This defect is most often referred to as ‘shells’ or sometimes ‘ears’, we’ve even heard the term ‘elephant ears’ while researching this topic. They are thus nicknamed for obvious reasons – they look just like that part of the anatomy. These should not be confused with broken beans which will be covered in the next lesson. This defect is problematic for farmers because, like peaberrys, yields can be reduced when plants produce a high number of empty beans. Scientific literature is not robust on this subject with the most comprehensive research dating back to the 1940s. It is reported that this defect is only encountered with interspecific hybrids such as the Timor hybrid which was a natural crossing of robusta and arabica. (Ferwerda, F. P., 1948)
The issue arises in hybrids of plants with differing numbers of chromosomes e.g.