Mostly herbs or undershrubs; stem herbaceous or woody, rarely twining; branches terete or quadrangular. Leaves opposite or temately whorled. Stipules mostly connate with the petiole forming a 2-multi setose sheath, rarely entire, persistent. Inflorescence an axillary or terminal cyme. Flowers very small, white. Calyx-tube obovoid, globose or turbinate, lobes 4, acute, persistent, contiguous on the capsule. Corolla infundibuliform or campanulate, rarely rotate, throat glabrous, pilose or barbate, lobes 4, linear, ovate, valvate in bud. Stamens 4, inserted in the throat or tube of the corolla; anthers slightly exserled, linear-oblong or shortly rotundate; dorsifixed, disc fleshy, inconspicuous. Ovary 2-lcculed, ovules numerous, style filiform, stigma 2-fid or 2-lobed. Capsule small, ovate, apex subattenuate, septicidally, loculicidally or totally longitudinally dehiscent or separated into 2 indehiscent cocci. Seeds numerous, angular and planoconvex.
Many botanists (Torrey & Gray in Fl. N. Amer. 2(1): 37-43. 1841, Fosberg in Va. J. Sci. 2: 106-111. 1941 & in Castanea 19: 25-37. 1954, Lewis in Rhodora 63: 216-223. 1961 etc.) are of the opinion that Oldenlandia L. and Hedyotis L. should be merged, however, following Verdcourt (in Polhill, Fl. Trop. East Afr. Rubiaceae-I, 1976), we have kept them separate. Moreover in Pakistan Oldenlandia and Hedyotis have distinct facies although the differences in the two genera are frequently trivial.