Both Bromus

Bromus diandrus vs Bromus tectorum

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 Bromus Method published

Side by sidefigs. a and b

Bromus diandrus, photographed by John Lyden
fig. a John Lyden, CC BY 4.0

Bromus diandrus

great brome
Bromus tectorum, photographed by Shane Johnson
fig. b Shane Johnson, CC0 1.0

Bromus tectorum

Cheatgrass

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Bromus tectorum Bromus diandrus 3 of 19 (16%)

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

What actually separates themon the record

Family Both Poaceae. The family does not separate them.
Genus Both Bromus. Congeners, which is why this is hard.
Flowering Peaks in April versus May. If the plant is in flower, timing helps. (n = 231 and 215.)

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