Reading C-numbers and field codes: what those cryptic Lithops labels mean

A field code records where a specific seed collection was made in habitat. It is not a taxonomic rank and not a cultivar name. It is provenance — the equivalent of a wine vintage's vineyard plot.

A code like C123 tells a collector this seed traces back to a numbered population, often pinpointed to a single hillside. Two plants of L. lesliei from C001 and C310A may look noticeably different because they come from genetically distinct wild populations.

C-numbers (Cole) are the most widely used. They derive from the seminal field work of Desmond and Naureen Cole, published in their 2005 monograph on the genus, and cover most named populations of every Lithops species.

MG numbers come from Mesa Garden seed lists. SH and SB numbers come from collectors Steven Hammer and Steven Brack. Each system uses its own numbering — they are not interchangeable, so MG200 and C200 are different things.

Two practical reasons: predictability and pedigree. A C-number lets you anticipate adult morphology — body colour, window pattern, mature size — because populations are visually consistent.

For collectors, a documented code is also the only honest way to call a plant a particular form. 'Lithops lesliei var. lesliei C015' is a specific, verifiable claim; 'Lithops lesliei red form' is anyone's guess.