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Alnus japonica (Thunb.) Steud.

Japanese alder (en), Aulne (fr)

Species

Angiosperms > Fagales > Betulaceae > Alnus

Characteristics

Trees to 20 m tall; bark gray-brown, smooth. Branches dark gray or gray-brown, striate, glabrous; branchlets brown, glabrous or yellow pubescent when young, sometimes resinous glandular. Buds stipitate, with 2 glabrous, ribbed scales. Petiole 1-3 cm, sparsely resinous glandular and pubescent; leaf blade obovate or obovate-elliptic on dwarf shoots, obovate-lanceolate on branchlets, 4-14 × 2.5-4 cm, abaxially sparsely pubescent at first, glabrescent, sometimes resinous glandular and bearded in axils of lateral veins, adaxially glabrous, base cuneate, margin remotely minutely serrate, apex mucronate, acute, or acuminate; lateral veins 7-11 on each side of midvein. Female inflorescences 2-5 in a raceme, ellipsoid, ca. 2 × 1-1.5 cm; peduncle robust, ca. 1 cm; bracts 3-5 mm, woody, base cuneate, apex rounded, 5-lobed. Nutlet obovate, 2-3 mm, with papery wings ca. 1/4 as wide as nutlet. Fl. May-Jul, fr. Jul-Aug.
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Shrub or small tree, 3-10 m; twig-ends glabrous or subglabrous, rather sharply triangular. Leaves spiral, ovate-oblong to elliptic-oblong, rather distinctly acuminate, broadly or obtusely cuneate to subrotundate at the base, soon glabrous, with small, haired domatia in the nerve-axils beneath, 6-9½ by 2¾-5 cm; nerves 6-7 pairs, slightly prominent above, more so beneath, crossbar-veins slightly prominent; petiole slender, c. 2-5 times as short as the blade, 1¼-2¾ cm. ơMale catkins 3-5 cm by 3-5 mm. Female catkins in a terminal raceme, on short-shoots, c. 0.5 cm peduncled, oblong, 1½-2½ by 1 cm. Nuts obovate-orbicular, not emarginate, c. 3 mm diam. incl. the wing c. ½ mm broad.
Life form perennial
Growth form tree
Growth support free-standing
Foliage retention deciduous
Sexuality monoecy
Pollination anemogamy
Spread -
Mature width (meter) -
Mature height (meter) 18.0 - 20.0
Root system -
Rooting depth (meter) -
Root diameter (meter) -
Flower color
Blooming months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Fruit color -
Fruiting months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Nitrogen fixer
Photosynthetic pathway c3

Environment

Wet soils along streams and in swamps and also on exposed soils. In Japan, it occurs in marsh or swamp forest with a high water table and soil conditions tending to be anaerobic with high clay and organic matter contents.
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Wet soils along streams and in swamps and also on exposed soils. In Japan, it occurs in marsh or swamp forest with a high water table and soil conditions tending to be anaerobic with high clay and organic matter contents.
Planted in secondary forest and on eroded slopes, c. 1000-1500 m, in the Philippines apparently not deciduous, frost-resistant. Fl.fr. July-Nov.
Light 6-9
Soil humidity 3-8
Soil texture 2-4
Soil acidity 3-7
Soil nutriment -
Hardiness (USDA) 4-7

Usage

Uses. Planted by the Forest Service for Reafforestation purposes.
Uses charcoal dye environmental use erosion control fuel medicinal ornamental wood
Edible -
Therapeutic use -
Human toxicity -
Animal toxicity -

Cultivation

Can be grown by cuttings or seedlings.
Mode cuttings seedlings
Germination duration (days) -
Germination temperacture (C°) -
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -35
Optimum temperature (C°) 18 - 32
Size -
Vigor -
Productivity -

Images

Leaf

Alnus japonica leaf picture by motoj (cc-by-sa)

Distribution

Alnus japonica world distribution map, present in Angola, Argentina, China, Japan, Korea (Republic of), Malaysia, Philippines, Korea (Democratic People's Republic of), and Taiwan, Province of China

Conservation status

Alnus japonica threat status: Least Concern

Identifiers

LSID urn:lsid:ipni.org:names:294936-1
WFO ID wfo-0000946310
COL ID C2QM
BDTFX ID 78755
INPN ID 162506
Wikipedia (EN) Link
Wikipedia (FR)

Synonyms

Alnus japonica f. arguta Alnus japonica f. koreana Alnus japonica Alnus harinoki Alnus reginosa Alnus japonica var. rufinervis Alnus japonica var. koreana Alnus japonica var. arguta Alnus japonica var. reginosa Alnus japonica var. latifolia Alnus japonica var. minor Alnus japonica var. villosa Alnus maritima var. arguta Alnus maritima var. japonica Betula japonica
WorldFloraDB 2024