What would you call the characteristic that describes division of a plant’s crown or roots for propagation?

The correct term that describes the division of a plant's crown or roots for propagation is referred to as a "clump." Clumping is a method of plant propagation where a mature plant, often perennials, can be divided into multiple sections that each contain a portion of the crown and roots. This technique is commonly used because it allows gardeners to produce new plants that are genetically identical to the parent plant, and it also helps in rejuvenating older plants by reducing competition for nutrients and space.

In contrast, the other terms refer to different concepts. A "clone" typically refers to a genetically identical copy of a plant produced through asexual reproduction methods, such as cuttings or tissue culture. A "seedling" is an early growth stage of a plant that develops from a seed and represents a new generation, not division. A "cluster" can refer to a grouping of plants or flowers growing closely together, but it does not specifically encompass the process of dividing a plant's crown or roots for the purpose of propagation.