Asteraceae and Lythraceae

Liatris pycnostachya vs Lythrum salicaria

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

Confused 8x by our model Method published

Side by sidefigs. a and b

Liatris pycnostachya, photographed by Thomas Koffel
fig. a Thomas Koffel, CC BY 4.0

Liatris pycnostachya

prairie blazing star
Lythrum salicaria, photographed by goldfjnch
fig. b goldfjnch, CC0 1.0

Lythrum salicaria

purple loosestrife

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Liatris pycnostachya Lythrum salicaria 8 of 18 (44%)

The confusion runs one way only. The model mistakes Liatris pycnostachya for Lythrum salicaria, but not the reverse.

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

What actually separates themon the record

Family Asteraceae versus Lythraceae. Different families, which is a real separation.
Genus Liatris versus Lythrum.
Flowering Peaks in July versus August. If the plant is in flower, timing helps. (n = 829 and 13,173.)

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