This is actually the second time that I’ve posted this species, but this post shows shows how to identify it according to the Guide to the Vascular Plants of Florida.
Peduncles (flower stems) adnate (grown together) to the petiole (flower stem) of a leaf-like bract (modified leaf):
And that’s it for the key. There are 12 other Sida species in Florida, but this is the only one exhibiting this characteristic. But because I was trying out a new field microscope, I couldn’t resist trying to photograph the tiny fruits and tinier seeds. I wonder why most texts don’t include thorough fruit and seed descriptions?