Small, delicate, pale green, succulent, annual or perennial herb, forming dense moss-like mats, 3-7 mm tall (to 10 mm in cultivation), 1-5 cm diam. or more (Fig. 1). Main stems unpigmented or very pale pink, filiform, prostrate, rooting at lower nodes, not ascending at tips, or scarcely so in open situations, ascending in shade, 0.2-0.4 mm diam.; branching copious, at first prostrate then ascending; length of internodes variable, up to 10 mm but mostly less than 5 mm, mostly much greater than leaves. Leaves connate, plano-convex in cross-section, ellipticlanceolate or elliptic-ovate, obtuse to subacute, 1.0-2.0-(3.5) mm long, 0.6-1.0 mm wide, 0.4-0.6 mm thick, minutely but densely papillose, mostly spreading at an angle much greater than 45° to the stem. Flowers 4-merous, solitary in leaf axils, 1-1.3 mm diam.; pedicels shorter 1 mm, elongating to c. 3 mm at fruiting. Calyx lobes ovate-lanceolate, ovate-elliptic or broadly ovate, 0.7-1.0 × c. 0.4 mm; apex ± acute. Petals ± triangular-ovate, from slightly shorter to slightly longer than calyx lobes, 0.6-0.9 × c. 0.3 mm, red in upper part; apex acuminate. Stamens 0.3-0.4 mm long. Scales minute, c. 0.1 mm long, very narrowly spathulate or clavate, pinkish. Follicles splitting along whole suture. Seeds (1)-2 per carpel, brown, 0.3-0.35 mm long, ± cylindric-ellipsoid.

Herba parva tenella annua vel perennis tegetes densas formans 3—7 mm altas. Folia in sectione transversali plano-convexa, elliptici-ovata, obtusa vel subacuta. Flores solitarii in foliorum axillis, 4-meri; pedicelli sub anthesi fere 1 mm longi, ad fructus maturitatem ad 3 mm elongati. Petala calycis lobos aequantia vel eis paulo longiora vel breviora. A C. mataikona habitu parvo, denso, musco simili, plantis 3-7 mm altis, foliis 1.0-2.0-(3.5) × 0.6-1.0 mm, floribus plerumque minoribus 1.0-1.3 mm diam., petalis plerumque calycis lobis aequantibus vel eis parum longioribus, seminibus minoribus 0.30-0.35 mm longis differt. In C. mataikona autem habitus laxe implexus, plantis 10-20 mm, foliis 1.7-3.0 × 1.0-1.2 mm diam., floribus 1.2—1.8 mm diam., petalis plerumque calycis lobis brevioribus, seminibusque 0.40-0.45 mm longis.

Small annual to short-lived perennial herb forming small, dense, moss-like mats; stems filiform, rooting at lower nodes, usually not or scarcely ascending towards tips, sometimes ascending 3-7-(10) mm high (especially in shade), much-branched. Lvs connate at base, 1-2-(3.5) × 0.6-1 mm, c. 0.5-0.6 mm thick, elliptic-lanceolate to elliptic-ovate, flat above, convex below; apex obtuse to subacute. Fls solitary in lf axils, not star-like, 4-merous, 1-1.3 mm diam.; pedicels < 1 mm long at anthesis, elongating to c. 3 mm at fruiting. Calyx lobes 0.7-1 × c. 0.4 mm, ovate-lanceolate, ovate-elliptic, or broadly ovate, acute or subacute. Petals 0.6-0.9 × c. 0.3 mm, ± triangular- ovate, greenish white towards base, otherwise red, acuminate, slightly < to slightly > calyx. Scales c. 0.1 mm long, very narrowly spathulate or clavate. Follicles smooth. Seed 0.3-0.35 mm long.