Baccaurea motleyana, universally known as the rambai or rambi, is a tropical fruit-bearing evergreen tree in the family Phyllanthaceae. It is native to the lowland rainforests of Southeast Asia, particularly throughout Malaysia, Indonesia, and Thailand. The genus name Baccaurea is derived from the Latin bacca ("berry") and aurea ("golden"), reflecting the clusters of brightly colored fruit, while the species epithet motleyana honors the 19th-century British plant collector James Motley. Historically, the tree has been a valued component of traditional tropical home gardens and agroforestry systems in the Malay Archipelago, prized for its reliable production of cooling, succulent fruits during the humid off-seasons.

The tree is moderately sized, typically reaching 10 to 15 meters in height, with a dense, spreading canopy of large, leathery, dark green leaves that provide excellent shade. A defining characteristic of Baccaurea motleyana is its cauliflory—the ability to produce flowers and fruit directly from the main trunk and primary branches rather than just the terminal twigs. It bears long, pendulous racemes (clusters) of round-to-oval fruits that look somewhat like large, clustered grapes or cherries. As the fruit ripens, its thin but firm skin transitions from a dull green to a vibrant yellow, brownish-yellow, or sometimes reddish-pink hue. The interior consists of three to four translucent, juicy, white or pinkish arils (flesh) that cling tightly to the seeds, offering a striking contrast to the skin.

The rambai is highly esteemed for its refreshing, sweet-to-acidic flavor profile. The flesh is soft, gelatinous, and exceptionally juicy, often described as having a taste reminiscent of a cross between a mangosteen and a citrus fruit, with a distinct, subtle "tang" that is perfect for hot, humid climates. In regional Southeast Asian gastronomy, the fruit is primarily consumed fresh, eaten out of hand as a cooling snack, or incorporated into local salads and pickles. The fruits are occasionally stewed with sugar to create a sweet, aromatic preserve or fermented into light, refreshing regional vinegars or cordials. Because the fruit is quite perishable once separated from its cluster, it is most commonly found in local village markets and is rarely exported, making it a quintessentially seasonal, hyper-local delicacy.

Nutritionally, Baccaurea motleyana is a low-calorie fruit providing a good source of dietary fiber, Vitamin C, and essential minerals such as potassium and calcium. Its biochemical profile is dominated by a diverse array of phenolic compounds that lend the fruit its antioxidant and antimicrobial properties. The flesh and peel contain high levels of vitamin C and organic acids (such as citric and malic acid), which are responsible for its sharp, refreshing acidity. The seeds and surrounding tissues are also notable for containing specific flavonoids and triterpenoids that have been investigated for their potential anti-inflammatory and hepatoprotective effects in traditional herbal applications. In village folk medicine, the leaves and bark have historically been used to create decoctions for treating skin inflammations and digestive irregularities, though the fruit remains the primary culinary focus.