What characteristic defines florist's foam when it is adequately saturated?

Florist's foam, when adequately saturated, will undergo a change in texture, becoming less rigid and more pliable. This characteristic is vital for floral arrangements, as the foam must be able to securely hold the stems of flowers while also allowing for easy insertion and repositioning.

When florist's foam absorbs water, the cellular structure swells, leading to a softer feel. This transformation enables the foam to maintain its ability to support floral materials while providing the necessary moisture to keep the flowers hydrated. The change in texture is crucial for florists, as it ensures that the flowers are well-supported but also allows for an aesthetic and flexible arrangement.

The other characteristics mentioned in the options do not accurately describe the result of proper saturation. For example, the idea that it becomes too soft to hold flowers contradicts the purpose of using florist foam, which is designed to hold flowers firmly yet adaptably. Similarly, retaining too much water and becoming heavy is not the case when the foam is adequately saturated, as it is meant to optimize moisture without becoming cumbersome. The appearance of a darker color and being lightweight may occur, but they do not encapsulate the primary characteristic of the foam's texture change, which is the most significant factor in its effective use.