Perennial, erect, much-branched herbs or undershrubs. Leaves
opposite or verticillate, crenate-serrate, gland-dotted beneath. Flowers
axillary, solitary or geminate, pedicellate. Calyx 4- or 5- lobed, lobes
imbricate, ovate to lanceolate. Corolla nearly regular, limb subrotate, densely
hairy at the throat, lobes 4, subequal, imbricate. Stamens 4, subequal. Ovary
globose, ovules numerous, styles apically enlarged, stigmas notched or
truncate. Capsules ovoid to globose, septicidally 2-valved, valves thin,
entire. Seeds many, small, foveolate.