The Why and the Wherefore: Lemon-scented plants

Lemon Verbena

I’ve been asking my friend Peter why certain things smell like lemon, when they have nothing to do with lemons. (And why does lemon balm smell like lemon but look and behave like mint? – we’ll save that for another day).

I can see that Peter, a logical, scientific sort of person, is trying his best. “Plants produce scent for attraction as well as defence,” he offers. “While citrus is attractive to pollinating insects, it is repellent to aphids.”

But why do they smell like lemon… “All lemon-smelling plants share the essential oil limonene.”

But they’re not all lemons, I say.

“Why do you find that surprising?” Peter asks, incredulously. “Why is it surprising to call something with lemon in it, lemon? If you use the word red for describing the property of a plant, that’s not surprising. We are simply describing the red property that disparate plants share from a human point of view. The colour red,” he says, very slowly and emphatically, ‘Is… just… a… gene. As is a particular scent.”

Scented-leafed pelargonium ‘Lemon Fancy’

I don’t think that this line of enquiry is really holding Peter’s attention. We speak of related things.

Scents which are repellent to some insects may be  attractive to humans, just by chance. Like lemon. But scent and taste do not always correspond. The essential oil geraniol is good in soaps for instance, “But when you eat it, it’s absolutely vile!” Lemon sorbet is very good as an amuse bouche but lemon verbena sorbet is even better.

A couple of weeks later and I approach Peter with the killer question.

“What makes a lemon a lemon?”

“The same thing that makes a tomato a tomato.”

End of conversation.

Lemon thyme

Thanks for reading!

 

 

 

Ps. The winner of our photo competition will be announced today! So stay tuned…

Pps. Sarah Raven Basil ‘Lemon’ seeds are currently 40% off ♥

 

4 responses to “The Why and the Wherefore: Lemon-scented plants

  1. I love lemon scented plants, even having a potted lemon tree on the stairwell by my flat. It gives such a refreshing summery scent when the leaves are crushed. Lemon verbena is one of my new herbs this year – I’d love a recipe for lemon verbena sorbet… Any chance of a future post on this?

    • My friend Mary Montague has passed on this, though it is for sorbet and not ice cream. Mary is celebrated locally for her cooking and is married to the scientific Peter.

      Lemon Verbena Ice Cream
      (From Rick Stein’s French Odyssey, 2005)

      300ml full-cream milk
      300ml double cream
      5g lemon verbena leaves
      5 large egg yolks
      120g caster sugar
      2 teaspoons lemon juice

      Put the milk, cream and lemon verbena leaves into a non-stick pan and bring slowly to the boil. Set aside for 30 minutes to infuse.
      Beat egg yolks and sugar together in a bowl until creamy. Bring milk to the boil and strain onto the egg yolk and sugar. Mix together well, return the pan to the heat and cook over a gentle heat stirring all the time until the mixture is thick enough to coat the back of a wooden spoon. Do not let the custard boil or it will curdle.
      Leave to cool, stir in the lemon juice and churn in an icecream maker until smooth. Transfer to a plastic container and freeze for at least three hours.
      You can decorate with a sprig of lemon verbena when you serve if you wish.

      Do try it…it does taste fresh and delicious.

  2. Well I’m blowed. On reseaching the biochemistry of limonene, I find that one of its precursors is geranyl pyrophosphate, the precursor also of geraniol, the essential oil of geraniums. No wonder the two things are found together, and several similar scents are found in non related plants. Science is wonderful at times!

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