Tree, up to 19 m high, dbh 2-25 cm, outer bark smooth, dark green to blackish brown, inner bark yellowish to ochre, thin. Branchlets rough to smooth, greenish brown to greyish black to reddish black; Leaves 1-4-jugate; Inflorescences axillary, thyrsoid, branching at the base, to 19 cm long, laxly puberulous; Flowers c. 7 mm in diam. Sepals: Petals broadly obovate, c. 2.5 by 2 mm; Stamens 8; Ovary c. 1 mm high, densely sericeous; Fruits ob-cordatiî, attenuate at the base, 1.5-1.7 by 1.3-1.5 cm, outside rugose, very laxly puberulous, inside smooth; Seeds not observed.
Asia-Tropical: Borneo present (Kalimantan present); Sulawesi (Sulawesi present), Beluran District present, Kota Belud present, Mali-li present, Minahassa present
Malesia: Borneo (Kalimantan: Kota Belud and Beluran District), Celebes (Mali-li, Minahassa).
Rhysotoechia koordersii shows an overall similarity with R. ramiflora, although there are a few differences. These are best observed in the specimens of both species from Celebes. The overlap in the third character in the table below is caused by the R. koordersii specimens from Kalimantan. The di fferences are, in my opinion, large enough for R. roordersii and R. acuminata to remain separate species, although they must be closely related.
|R. ramiflora||ovate to elliptic||acute to cuspidate||7-22 mm|
|R. koordersii||obovate to elliptic||obtuse to acuminate||0-10 mm|