Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ădarca, ae, and ădarce, es, f., = ἀδάρκη, ἀδάρκης, a froth or efflorescence deposited on sedge, etc., forming a spongy growth, also called calamochnus; form adarca, Plin. 32, 10, 52, § 140; id. 16, 36, 66, § 167; 20, 22, 88, § 241: form adarce, Veg. 3, 48, 2; 4, 28, 15; Cael. Aur. Tard. 1, 1.