Region: South Africa.
Genus: 2 species.
BotanyHerbs; annual to perennial herbs; densely covered with strong mineralised, unicellular trichomes on cystolithic foot-cells.
Root: strong taproots.
Flowers: saucer-shaped; yellow; tetracyclic; worls of 210 to 20 parts, 12-merous polymerous; sepals free; petals are fused up to three quarter of their length; bases of the filaments are fused with the base of the corolla, forming septa and nectar chambers; gynoecium is superior and consists of two carpels, base forms a lobed nectary disc; lobes are covered with nectarostomata and secretes nectar in the nectar chambers.
Fruit: apical-loculicidal capsule.
Seeds: reticulately sculptured.
TaxonomyFormerly Codon was placed in the
Hydrophyllaceae. Recent phylogenetic analysis place it as sister group to the
Wellstediaceae and
Boraginaceae, in its own family Codonaceae in the order
Boraginales.
Recently Codon is placed in its own famliy Codonaceae in the order
Boraginales, or in the subfamily Codonoideae in the family from
Boraginaceae.
Codon is morphologically highly aberrant for
Boraginaceae, with its polymerous perianth and androecium, style inserted on the apex of an ovoidal ovary, many-seeded, sub-bilocular, loculicidal capsules, endospermous seeds with a very irregularly reticulate testa, and peculiar spines with a multicellular pedestal and unicellular apex.