Bush beans (Phaseolus vulgaris) and runner beans (Phaseolus coccineus) can potentially hybridize under certain conditions. Both types of beans belong to the same genus, Phaseolus, which means they are closely related and have the ability to cross-pollinate.
Cross-pollination between bush beans and runner beans is more likely to occur if they are grown in close proximity and share flowering periods. Beans are typically self-pollinating, meaning they have both male and female reproductive organs within the same flower. However, they can also be cross-pollinated by insects, including bees, which can carry pollen from one type of bean to another.
The extent of hybridization will depend on factors such as the distance between the plants, the population of pollinators in the area, and the timing of flowering. Hybrids between bush beans and runner beans may exhibit traits of both parent plants and may have unique characteristics not found in either parent.
For most home gardeners, accidental hybridization between bush beans and runner beans is not a common concern, especially if different types of beans are planted at a reasonable distance from each other. If you want to prevent cross-pollination and maintain the true characteristics of each bean type, consider spacing them apart or using physical barriers like row covers.
However, if you are intentionally experimenting with plant breeding and want to create hybrid beans, you can perform controlled hand pollination by transferring pollen from one plant to another. Keep in mind that breeding beans requires some knowledge of plant genetics and controlled breeding techniques.