I was hiking near Lake Chaplain on Sunday and found the strangest horsetail specimen I have ever seen. The specimen appeared to be a E. telmateia stem with both fertile and sterile characteristics. Specifically, it appeared to have a stem with branches (typically on sterile stems) and a strobilus (typically on fertile stems). Images of the specimen can be found here: https://www.inaturalist.org/observations/26702147

I have three questions that are uniquely relevant to this group.

1. Is the E. telmateia? E. sylvaticum can have morphology like this, but this observation is extremely unlikely to be that species?
2. Is this something that is natural? An odd mutation? A confused E. telmateia?
3. Do you have any recommendations for cataloging other kinds of morphology in a consistent manner? This specimen doesn’t neatly fall into the three “Sterile”, “Fertile”, and “Fertile/Sterile” categories.

I am very interested to hear thoughts from the iNat community about these questions! This observation has got me scratching my head and thinking about how this project can accommodate the diversity of real-world horsetail morphologies.