Alnus japonica commonly known as Japanese Alder is a conical to pyramidal deciduous tree that is native to temperate forests, streambanks, swamps and roadsides in north-eastern Asia and Japan. It usually grows 3 – 10 metres tall, exceptionally to 20 metres. The bole is usually short, especially in trees grown in the open where the lower branches are generally retained. It is deciduous in most of its range; the tree has adopted an evergreen habit where it is grown in the Philippines. Although a plant mainly of temperate regions, it does extend south to Taiwan where it enjoys a subtropical climate and is also cultivated in the Philippines, usually at higher elevations. Grows best in a sunny position, but is shade tolerant. Prefers a heavy soil and a damp situation, but it succeeds in ordinary garden soil. It grows well in heavy clay soils. It does not require fertile soil, but prefers permeable soils and should not be planted in compact soils. It thrives in drier soils than many members of this genus. It tolerates very infertile sites. Tolerant of inundation of the soil, under such conditions the tree retains its leaves and can almost maintain its growth rate by forming adventitious roots. A fast-growing tree – on fertile sites, poles and firewood can be harvested after 5 years, small-diameter timber can be harvested in less than 10 years. The tree responds well to coppicing. This species has a symbiotic relationship with certain soil micro-organisms; these form nodules on the roots of the plants and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby.