Both Asclepias

Asclepias speciosa vs Asclepias syriaca

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

Confused 5x by our model Same genus Asclepias Method published

Side by sidefigs. a and b

Asclepias speciosa, photographed by Craig Martin
fig. a Craig Martin, CC0 1.0

Asclepias speciosa

showy milkweed
Asclepias syriaca, photographed by webohms
fig. b webohms, CC BY 4.0

Asclepias syriaca

common milkweed

How often our model gets it wrong measured, not estimated

When the plant was The model said How often
Asclepias speciosa Asclepias syriaca 5 of 20 (25%)

The confusion runs one way only. The model mistakes Asclepias speciosa for Asclepias syriaca, 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 Apocynaceae. The family does not separate them.
Genus Both Asclepias. Congeners, which is why this is hard.
Flowering Peaks in June versus June. Timing does not separate them. (n = 4,532 and 8,731.)

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