The Poisons Collection: Beware of the Honey!

The poisons collection

Today we’re putting not just one plant in the poisons collection but a genus! This genus being rhododendron. Not all but many of the species in this genus are poisonous (Robertson, 2014). So why should you beware of honey well keep reading and you will find out!

Sherlock_holmes_ver5Rhododendron are an invasive species to the UK. The particular species that causes the majority of the problem is Rhododendron ponticum. Brought over as an ornamental plant they have now spread to woodland areas replacing the natural under story (Taylor et al., 2013).

You may have heard of rhododendron from the Sherlock series. In the 2009 film it was mentioned as a proposed way to arrange a fake execution and in the BBC series it was speculated as being part of Sherlock’s fake death scheme (Skellet, 2009). It is also mentioned in Joyce’s Ulysses.

All parts of the plant contain a cocktail of toxins including andromedotoxin, grayanotoxin, rhodotoxin and acetylandromedol and the nectar is believed to have the highest concentrationRhododendron-ponticum (Robertson, 2014). However most cases of humans becoming ill not through directly ingesting the plant but through eating honey made by bees feeding off rhododendron. This honey is nicknamed “mad honey” and can even cause hallucinations (Bryce, 2014). Often its actually animals grazing on the plant. It does have the capability to kill animals or cause them to have extreme symptoms such as slow heart rate and exhaustion. Death comes from respiratory failure but this only occurs when enough foliage has been consumed (Robertson, 2014).

To conclude Rhododendrons are a beautiful yet invasive plant and one definitely to be wary and watchful of!


Bryce, E.. (2004). The Strange History of ‘Mad Honey’. Avaliable: Last accessed: 16/11/15

Robertson, J.. (2014). Rhododendron. Available: Last accessed 16/11/15

Skellett, C.. (2009). Rhododendron Poison – Truth behind the science of Sherlock Holmes. Available: Last accessed 16/11/15

Taylor, S. L., Hill, R.A. and Edwards, C.. (2013). Characterising invasive non-native Rhododendron ponticum spectra signatures with spectroradiometry in the laboratory and field: Potential for remote mapping. ISPRS Journal of Photogrammetry and Remote Sensing. 81 (1), 70-81.

ThatBiologist Everywhere!




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