Dimocarpus longan Lour.

Trees, exceptionally shrubs, up to 30(-40) m high, dbh up to 30(-80) cm, buttresses up to 2 m high. Twigs terete with 5 faint grooves, 3-11 mm in diam., whitish to dark brown, mostly inconspicuously, sometimes warty lenticellate, rather densely ferrugineous-tomentose with tufted hairs, mostly glabrescent. Leaves 2-4(-6)-jugate, axial parts variably, mostly densely hairy; petiole 3-20 cm long, (terete to) flattened above; petiolules 0.2-35 mm long, mostly grooved above. Leaflets elliptic (rarely ovate) to (ovate-)lanceolate, 3-45 by 1.8-20 cm, index 1-5, stiff-chartaceous to coriaceous, with or without naked glands or hair tufts in part of the nerve axils beneath, above often tomentose in basal part of midrib, beneath thinly tufted tomentose mainly on midrib and nerves, between the nerves often with paired or solitary hairs or sub-glabrous; base equal-sided to oblique, acute to rounded, rarely decurrent; margin entire; apex sometimes obtuse to acute, mostly tapering acute-(to obtuse-)acuminate; midrib sunken (rarely flat to raised) above, nerves 0.4-3 cm apart, angle to midrib 45-90°, straight to slightly curved, at least in lower half of leaflet not joined, above slightly prominent to faintly grooved, veins mostly ± scalariform, rather dense, above often inconspicuous, beneath more or less prominent, veinlets reticulate, on both sides prominulous to hardly visible. Inflorescences 8-40 cm long, densely tufted-tomentose; branches few to several, solitary or sometimes paired, ascending, often rather long, partly and sparsely branched, upper parts of branches and branchlets bearing many subsessile to distinctly stalked (1-)3-5-flowered cymules; bracts patent, oblong-ovate to narrowly lanceolate, 1.5-5 by 0.6-1.5 mm; pedicels 1-3 mm long, rather slender. Sepals 2-5 by 1-3 mm, inside at least partly variably short-hairy. Petals 5, broadly to narrowly spathulate, 1.5-6 by 0.8-2 mm, both sides for the greater part densely woolly (big ones) to subglabrous (small ones), apex especially inside if not woolly with sessile glands. Disc velutinous. Stamens: filaments 1-6 mm long, mostly woolly (hairs often tufted) except at base and less often at apex; anthers 0.6-1.5 mm long. Fruits: lobes broad-ellipsoid to globular, 1-3 by 1-3 cm, smooth to warty or with spines up to 1 cm long, sometimes granular, glabrescent.

A tropical plant. It will grow in poorer soils and colder conditions than a litchi. It can stand frost and needs a period of cool temperature to fruit well. So they suit a subtropical to warm temperate climate, but will also grow in the lowland tropics. The chilling requirement is less than litchi which means it will fruit in more tropical areas. It does best with temperatures between 19-26°C. They can tolerate wind but drying winds at flowering affect fruit set. Excessive rainfall during flowering reduces fruit set. It suits monsoonal regions with a distinct wet and dry season. They can tolerate flooding for a few days. A rainfall of 1,500-2,000 mm is best. A pH of 4.5-6 is best. In XTBG Yunnan. It suits hardiness zones 11-12.

Longan is commercially grown for its sweet fruit. Major producers include China, Thailand and Taiwan, with important crops in India and Vietnam, while Australia is a minor producer with Longans mainly grown on the Atherton Tableland in north Queensland and smaller plantings as far south as Byron Bay in northern New South Wales (Menzel & McConchie 1998; Keogh, accessed 2020); see also Lithanatudom et al. (2017). Also reported to have potential medicinal uses (e.g. Wang et al. 2011, Lithanatudom et al. 2017, and references therein). In Asia the wood is sometimes used for construction timber or for furniture, and the seeds, which contain saponin, are sometimes used as a soap substitute (Leenhouts 1994).

Seedlings do not produce true to type and take up to 20 years to fruit. So air layered or grafted plants are used and these fruit in 3-4 years. For air layering, mature shoots about 2-3 cm across are chosen which do not have active vegetative growth. A ring is cut around the twig 50 cm from the tip removing the bark and soft wood. A plastic sleeve is put over the twig and tied below the cut ring. Then peat moss or rooting mix is filled into the sleeve and this is tied off above the ring. When roots have formed the twig is cut off and planted. Cuttings and budding can also be used. Spacing needs to be 5-8 m apart. Deep rooting needs to be encouraged by good site preparation. This stops trees being blown over. Wind protection is essential. Although flowers need to be cross pollinated, this can be done between flowers on the same tree as flowers develop at different times. Very little pruning should be done. Fruit need to ripen on the tree. They do not ripen further after harvest.