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Melocactus, herbarium ghosts and red M&Ms

Posted on 29-01-2018 by Becky Desjardins

Our herbarium hides lots of interesting stories...

Some of the people who read Naturalis blogs will notice that I work not only on mammals but a few other taxa as well. These days, in between scrubbing bones and chopping up whales on the beach,  I work on cacti in the herbarium. Since November I have been working with a massive collection from the University of Leiden archives: Melocactus.

Photos: Melocacti from the Naturalis herbarium

The genus name, Melocactus which translates to “melon shaped”, and refers to the appearance of the plant: a round cactus that grows close to the ground. The entire Melocactus collection is contained in 150 boxes. They were collected  during 1884-85 in the Dutch West Indies by Dr. Willem Frederik Reinier Suringar. From the plants he collected, Suringar described 87 new species: 53 from Aruba, 30 from Curacao and 4 from Bonaire. His determinations stood for fifty years until subsequent work by two British researchers, Nathaniel Lord Britton and Joseph Nelson Rose in 1922 determined them all 87 to be only one species: macracanthos.

This extreme taxonomic “lumping” was further investigated in 1980 by botanists from Oxford. These two men spent weeks on the islands measuring and photographing Melocactus macracanthos. The Oxford researchers then were able to corroborate measurements of the sizes of macracathos and theorize that cross pollination had created one species from two different ones at some point in the islands’ history.

Photo: Melocacti are shaped like a melon.

As for Dr. Suringar, he had an illustrious career as a professor of botany at Leiden University and also as the head of the National Herbarium. He did quite a bit of plant collecting with his son, Jan Valckenier Suringar, who was also a botanist and later became head of the Wageningen herbarium. Despite his professional achievements, all was not well with Dr. Suringar. He was found dead at the Herbarium from suicide in 1898.  

Since Dr. Suringar’s death, it is believed that his ghost haunts the herbarium. Doors open and close without explanation, and furniture moves around.  That is strange indeed, but what is particularly odd is even though the collection has been moved four times to new addresses, the ghostly activities continue to this day!

 

One of the other interesting facts about melocactus is that it it is a host plant for cochineal scale. This is a type of insect, also called crimson scale or carmine beetle,  that is used to make red dye commonly found in everything from hair dye to food to clothes. During the time when Mexico was under the control of the Spanish, it was the second largest export, only behind silver. Only the female of the species is used, and it takes 70000 insects to make 2.5 kilos of red dye. The females drill their tubular mouthparts into the cactus and then extrete a wax covering over themselves for protection. They will stay affixed to the cactus for their entire lives. During the time when Dr. Suringar was collecting these plants, they were cultivated in the Dutch Caribbean specifically to host cochineal scale!

Photo: cactus with cochineal colonies

References:

Melocactus macracanthos in Habitat (1981) C.N. Rodgers and P.A. Evans, the Cactus and  Succulent Journal of Great Britain Vol 43 (⅔) p 33-36.

J. W. Sharpe, (1996) Cochineal Scale and the Prickly Pear Cactus, www.desertusa.com, https://www.desertusa.com/insects/cochineal.html