Frangula alnus vs Rhamnus cathartica
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, 3 times. We publish the rate, and then we tell you what actually separates them.
Side by sidefigs. a and b
Frangula alnus
Rhamnus cathartica
How often our model gets it wrong measured, not estimated
| When the plant was | The model said | How often |
|---|---|---|
| Frangula alnus | Rhamnus cathartica | 3 of 20 (15%) |
The confusion runs one way only. The model mistakes Frangula alnus for Rhamnus cathartica, but not the reverse.
Measured on 38,949 openly licensed, research-grade photographs. Full method and dataset.
What actually separates themon the record
| Family | Both Rhamnaceae. The family does not separate them. |
|---|---|
| Genus | Frangula versus Rhamnus. |
| Flowering | Peaks in June versus May. If the plant is in flower, timing helps. (n = 1,528 and 420.) |
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.