ORGLIST: Re: Help identify this plant/fragrance

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From: Jack Sullivan (jsulliva$##$eclipse.net)
Date: Sat May 16 1998 - 11:28:23 EDT


> >Anyway, it seems to me that fragrance is the most difficult thing to
> >describe.
> Gymnocalycium multiflorum and Astrophytum myriostigma responded with bloom.
> Both of these plants have fragrant blooms but the scent is impossible to
> describe. I can only say that the Gymno bloom smelled good enough to eat -
> like fresh vegetables?!!
>
> Desert Rat Dave

A. myriostigma appears to have a complex, floral scent made up of a
mixture of several volatile chemicals, some of which are probably
terpenes like linalool. I've seen 1 report where someone described it as
lemon-citrus, but that may have been a different plant or a variety.

I have a big interest in identifying these aroma components and perhaps
using them as chemotaxonomic markers. What is required is a small
suction pump that draws the aroma mixture through a canister of
activated charcoal. The canister is then taken to a well-equipped lab
where the chemicals are flushed into a solvent that is then injected
into an analytical device called a gas chromatograph. This separates the
individual chemical components, which are then fed one by one into
another instrument called a mass spectrometer. The results obtained can
be used to identify each componment as well as its percent composition
in the aroma. (This procedure is known as "head space analysis.")

A Swiss group employed this technique some years ago and compared the
fragrance of the related plants Hoya carnosa and Stephantotis floribunda
(Asclepiadaceae). Their results were reported in the journal Asklepios.
They were studying the variation of the aroma during a full day,
switching charcoal canisters every few hours and analyzing each
separately. Interestingly, one component in Stephanotis peaked in
concentration in the late evening while another peaked in the early
morning, perhaps an adaptation to pollinators with different sleeping
habits!

I'd be interested in collaborating with anyone who has access to the
$50,000 or so worth of analytical instrumentation needed to perform this
type of analysis.
--
Jack Sullivan
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