Which laborious process pertains to coming into bloom or to develop fully?

The term "effloresce" specifically refers to the process of coming into bloom or developing fully, particularly in relation to flowers and plants. In a broader context, it can also describe any process of thriving or flourishing. This aligns directly with the idea of growth, transformation, and reaching a state of maturity.

In contrast, the other terms carry different meanings. "Initiate" implies the beginning of a process rather than its completion or full development. "Stagnate" signifies a lack of progress or growth, and "abandon" suggests giving up or leaving something behind. Therefore, they do not reflect the concept of blooming or achieving full potential as succinctly as "effloresce" does.