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Sophora japonica

Pagoda tree

Pagoda tree (Eng), acacia del Japón, sófora, árbol de las pagodas (Spa), sofora, acàcia del Japó (Cat), (Baq), acacia do Xapón, sófora do Xapón (Glg), acácia-do-Japâo (Por).

Non-native

DID YOU KNOW...? This species is called the pagoda tree because in eastern Asia it is traditionally cultivated near temples and cemeteries.

DESCRIPTION

This tree can be up to 15-20 m tall, with a wide, rounded, and globose crown. The bark is brown and very cracked; it has no thorns and the young twigs are greenish in colour. The leaves are deciduous, alternate and compound with 3-10 pairs of, usually opposite, leaflets and a further terminal leaflet (odd-pinnate). These leaflets are 3-7 cm long and 2-3 cm wide. They are ovate, oblong, pointed at the tip, with a fine down that sometimes goes unnoticed. The underside is bluish-green in colour.

The cream-coloured flowers are borne in the middle of summer in very large groups, sometimes having a pinkish tint. The penetrating aroma of the blossom is pleasant and attracts many insects, particularly bees, and this is considered a good plant for honey. When they dry up and fall off, sometimes the flowers create a characteristic yellowish carpet under the crown. Another peculiarity of the flowers is that all the stamens (the male part of the flower) are free, something very unique in legumes. The fruit of this legume is peculiar, as it is cylindrical, 3-7 cm long by 0.9-1.5 cm wide, and when mature has necks, or kinks, that constrain the seeds. In addition, the fruits are indehiscent, i.e., they do not split open when ripe. This differentiates it from the true Acacias (genus Acacia), the black locust (Robinia pseudoacacia) and the honey locust (Gleditsia triacanthos).

ECOLOGY

It can withstand low temperatures, the heat of summer, droughts, and the saline influence of the sea. It prefers deep soil that is not waterlogged for long periods of time. It also suffers if the substrate is very dry, or very compacted. It grows quickly, is resistant to pruning and pollution, resprouts easily from the rootstock, and germinates easily from seed. On the other hand, it is not a very long-lived species. In its natural range it grows in deciduous forests, on riverbanks and in valleys, but when established in the wild this species is more to adapted to watercourses than the honey locust (Gleditsia triacanthos).

DISTRIBUTION

The pagoda tree is native to central, northern and north western China, and Korea. Its original range did not include Japan, despite its specific name, although it was introduced in ancient times and today is widespread in that country. It was brought to Europe in the 18th century by the French botanist Jussieu, when it also arrived in Spain, although it was not grown on a large scale until the 20th century. It is now used frequently as an ornamental in many parks, gardens and along streets throughout the Iberian Peninsula. It has become an invasive species in the United States, Australia and South Africa, and in the Iberian Peninsula it has gone from being naturalised and appearing in some areas subspontaneously to being an invader in some inland provinces.