alder is without question more a shrub than a tree, but it could probably be trained into a single-stemmed tree if required. The branches arise from the base and arch outwards, bearing pendulous shoots that carry the narrow, sharply pointed and strongly veined leaves; comparison with leaves of Carpinus is not inappropriate. The effect is extremely elegant, and this would be a beautiful plant for a lakeside. There is a good group at Stone Lane Gardens, and specimens from EHOK 54, gathered by Tony Kirkham, Giles Coode-Adams, Charles Howick and Bill McNamara on Hokkaido in 1997, are grown at Howick and Kew and in several private collections. The field notes of this expedition record a height of 2.5 m, with a spread of 4 m. Charles Howick (pers. comm. 2005) has found it hard to establish, and the tree seen at Howick was less than 1.5 m tall in 2005. In South Korea another group from Kew – the Kirkham, Flanagan and Boyce Expedition of 1989 – found it growing to 8 m tall at 60 m asl on Namhae Island, Kyongsangnam Province. Plants from this collection (KFBX 125) are in cultivation at Kew and at Sandling Park, Kent, where they had also reached 8 m by 2006 when measured by Owen Johnson for TROBI.