Both Nuphar

Nuphar lutea vs Nuphar polysepala

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 Nuphar Method published

Side by sidefigs. a and b

Nuphar lutea, photographed by Jason Grant
fig. a Jason Grant, CC BY 4.0

Nuphar lutea

yellow water-lily
Nuphar polysepala, photographed by Erin Springinotic
fig. b Erin Springinotic, CC0 1.0

Nuphar polysepala

western yellow pond-lily

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Nuphar lutea Nuphar polysepala 2 of 18 (11%)
Nuphar polysepala Nuphar lutea 5 of 20 (25%)

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 Nymphaeaceae. The family does not separate them.
Genus Both Nuphar. Congeners, which is why this is hard.
Flowering Peaks in June versus June. Timing does not separate them. (n = 1,468 and 630.)

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