A long-lived herbaceous plant with creeping stems forming dense mats of vegetation. Its fleshy creeping stems are much-branched and produce roots at their joints. Its alternately arranged leaves are densely clustered along the stems, but gradually become smaller and more distant from each other along the flowering stems. These small leaves (1-4 cm long) are usually green, often with numerous tiny purple spots and/or purplish margins. Its small white flowers are arranged in small stalkless clusters in the forks of the reduced upper leaves. Its tiny oblong capsules (about 1.5 mm long) have two compartments, each containing two seeds.