Both Dryopteris

Dryopteris carthusiana vs Dryopteris intermedia

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 Same genus Dryopteris Method published

Side by sidefigs. a and b

Dryopteris carthusiana, photographed by Yurii Basov
fig. a Yurii Basov, CC BY 4.0

Dryopteris carthusiana

spinulose wood fern
Dryopteris intermedia, photographed by Lynn Harper
fig. b Lynn Harper, CC0 1.0

Dryopteris intermedia

intermediate wood fern

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Dryopteris carthusiana Dryopteris intermedia 3 of 19 (16%)

The confusion runs one way only. The model mistakes Dryopteris carthusiana for Dryopteris intermedia, but not the reverse.

Measured on 38,299 openly licensed, research-grade photographs. Full method and dataset.

What actually separates themon the record

Family Both Dryopteridaceae. The family does not separate them.
Genus Both Dryopteris. Congeners, which is why this is hard.

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