I bet you never thought plain ol’ garden geraniums could be interesting…
However, one interesting use of these Zonal Geraniums (Pelargonium x hortorum) came from the observation that a Japanese beetle would become paralyzed after eating one or two flower petals. They literally lie on their back or side with their legs extended rigidly outward—like a cartoon!
The beetle recovers after 24 hours in laboratory conditions, but if in nature the beetle is likely to be eaten or desiccated.
A rare excitatory amino acid is found to be responsible for this effect. Quisqualic acid is similar in action to L-glutamic acid (but more potent), as it functions as an excitatory neurotransmitter. Further investigation of Zonal Geranium as an insect repellant continues today; but there are other investigations in neuroscience also underway, such as use in understanding the glutamate receptors, particularly the metabotropic glutamate receptors (mGluRs), as well as furthering our understanding of neurotoxicity and excitotoxicity in such conditions such as epilepsy, stroke and Alzheimer’s disease.
The discovery of quisqualic acid in Zonal Geraniums suggests that these plants can serve as a natural beetle deterrent in gardens.
Also, you all know these plants as a “geranium”; however, they are scientifically not geraniums, but a Pelargonium cultivar that is commonly cultivated around the world.
There are about 280 species of Pelargoniums, in the family Geraniaceae, originating mostly from South Africa, but also New Zealand, Australia and the Far East.
Some species (we will get to those in later posts) are used in traditional medicine, but these Zonal Geraniums are mostly used as a cultivated ornamental species.
Zonal Geraniums are hybrids between P. zonale and P. inquinans, recognizable by the “zonal” rings or colorations on their leaves, as well as by their clusters of flowers (usually pink, red or white). They are very commonly planted in pots, windowsills or flowerbeds. They also happen to be rabbit and drought tolerant.
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**This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician.
Beetlejuice Geraniums!
