Carpanthea pomeridiana is a rapidly growing, hairy, annual, leaf succulent with a spreading, decumbent growth habit. Branches are reclining, hairy to sparsely hairy, reaching a height of 150–300 mm and with a spread of 200–300 mm. The roots are fibrous. The lower main stem grows about 5 mm in diameter, the upper stems terete, 2–3 mm in diameter. The leaves are in opposite pairs, horizontal to ascending, softly succulent, flat, united at the base, and are spoon-shaped to  spear-shaped, 3.5–10 × 10–25 mm; the petiole channelled at the base, light green; the leaf margin minutely ciliate. The leaf end is acute to blunt (obtuse) to subacute.

The flowers are produced terminally, 1–3 on long pedicels, 40–170 mm long; the floral bracts 20–50 × 30–70 mm. The flowers in cymes, are rich golden-yellow and about 40–70 mm in diameter. The sepals are unequal with 2 of them leafy. Petals dense, in many series, these are linear, pointed and silk-like. Stamens plentiful, at first inflexed and later becoming spreading, exposing the stigmas. The ovary is inferior, the placentas basal, 12–20 and filiform, pointed. The fruit (receptacle) is flat, bowl-shaped and 15–20 mm in diameter and 10 mm deep. When dry hygrochastical, opening with moisture, releasing the small seeds. These are roundish angular, black, 1,5 mm in diameter, the epidermis minutely papillate.