Both Cactaceae

Ferocactus wislizeni vs Opuntia microdasys

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.

Confused 3x by our model Method published

Side by sidefigs. a and b

Ferocactus wislizeni, photographed by er-birds
fig. a er-birds, CC BY 4.0

Ferocactus wislizeni

fishhook barrel cactus
Opuntia microdasys, photographed by sdash
fig. b sdash, CC BY 4.0

Opuntia microdasys

Bunny Ears Cactus

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Ferocactus wislizeni Opuntia microdasys 3 of 20 (15%)

The confusion runs one way only. The model mistakes Ferocactus wislizeni for Opuntia microdasys, 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 Cactaceae. The family does not separate them.
Genus Ferocactus versus Opuntia.
Flowering Peaks in August versus June. If the plant is in flower, timing helps. (n = 326 and 46.)

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.

Both recordsfull pages