Which term describes when flowers have opened?

The term that describes when flowers have opened is "bloom." At this stage, flowers have reached their full development and are ready for functions such as pollination and reproduction. The bloom stage is characterized by vibrant color, the unfolding of petals, and often a release of scent, all of which attract pollinators.

In contrast, the budding stage refers to when the flower is still in its closed, undeveloped form, while maturity might involve the overall growth stage of the plant rather than specifically the flowering aspect. The spike stage typically relates to the arrangement or positioning of flowers on a plant rather than indicating that they are open. Therefore, "bloom" is the precise term used to denote the full opening of flowers.