Cochemiea dioica vs Mammillaria heyderi
These two are not on this page because a keyword tool suggested them. They are here because our own identification model genuinely mistook one for the other, on real photographs, 5 times. We publish the rate, and then we tell you what actually separates them.
Side by sidefigs. a and b
Cochemiea dioica
Mammillaria heyderi
How often our model gets it wrong measured, not estimated
| When the plant was | The model said | How often |
|---|---|---|
| Cochemiea dioica | Mammillaria heyderi | 2 of 19 (11%) |
| Mammillaria heyderi | Cochemiea dioica | 3 of 20 (15%) |
The confusion is asymmetric, which is common and usually informative: it means one of these has a character the other lacks, rather than the two simply looking alike.
Measured on 38,299 openly licensed, research-grade photographs. Full method and dataset.
What actually separates themon the record
| Family | Both Cactaceae. The family does not separate them. |
|---|---|
| Genus | Cochemiea versus Mammillaria. |
| Flowering | Peaks in March versus March. Timing does not separate them. (n = 1,702 and 172.) |
What we do not have yet: the diagnostic morphological character that a botanist would key on, from a source we can cite. We are not going to invent one. Until we have it, this page tells you the two are genuinely confusable, how often, and what the taxonomy and the flowering data do and do not settle.