in gwwiki:
Note: these events count toward the Mordrem Problems explorer achievement. However, they are listed incorrectly in the achievement panel. “Coat yourself in Mordrem spores to baffle Mordrem defenses and gather samples from the vine chambers” earns the checkmark for “Rescue the captured workers”.
http://wiki.guildwars2.com/wiki/Coat_yourself_in_Mordrem_spores_to_baffle_Mordrem_defenses_and_gather_samples_from_the_vine_chambers