HEBERLING LAB

  • Welcome
  • People
  • Publications
  • Photos
  • Collected on this day!
  • Welcome
  • People
  • Publications
  • Photos
  • Collected on this day!

Collected on this day...

a weekly blog featuring specimens in the Carnegie Museum herbarium.
Each specimen has an important scientific and cultural story to tell.
This material is based upon work supported by the National Science Foundation grant no. DBI 1612079 (2017-2019) and DBI 1801022 (2019-2022). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Potatoes, Sweet Potatoes, Yams: What's the Difference?

11/21/2017

Comments

 
Potato
Solanum tuberosum​
Nightshade Family 
(Solanaceae)
Dicot
Edible stem tubers
Sweet Potato
Ipomoea batata
Morning Glory Family
(Convolvulaceae)
​Dicot
Edible root tubers
Yam
Dioscorea spp.
Yam Family
​(Dioscoreaceae)
Monocot
Edible (stem?) tubers
​
 What you know as yams are most likely not really yams.  In fact, your “classic” potatoes, sweet potatoes, and yams are all in different plant families. However, they all are widely cultivated for their nutritious starchy belowground plant structures called “tubers.” Tubers function as storage organs for the plants, providing energy for regrowth (the “eyes” or sprouting buds of your potatoes when they sit in your kitchen for too long).  Potatoes and yams technically have modified belowground stems (“stem tubers”) while sweet potatoes have “root tubers.”
 
Yam is a common name for several vine species in the genus Dioscorea (plant family: Dioscoreaceae).  They are monocots (related to grasses and lilies). Yams are widely cultivated worldwide, especially in West Africa, where 95% of the crop is harvested.  Yams can be stored for very long periods of time, making them an important crop for seasons when food is in short supply.  Yam tubers can be as large as five feet long!
 
Sweet potatoes refer to a vine species (Ipomoea batatas) in the morning glory family (Convolvulaceae).  This species is likely what is on your Thanksgiving dinner table.  In the United States and Canada, sweet potatoes are often (confusingly) referred to as “yams.”  But sweet potatoes are not even closely related to yams.  As such, the USDA requires any label with “yam” to also include “sweet potato.”  So why are sweet potatoes sometimes confusingly called yams?!  Well, this naming probably dates back to colonial times when slaves from Africa noted the similarities between some varieties of sweet potatoes to yams in Africa.
 
 And last - the “classic” potato, Solanum tuberosum.  Potatoes belong to the nightshade family (Solanaceace), which also includes many other important crops like peppers, tomatoes, tomatillos, eggplant, tobacco, and more.  Critical to the world’s food supply, potatoes are the fourth most farmed crop.  Potatoes are only distantly related to sweet potatoes.  They are also called “spuds,” which probably originated centuries ago from a term for a spade used to dig holes to plant potatoes. Having been cultivated for centuries, there are thousands of potato varieties worldwide.  The cultivated species was domesticated from wild relative potato species in South America (Peru) 7,000 – 10,000 years ago.  Important discoveries on the origin of potatoes were based on DNA from 200 year old herbarium specimens!  Similarly, the origin of the Irish Potato Famine (caused by potato late blight from a fungal pathogen) was also discovered using fungal DNA extracted from 160+ year old herbarium specimens! 
 
For more on cool new Irish potato famine research:  http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0168381
 
For more on origins of European potato: https://www.ncbi.nlm.nih.gov/pubmed/21632349
​
Picture
Specimen above: "Yam" species (Dioscorea schimperiana) collected in 1960 by A.C. Twomey in Kenya.  Yams are an important food crop across Africa.

Specimen below: "Sweet potato" (Ipomoea batatas 'Georgia Jet') collected in 2001 by Bonnie and Joe Isaac in a garden in Pennsylvania.
Picture
Specimen below:  Your "classic" potato (Solanum tuberosum) collected in 1982 from a farm in Peru.  Research suggests Peru to be the site of early domestication over 7,000 years ago.
Picture
Comments

    RSS Feed

      Suggest a specimen!

      Your birthday, favorite species, collected by your house, a particular collector, etc...?
      [object Object]
    Submit

    Archives

    October 2022
    April 2022
    January 2022
    December 2021
    November 2021
    October 2021
    August 2021
    July 2021
    June 2021
    May 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017

    Categories

    All
    Amaryllidaceae
    Anacardiaceae
    Apiaceae
    Apocynaceae
    Aquifoliaceae
    Araceae
    Araliaceae
    Asparagaceae
    Asteraceae
    Balsaminaceae
    Betulaceae
    Boraginaceae
    Brassicaceae
    Cactaceae
    Caprifoliaceae
    Caricaceae
    Caryophyllaceae
    Celastraceae
    Climate Change
    Convolvulaceae
    Cornaceae
    Cucurbitaceae
    Cultivated
    Cupressaceae
    Dioscoreaceae
    Dryopteridaceae
    Ericaceae
    Euphorbiaceae
    Fabaceae
    Fagaceae
    Geraniaceae
    Hamamelidaceae
    Holiday Posts
    Introduced Species
    Lamiaceae
    Lauraceae
    Life History Series
    Liliaceae
    Limnanthaceae
    Lycopodiaceae
    Magnoliaceae
    Malvaceae
    Melanthiaceae
    Melastomataceae
    Montiaceae
    Myristicaceae
    Oleaceae
    Onagraceae
    Orobanchaceae
    Oxalidaceae
    Papaveraceae
    Paulowniaceae
    Pinaceae
    Plantaginaceae
    Plants Of The Anthropocene
    Poaceae
    Poisonous
    Polemoniaceae
    Polygonaceae
    Primulaceae
    Pteridaceae
    Ranunculaceae
    Recollected
    Recollection
    Rhamnaceae
    Rosaceae
    Rubiaceae
    Salicaceae
    Santalaceae
    Sapindaceae
    Scrophulariaceae
    Simaroubaceae
    Solanaceae
    Staphyleaceae
    Type Specimens
    Ulmaceae
    Undetermined
    Urban Plants
    Violaceae
    Vitaceae