Principal English Translation: 

mistletoe, hay, chaff or refuse of plants (see Karttunen); see also tlapachtli (thatch for roofing) and apachtli (marsh hay or palm)

Orthographic Variants: 
Alonso de Molina: 

pachtli. malhojo, o cierta yerua que se cria ycuelga enlos arboles.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 79r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

PACH-TLI mistletoe, hay, refuse of plants / malojo o cierta yerba que se cria y cuelga en los árboles (M), heno (T) [(3)Tp.128,172,(10)Zp.44,85,87,148,149,152,179,181,224]. CUAUHPACH-TLI is Spanish moss. The sense common to the many uses of PACH-TLI is of worthlessness, parasitism, or refuse with respect to plants.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 183.