Principal English Translation: 

wild potato, heartleaf horsenettle, or heartleaf nightshade (see attestations)

a plant with an edible root, or the root itself
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 215.

Orthographic Variants: 
Alonso de Molina: 

cimatl. cierta rayz de yerua.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 22r. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

CIMA-TL a plant (Desmodium amplifolium) the well-cooked root of which is used to season stews / cierta raiz de yerba (M), planta cuya raiz su usa en guisados (S) [(1)Rp.75].
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 35.

Attestations from sources in English: 

"It is commonly known as cimatli (along with S. ehrenbergii), heartleaf horsenettle, or heartleaf nightshade. This is one of the few wild potato species that was commonly used as food. The Aztec and the Chichimeca ate S. cardiophyllum and the practice continues in some parts of Mexico today (Johns 1990). In fact, there was at least one farm that was growing S. cardiophyllum, S. ehrenbergii, and S. stoloniferum for market in Jalisco as recently as 2010 (Villa Vazquez 2010)." The leaves are shaped like hearts.
"Solanum cardiophyllum," Cultivariable,

See also: