Poaceae and Apocynaceae
Arundo donax vs Asclepias fascicularis
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 Method published
Side by sidefigs. a and b
Arundo donax
giant reed
Asclepias fascicularis
narrowleaf milkweed
How often our model gets it wrong measured, not estimated
| When the plant was | The model said | How often |
|---|---|---|
| Asclepias fascicularis | Arundo donax | 3 of 20 (15%) |
Measured on 38,949 openly licensed, research-grade photographs. Full method and dataset.
What actually separates themon the record
| Family | Poaceae versus Apocynaceae. Different families, which is a real separation. |
|---|---|
| Genus | Arundo versus Asclepias. |
| Flowering | Peaks in November versus July. If the plant is in flower, timing helps. (n = 252 and 2,276.) |
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.