Glabrous. Leaves opposite; lamina broadly ovate to cordate-orbicular, 7-19 by 5-13 cm, truncate to strongly cordate at the base, subsessile on a petiole 1-3 mm long, rounded at the apex, dull or slightly lustrous on either side; venation pinnate with the midrib and the main laterals visible on both sides. Inflorescencess at the nodes, a raceme or spike of (l-)2-5 opposite pairs of flowers; axis 4-14 mm long; pedicels 0-1 mm long; central bract orbicular, 2-2.5 mm long; lateral bracts 2-2.5 mm long, connate, together almost completely enclosing the ovary.
Asia-Tropical: Borneo present; Malaya (Peninsular Malaysia present); Thailand (Thailand present)
Thailand; Malesia: Peninsular Malaysia, Borneo.
In the diagnosis of M. latifolius Danser cited 3 collections, which are therefore syntypes. Haviland 2183 (K) is the most complete specimen, bearing leaves and flowers, and is selected as lectotype of the species name. Closely related to Macrosolen dianthus and M. annamicus Danser, differing from both in the strongly angular stems and the inflorescences prolonged into a short raceme. In Peninsular Malaysia, where M. platyphyllus and M. dianthus are sympatic, the differentiation is strongest, M. platyphyllus also differing in its strongly cordate subsessile leaves.