Mucuna (Mucuna pruriens) is known for its allelopathy to other plants due to the action of L-3, 4-dihydroxyphenylalanine (L DOPA). Activated carbon was placed in a container between lettuce seedlings and mucuna to catch the actual substance that suppresses lettuce growth. Lettuce roots closer to mucuna plants were more suppressed without the activated carbon. With activated carbon, the growth of lettuce was hardly affected by mucuna. Similar results were found in an experiment with L-DOPA samples.
