Why can you find a pepper inside another pepper?

It is possible that you have ever found a pepper in the fridge that, when opened, contained another small, green and somewhat misshapen pepper inside. It is a curious phenomenon that appears with some frequency in hollow berries, that is, fruits that have a large number of seeds that develop inside an air chamber. Like the pepper. To know how this phenomenon occurs, it is first necessary to understand how a fruit is formed from the flower .

Flower anatomy and fruit development

In general, the different floral pieces are arranged in layers, which we call whorls. From the outermost part of the flower, we have a row of usually small green leaflets, the sepals, which form the calyx , and then the petals, which form the corolla . Inside, the stamens , those parts that make pollen, make up what we call the androecium , the male reproductive system, and, finally, the carpels make up the gynoecium , the female system. Each of these floral pieces: petals, stamens, carpels… are, originally, leaves . Leaves that have been modified, shaped by evolution to fulfill functions other than photosynthesis.

Going one step further, the fruit is still, after all, the developed and matured gynoecium , which occasionally retains other floral parts. In the pepper, that gynoecium is made up of between two and four carpelar leaves . It is known how many there are by the number of internal partitions that the fruit has; each of these whitish partitions comes from the central nerve of each leaf. Those leaves fuse with each other forming a single chamber, within which the seeds develop .

Occasionally a whorl may multiply so that it has several layers instead of just one . Sometimes in landscaping that trait is selected for aesthetic reasons. Such is the case of the carnation, a flower that, in its wild version, has only five petals, but in its garden varieties it can have ten times more. Similarly, the gynoecium can double . When it happens, the outer carpels fuse to form the chamber, inside which a second chamber, a secondary fruit, develops .

A second seedless fruit

When the pollen grains come into contact with the flower, the outer gynoecium is fertilized normally, forming seeds . If the fruit is juicy, like a tomato or an orange, the secondary fruit does not have room to develop and remains embedded inside the main fruit —although it can be seen if the fruit is cut. However, in the case of pepper, the carpelar leaves maintain an internal air chamber where the secondary fruit can be housed without problems . Which, by the way, is perfectly edible.

Obviously, the external fruit, the main one, has no space limitation and is full of seeds, so the plant will allocate all the necessary resources. But the secondary does have limited space, and the pollen grains do not fertilize it, so seeds do not develop inside it. We call these fruits that develop without having been fertilized , and therefore without seeds, parthenocarpic .

A desirable mutation for the greengrocer

The development or not of parthenocarpic fruits is genetically controlled in plants. Typically, an unfertilized flower does not form a fruit. However, there are genetic mutations that allow them to develop as normal fruits . They maintain the same size, appearance and flavor as the seeded fruits, but without the seeds.

Finding seedless fruit today is relatively common, bananas , grapes, even watermelons, and a whole range of citrus fruits . In some cases, the absence of seeds is due to the fact that they are hybrid varieties, which cannot produce them; in others, it is achieved by preventing pollination. Either way, these fruits retain that mutation that allows the parthenocarpic fruit to develop . To have more plants of these varieties, vegetative reproduction is usually used, and this implies that, in these varieties, genetic variability is extremely low .

In any case, the presence of a parthenocarpic secondary pepper inside another pepper indicates that the plant has the capacity to produce this type of seedless fruit. It would not be strange if, sooner or later, they take the opportunity to start having seedless peppers in our greengrocers.

REFERENCIAS

Pérez Morales, C. (1999). Morfología de espermatófitos. Ed. Celarayn.

Tiwari, A., Vivian-Smith, A., Voorrips, R. E., Habets, M. E., Xue, L. B., Offringa, R., & Heuvelink, E. (2011). Parthenocarpic potential in Capsicum annuum L. is enhanced by carpelloid structures and controlled by a single recessive gene. BMC Plant Biology, 11, 143. https://doi.org/10.1186/1471-2229-11-143