Group of four pollen grains (formed from a single pollen mother-cell) that are released from the anther as one unit (e.g. in Drosera).
A cluster of four pollen grains released from the anther as a single unit.
A group of four spores formed from a spore mother cell after meiosis.
The four cells resulting from meiosis after the second telophase.
A group of four things with something in common.
A collection of four entities.
A chemical element that can bond with four different elements.