Pitcher Plant Pitches In Against Invasive Hornet

By a strange turn of fate, Canada’s Purple Pitcher Plant, Sarracenia purpurea, is assisting France in its battle the invasive and aggressive Asia hornet.

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Named in honour of French botanist Michel Sarrasin de l’Etang (1659-1734), who sent plants from Quebec to fellow botanist and systemist Joseph Pitton de Tournefort (1656-1708) in Paris, S. purpurea is found in wet, nutrient-poor sphagnum bogs from Alberta east to Newfoundland – whose floral symbol it is – down into the Great Lakes and along the U.S. East Coast seaboard as far south as Florida. It is also, rather inaccurately then, known as the Northern Pitcher Plant, but also as Huntsman’s Cup, Huntsman’s Horn, even simply the Common Pitcher Plant. It has become naturalized in Ireland, the Lake District of England, Switzerland and Germany. There is also a flourish colony in the botanical gardens of Nantes in western France, where its head Romanic Perrocheau recently made an astounding observation. Thanks to the now-proverbial carelessness of Chinese exporters, the bee-killing Asia hornet, Vespa mandarinia, arrived in France in a shipment of pottery in 2004. Since then they have flourished to the detriment of both bees and humans – six French deaths have been attributed to the fearsome insects. They may have found their nemesis however in the humble Purple Pitcher Plant, which M. Perroceau has discovered stuffed with dead hornets. He believes that the pests are attracted by the S. purpurea’s nectar and pheromones. Once under the rain-protecting cover, the operculum, the hornet moves to the rim at the top of the pitcher. Once on this slippery slope there is no return. The victim slips and slides into the jug-like receptacle, there to be dissolved and absorbed by the plant’s enzyme-loaded liquids. Is there something more sinister affecting this entrapment? While it has not been determined in S. purpurea, a modest 20- to 60-centimetres tall, its larger southern cousin S. flava, the Yellow Pitcher Plant, has pitchers up to a metre tall. Its nectar has been shown to include an alkaloid drug, coniine, a narcotic to insects. The S. purpurea can be grown easily in Europe and is not considered a threat to native flora, according to BBC News, which strangely claims the pitcher plant is native to Massachusetts. As mentioned previously, they easily naturalize to northwestern Europe. It does not pose a danger to native flora though and, again according to the BBC, does not trap bees or wasps. However, closely related species Sarracenia alata, S. flava and S. leucophylla, all tall narrow pitcher plants, were recommended as traps for yellow jacket wasps by The Daily Telegraph (July 2010), available from Carnivorous Plants. Indeed the genus features eight to eleven species, most native to the southeast U.S. where they remain seriously endangered. Only S. purpurea is to be found in cool temperate climates, sometimes in surprising urban conditions. Several colonies exist in northeastern Toronto, North America’s fourth-largest city. While nobody is claiming that the Purple Pitcher Plant will eradicate the invading Asian hornet, it might assist in their control, it has been suggested. If so, it would be a remarkable gift from an observant Quebec botanist back to his Gallic homeland.

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