A new species, Polyalthia watui, is described. It resembles Polyalthia bullata King in having bullate leaves with a cordate base, but is distinguished by its flowers with shorter pedicels, longer sepals and petals, subsessile monocarps with long stiff erect hairs; and broad-obovate leaves with fewer pairs of secondary veins. The new species is only known from Brunei's Belait and Tutong districts and is very likely endemic to the Belait geosyncline that includes these areas.

A brief introduction to research and botanical documentation of the Brunei flora, and the collaborative programme for a continuing botanical survey of the country, is given. An outline of the key biogeographical features of the Brunei area supports the premise that distinct geo-ecological enclaves occur which are special units of species richness, within which a significant level of undocumented plant diversity still exists. Jarandersonia yahyantha K.M.Wong, Joffre, Ariffin & Y.W.Low (Malvaceae), a new tree species so far only known in Brunei, is described.

Macrosolen brunsing Y.W.Low & Ariffin is described and illustrated here as a new species of aerial hemiparasite based on two collections from the Ladan Hills Forest Reserve, Tutong, Brunei Darussalam. The new species differs from all Macrosolen taxa enumerated in Borneo by its distinct linear leaves ((4-)8-14.5 cm long, 0.1-0.2(-0.25) cm wide).

A remarkable new species of Begonia sect. Petermannia (Begoniaceae) from Brunei Darussalam

No abstract