Both Ferocactus

Ferocactus acanthodes vs Ferocactus wislizeni

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, 7 times. We publish the rate, and then we tell you what actually separates them.

Confused 7x by our model Same genus Ferocactus Method published

Side by sidefigs. a and b

Ferocactus acanthodes, photographed by Bobby McCabe
fig. a Bobby McCabe, CC BY 4.0

Ferocactus acanthodes

California Barrel Cactus
Ferocactus wislizeni, photographed by er-birds
fig. b er-birds, CC BY 4.0

Ferocactus wislizeni

fishhook barrel cactus

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Ferocactus acanthodes Ferocactus wislizeni 5 of 20 (25%)
Ferocactus wislizeni Ferocactus acanthodes 2 of 20 (10%)

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 Both Ferocactus. Congeners, which is why this is hard.
Flowering Peaks in March versus August. If the plant is in flower, timing helps. (n = 2,917 and 407.)

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