A. angustifolius (synonyms are A. stenophyllus and A. tetraquetrus) is an interesting plant, with smaller and ovate leaves on the lower part of the stems, and longer and linear leaves on the upper parts. This photo illustrates only the upper parts of the stems, and the longer leaves, along with the green flowers and buds. The flowers are a relatively dull green, but with interesting red markings on the lobes. It is distributed from Peninsular Malaysia, Java, Sumatra, Sabah, Sarawak and the Moluccas. Other views of the species can be seen by clicking here and here.