Which of the following is a characteristic of short-day flowering plants?

Short-day flowering plants are characterized by their ability to initiate flower bud development when the duration of darkness exceeds a certain length, resulting in longer nights and shorter days. This characteristic is crucial for their flowering process, as these plants typically bloom in late summer or autumn when the natural light conditions align with their requirements.

In contrast, the other options describe conditions that do not apply to short-day flowering plants. For instance, long daylight conditions are not conducive for these plants to flower, and they do not need constant artificial light to initiate flowering; instead, they rely on specific light cycles. Additionally, the ability to flower regardless of light conditions pertains more to day-neutral plants, which do not depend on day length for flowering.

Thus, the definition and behavior of short-day flowering plants firmly support the correctness of the notion that they flower when nights are long and days are short.