Description: Flacourtia rukam is a flowering plant species now recognized as belonging to the willow family, Salicaceae (it ws previously placed in the now defunct family Flacourtiaceae). F. rukam is a relatively small tree that is usually evergreen, growing to heights of about 5-15 m (~15-45 ft) tall. The trunk has long thorns up to 10 cm (4 in) long, although some cultivated varieties lack these thorns. The leaves are red to brown when young and eventually grow to be about 16 cm (6 in) long and 7 cm (3 in) wide. Mature leaves are green and more or less oval shaped with serrated edges. The yellow-green male and female flowers occur on separate individual plants (therefore it is a dioecious species); the flowers form as stalked clusters (racemes), developing from the leaf axils. The rounded fruits are about 2 cm (0.8 in) long and purplish-green to dark red in color with whitish pulp; each fruit is crowned by 4-7 small peg-like styles set in a circle. The seeds are irregular in shape.

Distribution: Flacourtia rukam is widely distributed as both a cultivated and wild species over much of Malesia, occurring as a native or introduced species in tropical or subtropical forests in China, India, and much of Southeast Asia. It is also found as an introduced species on some islands in Remote Oceania, including a few in Micronesia. F. rukam grows in evergreen humid forests up to elevations of about 1500 m (~4500 ft), frequently along the banks of the streams. F. rukam trees are mostly self sown, and root suckers are commonly produced. It is a species suitable for humid tropical and subtropical climate zones, requiring exposure to full sun or in partial shade. Generally, F. rukam has a relatively broad adaptation to soils, although it tends to develop best in those that are sandy and acidic. In Micronesia, it has been collected from Palau, Chuuk and Pohnpei. In Palau, for example, it grows in forests with limestone and volcanic soils. According to Fosberg and Sachet (1980a), the specimens of F. rukam they studied that were from Palau and Chuuk in Micronesia differed significantly from those from Indonesia, Melanesia, and Samoa, for example, “in the glabrous or subglabrous midribs of the leaves and in the subsessile stigmas on the summit of the fruit,” and thus Fosberg and Sachet classified these as a new variety, Flacourtia rukam var. micronesica.

General Uses: Although Flacourtia rukam,a tropical relative of willow trees, is cultivated for its edible fruit, these are known for their sourness and in some areas for their medicinal value. F. rukam trees occasionally to often occur as feral plants in parts of Remote Oceania (McClachey 2012), including some islands of Micronesia. The ripe fruit of F. rukam can be eaten raw, but it is often rubbed between the palms of the hand because this eliminates its astringency. In some Asian areas where it grows, this species is sometimes used in spicy fruit salads as well as pickled, or sweetened to make jam or confectionaries, and the young leaves are occasionally eaten raw in side dishes. Moreover, in parts of its natural or introduced range, the immature fruits of F. rukam are used in traditional medicine to treat diarrhea and dysentery, and the juice of the leaves is applied to inflamed eye-lids. In the Philippines a decoction of its roots is reportedly sometimes used by women after childbirth. In addition, the hard, strong wood of F. rukam is “used to make household utensils such as pestles and furniture” (Subhadrabandhu 2001; also see Puccio N.D.); for example, in Futuna (i.e., Horne Island of Western Polynesia), the wood of this species is reportedly used in construction (see Bishop Museum Herbarium voucher specimen BISH #34823, Flacourtia rukam, D. Yen collector).

Uses in Palau: Many collections of specimens of “Flacourtia rukam var. micronesica Fosberg & Sachet” have been made in Palau over decades of field research (e.g., see http://www.hear.org/pier/species/flacourtia_rukam.htm). In Palau, young leaves of F. rukam are reportedly “used medicinally for dizziness and venereal disease,” and the fruits are eaten (Kitalong et al. 2008:77).

Uses in the Mariana Islands: Raulerson (2006) reported Flacourtia rukam as an introduced species on Guam; however, there is a paucity of information available about the cultivation, use or spread of this small tree in Guam or elsewhere in the Mariana Islands.

Uses in Chuuk: According to Space et al. (2000:14, 17), Flacourtia rukam is one of a number of introduced plant species in Chuuk that are invasive elsewhere in similar ecosystems, but have not yet become widely naturalized in Chuuk; this needs to be confirmed and monitored. Although F. rukam may not be invasive now, or in the future in Chuuk, there are a number of recorded voucher specimens of “Flacourtia rukam var. micronesica Fosberg & Sachet” collected on the various volcanic island remnant located within the large lagoon of this almost atoll (e.g., see
http://www.hear.org/pier/species/flacourtia_rukam.htm; also see Fosberg and Sachet 1980).