Glottiphyllum is a genus of about 57 species of succulent subtropical plants of the family Aizoaceae. It is closely related to the Gibbaeum and Faucaria genera. The name comes from ancient Greek glottis “tongue” and phyllon “leaf”. The species are native to South Africa, specifically to the Cape Province and the Karoo desert. They grow in rocks and soils incorporating slate, sandstone and quartz. Rainfall in their native areas is between 125 and 500 mm, most of which falls in March and November. Glottiphyllum plants have thick, soft leaves arranged in pairs that are low to the ground and often graze the soil surface. They also have rhizomes. They sport yellow flowers with narrow petals in autumn and winter. The flowers are sometimes fragrant and around 5 cm in diameter. The species readily interbreed, making hybridization easy.

Glottiphyllum longum can be distinguished from its relatives by the way that its flat, green, fleshy, tongue-shaped leaves are all born in two opposite rows (distichous), lying flat and mostly prostrate along the ground. The long leaves are distinctively strap-shaped, with rounded margins. Sometimes they are also mildly curved or upturned at the tips, but not hooked. The bladder cells at the leaf margins are oriented horizontally and not elongated. The fruits are born on long stalks. The seed capsules have 9 or more locules and persist on the stem for many years. The seeds are very small and smoothed on the sides. This species is sometimes confused with the similarly widespread Glottiphyllum depressum. However the flowers and fruits of G.depressum do not have long stalks and are therefore held closely against the stem. Its seed capsule also has a very soft, spongy base, and the whole capsule degrades and falls away soon after releasing its seed. The top of the seed capsule has very thick, raised valves in a tall dome, which is surrounded by a low inconspicuous rim. In contrast, the flowers and fruits of G. longum are on long stalks, and remain on the plant for a long time. The leaves of G.longum are also often longer. G.depressum has more clearly hooked depressions on its leaves, which are also often slightly more erect. The cell walls of its leaves’ bladders cells are undulated.