What is the term for a flower cluster or the characteristic arrangement of flowers on a stem?

The term that describes a flower cluster or the specific arrangement of flowers on a stem is "inflorescence." This term encompasses various types of flower arrangements and structures, including simple clusters and more complex formations, which can significantly affect how flowers are pollinated and how they appear. Inflorescence patterns can vary widely, from a single flower on a stem to large groups of flowers that are tightly packed together or arranged in a specific way, influencing both their aesthetics and their reproductive strategies.

The other options refer to other aspects of flowers: "petal" refers to the individual colored parts of a flower that attract pollinators; "blossom" is a more general term for a flower, often used to describe the flowering stage of a plant but does not specifically denote the arrangement; and "floret" refers to a small flower that may be part of a larger inflorescence. Therefore, "inflorescence" is the most accurate term to describe the arrangement of flowers on a stem.