A rapid method of speciation that has been important in the history of flowering plants is

Polyploidy

Explanation:

Polyploidy can be defined as a rapid method of speciation that has been important in the history of flowering plants.

In plants, it involves the possession of two complete sets of chromosomes and it leads to the origin of new species.

Hence, the two sets of chromosomes comprises of triploidy (69 chromosomes) and tetraploidy (92 chromosomes).

behavioral isolation

Explanation:

Speciation can be explained as a situation when a group within a species separates from other members of its species and develops its own unique characteristics. It can also be described as an evolutionary process by which populations evolve to become distinct species. This means that, through this process a new kind of plant or animal species is created.

The things that were known to be cause of speciation are rivers change course, mountains rise, continents drift and organisms migration.

Behavioral isolation can be described as a barrier that prevents interbreeding between closely related species because there is no mate recognition between females and males of the different species. This means the development of different behaviors that are not recognized or preferred by members in another population.

In this case, behavioral isolation has been the major driver of speciation in flowering plants, and has been the mechanism that ensure the production of viable offspring.