Same entry in ps.-Zonaras and, according to Adler, the Ambrosian Lexicon (703); more informatively in e.g. Apollonius' Homeric Lexicon. The headword, nominative plural of the masculine noun a)qh/r, might be quoted from somewhere but, in an entry of this kind, does not have to have been.
Actually the stalks of cereals like wheat or barley. Mentioned from Hesiod onwards; see e.g. Xenophon, Oeconomicus 18.1 ("chaff and stalks") at web address 1 below.