The Glowcap Family is a family in Pikmin 2, it contains two harmless pikmin plants. They both glow a little bit, and can only be found underground. They are only used for scenery.
Common GlowcapMain Article: Common Glowcap
Common Glowcaps are pale-blue mushrooms that don't have any purpose, besides scenery. They are only found underground.
GlowstemMain Article: Glowstem
These are not so much plants, they are LED with a green or orange light. They are also only used for scenery. If Olimar touches them, they will be put out for a second.