Nephelium cuspidatum fruit

What it is

The fruit here is Nephelium cuspidatum variety eriopetalum. Each round or oval fruit measures 2–4 cm (0.8–1.6 in) long and 2–3 cm (0.8–1.2 in) wide. It turns red at maturity, often with a dense covering of thin projections. These can look like threads or narrow straps, straight or curved.

Inside is the edible white coating around the seed. Its botanical name is sarcotesta; it is the fleshy part of the seed’s covering. In eriopetalum, that flesh has a sourish flavour.

Where it comes from

Eriopetalum grows in Peninsular Malaysia, Sumatra, Java and Borneo. It belongs to lowland rainforest, both untouched forest and forest that has regrown after clearing, usually on ridges and slopes.

In Malaysia and Singapore, sanggul lotong is one of its names. In Indonesia it is also called deket, rambutan kabung or ranggung.

How it's eaten where it grows

In Borneo, eriopetalum is grown for fruit in home gardens. The edible part is the white flesh surrounding the seed. Eriopetalum and robustum are two fruit-growing varieties within Nephelium cuspidatum, a species with six named varieties; the sourish white flesh described here belongs to eriopetalum.

How it's grown

The tree can reach 40 m (130 ft), sometimes with small flared roots at the base of the trunk. New trees grow from seed, and insects pollinate the flowers. In cultivation it grows in full sun with moderate watering and fertile soil that drains well.

When and where you'll find it

Borneo’s home gardens are one place this fruit is grown. The lesser rambutan relatives are only rarely traded, and then locally. On Indonesia’s Bangka Island, Tua Tunu Botanical Garden in Pangkalpinang keeps three Nephelium cuspidatum trees.