Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sagmen, ĭnis, n. [root sag, to fill, feed; cf. Gr. σεσαγμένος, σάττω; Lat. sagina], the tuft of sacred herbs plucked within the citadel by the consul or prœtor, by bearing which the persons of the Roman fetiales and ambassadors became inviolable: sunt sagmina quaedam herbae, quas legati populi Romani ferre solebant, ne quis eos violaret, sicuti legati Graecorum ferunt ea, quae vocantur cerycia, Dig. 1, 8, 8; cf. Fest. p. 320 Müll.; and Paul. ex Fest. p. 321 ib.; Plin. 22, 2, 3, § 5; Liv. 1, 24; 30, 43.