Both Trillium

Trillium cernuum vs Trillium erectum

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

Confused 6x by our model Same genus Trillium Method published

Side by sidefigs. a and b

Trillium cernuum, photographed by Pierre Cartier
fig. a Pierre Cartier, CC0 1.0

Trillium cernuum

nodding trillium
Trillium erectum, photographed by Mason Heberling
fig. b Mason Heberling, CC BY 4.0

Trillium erectum

red trillium

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Trillium cernuum Trillium erectum 6 of 20 (30%)

The confusion runs one way only. The model mistakes Trillium cernuum for Trillium erectum, 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 Melanthiaceae. The family does not separate them.
Genus Both Trillium. Congeners, which is why this is hard.
Flowering Peaks in May versus May. Timing does not separate them. (n = 1,971 and 17,064.)

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