Glowstem
Nocturnica illuminati
The Glowstem is a plant in Pikmin 2. It emits red or green light and is found underground, only where the terrain is metallic. It seems that it may not be a plant because it resembles the real-world object an LED (light-emitting diode), with its two wires stuck in the ground, supposedly as roots. Otherwise, a plant could only have undergone an evolution and have been melded with the device, making it an unnaturally created life-form.
Olimar's Notes
Although they are obviously unrelated, the glowstem bears a striking resemblence to the street lights on Hocotate. It is highly possible that glowstems could be a relic of some unknown civilization beyond the scope of our imagination.
Louie's Notes
Inedible. Known effects include uncontrolable episodes of impromptu break dancing.