Morph:

in fact a lemmatiser or a `stemmer' rather than a full morphological analyser. However, in addition to producing a stem or root form for each token it is given, it also produces a normalised affix (e.g. ``ed'' for all past participle forms, both regular and known irregulars).

The Tagged Morph version only processes noun and verb tokens, as indicated by part-of-speech tags, using the tags to increase accuracy, and avoiding irrelevant tokens to increase processing speed.