Things frequently confused with Smilax.
I've been building a list of plants that people on iNaturalist tend to call "Smilax" when they aren't. Here's what I have so far, and I'll amend it when I get other examples. These are good ones to consider if you think you've got a Smilax but aren't sure.
The top three candidates:
Carolina snailseed, Cocculus carolinus, https://www.inaturalist.org/observations/107521471
Wild yam, Dioscorea villosa https://www.inaturalist.org/observations/91003720
Autumn Clematis, Clematis terniflora https://www.inaturalist.org/observations/107062350 (notice it actually has 3-part compound leaves that are opposite on the stem).
Other foolers:
Bengal trumpet, Thunbergia https://www.inaturalist.org/observations/20442821 (Florida)
Viola, when first emerging, can look like Smilax herbacea or other non-woody Smilax.
Trillium https://www.inaturalist.org/observations/21396276
Elfin shoes Croomia pauciflora https://www.inaturalist.org/observations/47308078
Devil's walking stick, Aralia spinosa, https://www.inaturalist.org/observations/38480876
Stickseed, Hackelia virginiana (midwest) - https://www.inaturalist.org/observations/63222149
American Water-Plantain, Alisma subcordatum, especially young ones (https://www.inaturalist.org/observations/119581242).
American plantain, Plantago rugelii (https://www.inaturalist.org/observations/147341451. Notice the hairy leaf surface, which Smilax doesn't have.
Wild sarsaparilla, Aralis nudicaulis - https://www.inaturalist.org/observations/
(this doesn’t look like Smilax, but some people know the name “Sarsaparilla vine” for Smilax pumila and end up putting this label on it).
I've been fooled by some of these many times!