Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
aspĕrūgo, ĭnis, f. [asper], a plant with prickly leaves: Asperugo procumbens, Linn.: similis (lappaginis), sed asperioribus foliis asperugo, Plin. 26, 10, 65, § 102.