Both Persicaria

Persicaria amphibia vs Persicaria maculosa

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 Persicaria Method published

Side by sidefigs. a and b

Persicaria amphibia, photographed by Aiva Noringseth
fig. a Aiva Noringseth, CC BY 4.0

Persicaria amphibia

water smartweed
Persicaria maculosa, photographed by Daniel Cahen
fig. b Daniel Cahen, CC BY 4.0

Persicaria maculosa

spotted lady's thumb

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Persicaria maculosa Persicaria amphibia 3 of 18 (17%)

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

What actually separates themon the record

Family Both Polygonaceae. The family does not separate them.
Genus Both Persicaria. Congeners, which is why this is hard.
Flowering Peaks in August versus August. Timing does not separate them. (n = 2,271 and 1,902.)

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