Word of the Week: Drupe

drupe [ droop ] noun: a fleshy, simple fruit with a central stone containing the seed

 

Fruit of American holly supports birds such as the cardinal, American robin and eastern bluebird.

Ilex opaca (American holly). Photo © Elaine Mills

Shiny evergreen leaves and red fruit make holly a desirable decoration for the winter season. Although its red fruit is often called a berry, it is actually a drupe. A drupe is a simple fruit that develops from a single ovary of a flower. The outer layer of the ovary wall forms a thin skin (exocarp); the middle becomes fleshy (mesocarp); and the inner portion turns into a hard stone (endocarp) that contains the seed. Together these layers comprise the fruit’s pericarp.

Wildlife, especially birds, consume holly drupes, as they do drupes of other trees and shrubs. Be aware that many drupes, like those of holly, are poisonous to humans and pets. Children who eat them are more susceptible so if you decorate with holly remove the drupes first. In 2018, the National Poison Data System ranked Ilex species 4th in call frequency for genus-specific human plant exposure. Cherry species ranked first. (Gummin et al. 2019)

Are there drupes that people can eat? Yes, indeed. They include apricots, cherries, olives, peaches, and plums. However, all of the seeds (within the stones or pits) of these fruits (except for olives) contain a toxin amygdalin, which converts to cyanide when ingested. A whole pit swallowed without crushing it can likely pass through without harm. But eating the seeds themselves in sufficient quantity can be harmful, or even fatal. For example, in 2019 Health Canada issued an alert reminding Canadians about the risks of consuming apricot kernels. There are, though, seeds within some drupes that are edible–(domesticated or sweet) almonds, cashews, and pistachios.

The Drupes of Some Native Shrubs and Trees


NOTE: Plants in the wild should not be eaten without consulting an expert or authoritative field guides for information on identification and food preparation. It is easy to confuse plants in the wild, so you should be 100% sure they are edible before consuming them. Remember:

  • Just because a plant is not identified as toxic does not mean that it is safe to eat.
  • Sometimes only certain parts of a plant are edible and other parts of the same plant are toxic.
  • Sometimes parts are only edible at a certain time in their life cycle or when they are prepared in a certain way.

References

Bolarinwa IF, Orfila C, Morgan, MRA. 2014. Amygdalin content of seeds, kernels and food products commercially- available in the UK. Food Chemistry, 152:133–139. ISSN 0308-8146

Gummin DD, Mowry JB, Spyker DA, Brooks DE, Beuhler MC, Rivers LJ, Hashem HA, Ryan ML. 2019. 2018 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 36thAnnual Report. Clinical Toxicology, 57(12):1220–1413. https://doi.org/10.1080/15563650.2019.1677022

Thodberg S, Del Cueto J, Mazzeo R, Pavan S, Lotti C, Dicenta F, Jakobsen Neilson EH, Møller BL, Sánchez-Pérez R. 2018. Elucidation of the Amygdalin Pathway Reveals the Metabolic Basis of Bitter and Sweet Almonds (Prunus dulcis)Plant physiology, 178(3):1096–1111. https://doi.org/10.1104/pp.18.00922


 

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