The locap plant was a large plant native to Naboo that grew slowly and lived for hundreds of years. One would bore into the bedrock with its roots and siphon out plasma which it would stabilize with its digestive processes. This now safe form of plasma could be harvested from buds on the tips of their stalks.
Using harvesting subs, Gungans would farm the plasma but had to be on alert for the buds would shut if pressure was detected by the plant. As these buds were full of circular lobes with spiny teeth, harvesting became difficult.
The city of Otoh Gunga appears to have sat upon a locap limb.