Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
calcĭfrăga, ae, f. [2. calx-frango], an herb said to be a remedy for the stone, perh. hartstongue: Asplenium scolopendrium, Linn.; Plin. 27, 9, 51, § 75; Scrib. Comp. 150; 153; cf. Dioscorid. 3, 151.