The prominence of kalo (Colocasia esculenta (L.) Schott.) in Hawaiian culture has declined after experiencing a decrease in cultivation, biodiversity and associated cultural knowledge. There was no documentation of diversity at its height. Previous estimates of biodiversity lack any sense of a methodlogical approach. A new attempt was made to assess levels of biodiversity around the peak cultivation period. Results were then compared to current levels. Nomenclatural synonymy and extinction have presented some challenges which made standard methods for quantifying biodiversity not viable. A set of new tools was used to sort through a master list of 676 varietal names. A comparison of what is known from the nineteenth century and modern time periods makes it apparent that changes in biodiversity, varietal prominence, ethnonomenclature, and ethnotaxonomy have occurred. This paper discusses the direction of such trends, and postulates a new estimate for kalo diversity at the end of the 19th century (approximately 100 years after the assumed peak of cultivation and diversity) to be between 368-482 distinct cultivars, while only 65-73 still exist today.