Both Yucca

Yucca brevifolia vs Yucca filifera

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

Confused 10x by our model Same genus Yucca Method published

Side by sidefigs. a and b

Yucca brevifolia, photographed by Adam J. Searcy
fig. a Adam J. Searcy, CC BY 4.0

Yucca brevifolia

Western Joshua Tree
Yucca filifera, photographed by Juan Cruzado Cortés
fig. b Juan Cruzado Cortés, CC BY-SA 4.0

Yucca filifera

tree yucca

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Yucca filifera Yucca brevifolia 10 of 20 (50%)

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

What actually separates themon the record

Family Both Asparagaceae. The family does not separate them.
Genus Both Yucca. Congeners, which is why this is hard.
Flowering Peaks in March versus April. If the plant is in flower, timing helps. (n = 2,192 and 70.)

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