huitztli (Mdz47r)
This element for the word thorn or spine (huitztli) has been carved from the compound sign for the place name, Huitztlan. It is upright, with the point at the bottom. The thorn has thorns of its own along what for the viewer is the left side. That side is also red, recalling blood. The right side is turquoise blue.
Stephanie Wood
As our Online Nahuatl Dictionary attests, thorns and spines were used in self-bloodletting, and one of the objectives was to get blood onto the spine. This explains the red coloring of spines. This has an an association, in turn, with warfare and with religious offerings.
Stephanie Wood
c. 1541, but by 1553 at the latest
Stephanie Wood
thorns, spines, blood, sacrifice, sacrificio, ofrendas, sangre

huitz(tli), thorn or spine, https://nahuatl.wired-humanities.org/content/huitztli
Codex Mendoza, folio 47 recto, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 104 of 188.
The Bodleian Libraries, University of Oxford, hold the original manuscript, the MS. Arch. Selden. A. 1. This image is published here under the UK Creative Commons, “Attribution-NonCommercial-ShareAlike 3.0 License” (CC-BY-NC-SA 3.0).