Ophioglossaceae and Dryopteridaceae

Botrypus virginianus vs Dryopteris carthusiana

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

Botrypus virginianus, photographed by Jeff Clark
fig. a Jeff Clark, CC BY 4.0

Botrypus virginianus

rattlesnake fern
Dryopteris carthusiana, photographed by Yurii Basov
fig. b Yurii Basov, CC BY 4.0

Dryopteris carthusiana

spinulose wood fern

How often our model gets it wrong measured, not estimated

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

Measured on 38,949 openly licensed, research-grade photographs. Full method and dataset.

What actually separates themon the record

Family Ophioglossaceae versus Dryopteridaceae. Different families, which is a real separation.
Genus Botrypus versus Dryopteris.

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