The loquat tree, Eriobotrya japonica, the Japanese biwa fruit tree

The loquat tree, Eriobotrya japonica, is an evergreen broad leaf tree or shrub originally native to south-central China, being most famous for its sweet, succulent fruit. Through the years it has been established in subtropical to southern temperate regions across the world and has naturalized in many places. It’s species epithet, japonica, is in truth a misnomer since it was first encountered by a westerner, the botanist Thunberg, in that country. Regardless, the plant has gained notoriety across the globe as an ornamental tree, for its fruit products, as tea (loquat leaf tea) and to a lesser extent, as a medicinal herb.

Eriobotrya japonica is a tree or large shrub of low subtropical mountain forests, attaining a maximum height of about 10 meters. Usually single stemmed, the bark is grey-brown, with smaller branches typically covered in a rusty to grey colored “wool” (a condition known as tomentose).

The broad crown is densely branched and rounded in form. The tree’s rigid, evergreen leaves are simple, broad, serrated, and deeply veined, each growing from 10-25 centimeters long. New leaves are fully tomentose and light green. They turn dark green and shiny as they age, but remain tomentose on their undersides when mature.

The flowers are borne in loose to tight clusters from late fall into early winter, and are quite aromatic. They are small, no more than 2 centimeters across, with five white petals surrounding a yellow center. The buds as well are tomentose. The flowers are pollinated in the depths of the winter months, and by spring mature into clusters of simple, round and slightly elongated fruits, brilliant orange in color and typically no more than 5 centimeters in length. These as well are have a slight fuzz to the outer skin, but inside are fleshy, juicy and sweet. Loquat seeds, usually numbering 2-4 per fruit (though there can be up to 10), account for much of the fruit’s mass, perhaps up to one third of their total weight.

The loquat is originally native to subtropical forests of southeastern Sichuan and adjacent areas of Hubei Province in south-central China. Since ancient times it has been cultivated over much of southern China, Indochina, Taiwan, and Japan. Readily spreading from seed, it naturalized in these same areas centuries ago, effectively becoming part of the native flora. In more recent years it has been naturalized throughout the world in appropriate climates stretching from India to the Middle East, throughout the Mediterranean region, parts of eastern and southern Africa, the southern USA, throughout Central America and into South America (where it grows in the cooler highlands), Australia, New Zealand, and numerous island chains including Hawaii, Bermuda, and Réunion.

This species is considered an invasive weed in eastern Australia (Queensland and New South Wales), throughout the southern USA, New Zealand, South Africa and on many islands throughout the world (for example, Lord Howe Island, Norfolk Island, Easter Island, The Galapagos, Hawaii, Réunion and Tonga).

E. japonica probably was first cultivated for its fruit. Like many other fruit trees, typical wild forms do not usually produce desirable fruit, so selective breeding was needed. Loquat trees are thought to have been cultivated in China for over a thousand years. This tree (known as biwa in Japanese) made its appearance as a cultivated plant during the late Edo Period in Japan (1603-1868), though wild forms with undesirable fruit likely had been brought centuries earlier. Loquats were first cultivated in Europe as early as the 1700’s. It is believed that Chinese immigrants brought the tree to the Hawaiian Islands in the late 1700’s.

Through the years many cultivars (some sources say nearly a thousand) have been developed the world over. Some are white fleshed, smooth skinned, extra large size (c.v. ‘Big Jim’), strawberry flavored (c.v. ‘Strawberry’), late ripening (c.v. ‘Tanaka’), and ones with simply superior taste. One important note – varieties cannot be expected to be true from seed, therefore they must be grown as grafted plants, so buyer beware! In the world Japan is the primary grower of loquat fruit, followed by Israel and Brazil.

Loquat fruit has been used in a variety of ways, sometimes eaten as is (though the skin is often removed first), made into jam and chutney, canned, stewed, to flavor dishes, added to juices, or to flavor alcohol. Mature leaves are dried and made into a tea in Japan, known as biwa cha (literally “loquat tea”). This tea is thought to have medical effects including keeping the skin young and healthy (a near fetish in Japan), as an aid against inflammatory diseases, as a cough suppressant, an appetite suppressant, and an expectorant.

A word of caution to those wishing to dive into making tea from its leaves – the new growth and seeds are chock full of cyanogenic-glycosides which if eaten in quantity can lead to dizziness, headache, palpitations, difficulty in breathing, and eventually respiratory paralysis and cardiac arrest. Amazingly, the seeds of some varieties are made into a liqueur in Italy, known as nespolino. Having said all that, the fruits are completely harmless, and in fact contain many beneficial chemicals ranging from pectin, to various vitamins and minerals, and also are a good source of dietary fiber.

Cultivation of this tree is fairly simple. They can be grown in full sun or partial shade in any reasonable soil that is not too alkaline in reaction. Rich loam, sandy humus, or even clay soils all are suitable, though the tree is probably happiest in loam soils. In their native homeland they inhabit moist subtropical forests that receive nearly continuous summer monsoon rains, and then a dry season in the winter months. This regimen is not completely necessary however since this is a very adaptive tree. Loquats are surprisingly cold hardy, taking down to -10 C (14 F) without trouble (roughly USDA hardiness zone 8). They can be maintained in colder winter areas with some protection during the worst weather, or if sited well, say in a protected courtyard or foundation planting.

One problem is that in areas where temperatures commonly drop below freezing the flowers can be killed and so no fruit will be produced. The limit for flower survival is said to be around -1 C (30 F), though plants that grow near my house in southern Japan (equivalent zone 9b) produce fruit even when winter lows have dipped to -4 C (25 F) on occasion. When living in north Florida (zone 8b) I noted that some seasons trees produced good crops, but in extremely cold years (the 1980’s were memorable) the flowers were killed off, though the trees remained healthy. Fruits typically are ripe by late spring (usually June in Japan), but can ripen earlier in milder climates. In Japan individual fruit clusters are wrapped with brown paper bags to keep insects, birds and rain off the developing fruits.

Another issue with this tree is its tendency to become invasive. In Japan it has naturalized throughout the milder regions in low, wet forests, but to my knowledge is not a truly weedy plant. In north Florida I saw many volunteer seedlings in and around human settlements, but in more established forests their presence was limited. I cannot speak for other areas where loquats are considered invasive pests, for example in Hawaii or eastern Australia, though I imagine their invasive potential is moderate at best. I’m sure some would disagree with this. Still, care should be taken when planting this tree in humid, subtropical climates since birds readily spread the seeds after ingesting their fruits.

All in all, E. japonica is lovely tropical looking tree that is both disease free and simple to grow. The main disease problem is fire blight, caused by the bacterium Erwinia amylovora. The most obvious symptom is infected branches dripping watery ooze from cankers. These need to be cut off immediately to protect the tree’s overall health, and to ensure good fruit production. Be sure to cut at least 30 cm away from the nearest canker, and be careful to sterilize the pruning tool between cuts – either by soaking it in bleach solution or isopropyl alcohol, or by heating the blades. Chemical controls include prophylactic application of liquid copper sulfate during warm, wet weather or applying antibiotic agents such as Agrimycin, especially during the blooming period. The disease spreads by entering natural openings in the plant tissue, in particular the new growth, but once established it can spread rapidly to older growths if left untreated.

The loquat is a lovely ornamental tree with the added bonus of producing large amounts of delicious, sweet fruits. Here’s another “Japanese” tree that deserves a try in suitable gardens around the world.