[awagsFare]

Another lemon scented one , which reminds me of lollies is Lemon verbena, Aloysia citrodora , small shrub to a couple of metres, depending on where you live.

Also the Basil genus, Ocimum sp. has a vast arrray of different scents, Menthol, lemon, cloves, mint, lime...and the list goes on and on.

Then there are the Pelargonium sp. they have , orange, mint, lemon, rose, etc,. etc,.

I too like Woolybutt am intrigued as to how all these varying Genera of different Family have similar scents??

Interesting topic !

The answer to that lies in the biochemistry of the plants. Many of the odour compounds have chemical similarities. This was observed by Wallach and formulated into his isoprene rule in 1887. This says that the naturally occuring terpenes can all be built up from isoprene units joined together in various ways. The basic skeleton can then be modified by oxidation etc. Terpenes form one of the major groups of aromatic chemicals in plants. They can be interconverted by chemical means in countless ways. Wallach's original observations have been modified by more recent researches to account more closely with evidence from biochemistry. Examples of this class of of compound are; terpentine, menthol, eucalyptus.

Another group of chemicals is the phenylpropanoids. These are considered to be derived ultimately from glucose, via the shikimic acid pathway. Some familiar smells associated with this type of compound are, cloves, huon pine, vanilla.

[GeraldCortis]

Thanks morrie.

[awagsFare]

Thanks morrie.

My pleasure, rb. This stuff has been one of the passions of my life. Even more than mushrooms!

[GeraldCortis]

one of mine also.. as it goes..

[soonahonsefalh]

I'm about to have dinner, and Morrie has hanbdled it anway - but you have the terpenoid or isoprenoids groups of compounds which make up voltaile oils. The more pungent leaves will have oil glands - so taxonomic groupings will share this character.
e.g Rutaceae, Lamiaceae (APG 3 - including Myoproaceae), Myrtaceae..


The isoprenoid biosynthetic pathway goes back to bacteria (used to make carotenoids), and volatile terpenoids occur in bunches of critters like conifers and angiosperms. Being a complicated biosnthetic pathway, there will be pathways regulated by genes which control how the basic isoprenoid / terpenoid chemical skeleton is modified by chemical reactions / metabolised.

Citronellal, citronal, limonene etc.. are isoprenoid products which occur in range of families (like myrtaceae, rutaceae) and which share same biosynthetic pathway to product these metablites.

As for terpenoid function - hypotheses include excess carbon release as byproduct of photosynthetic, for thermoregulation, herbviory deterrence, intermediates for producing pigments, and in fruits and flowers - for frugivore/pollinator attraction.

http://www.plantphysiology.org/content/135/4/1893.full

http://www.springerlink.com/content/vr607513772457g7/

http://www.sciencedirect.com/science...63782711000476

I'll note there are a number of esenetial oils which account for lemony scents - (citronal, citronellal, can't remember the others)..

and there's eugenol..

http://en.wikipedia.org/wiki/Eugenol


What you need is a good review paper(s) for isoprenoid biosynthetic pathways, their chemotaxonomic significance and mapping biochemical pathways and regulatory genes on a large phylogeny of vascular plants or flowering plants...


but - I'm gonna watch the doco on the great dividing range

[imictiorume]

Thank you Morrie and Neomyrtus, a very informative explanation .

Has there been any research as to why these plants smell this way??

Is it to make them more attractive to certain insects for pollination purposes maybe ??

To eat there fruit and disperse seeds etc,. ??

Or to discourage the plants from being eaten at all ??

Think it's time I did a bit more research??

Night folks.

Cheers.

[awagsFare]

and there's eugenol..

But we won't mention anything that might remind us of the dentist, when we are about to have dinner.

[GeraldCortis]

thanks muchly neomyrtus.

[GeraldCortis]

Thank you Morrie and Neomyrtus, a very informative explanation .

Has there been any research as to why these plants smell this way??

Is it to make them more attractive to certain insects for pollination purposes maybe ??

To eat there fruit and disperse seeds etc,. ??

Or to discourage the plants from being eaten at all ??

Think it's time I did a bit more research??

Night folks.

Cheers.

Yes.. I would suspect all these things and more besides..

[StitsVobsaith]

Thanks everyone who's posted, made this a far more informative thread than what I thought would come of it (was only a simple question/thought that popped into my head briefly whist I was raking my lawn of leaves and bits of lemon thyme). Smelt very nice too.

Reading the answers morrie and neomyrtus have provided make me realise how little I know about chemistry/biochemistry (yes morrie, I have the book you sent me and have read it partially, but still struggle with a lot (most) of this stuff). Think I might have to see what's available on the web in the way of really basic introductory stuff (doing only high-school science and then never really needing to use much of it for most of my life...).

[phinno13]

Personally I loooove the smell of lemon verbena. I don't think lemon balm is as nice, although it is lemony. I suspect there is an emotional response in that as my great aunt had the lemon verbena and when I was a child she was the only one who had those cottagey plants. They were not in vogue then.

This also brings to mind the smell of bluegums. So many people tend to say they smell of cat's piss. I don't get that smell at all. They just smell eucalyptusy to me. Strongly. I love mowing through the caps off the flowers when the trees in the backyard are in flower. I also like mowing most euc leaves, but the lemon scented gum is rather nice (mowed some of that with the mulch mower yesterday.....mmmmmmm).

I think I have quite a good sense of smell and I link memories to smells.

There are some things I don't like the smell of particularly, but not too many. The main one would be the leaves of the tamarillo. They stink!!! I also grow a herb my great aunt used to grow that she called Balm of Gilead.

http://www.henriettesherbal.com/pict...ariensis-1.htm

I like the smell, but some of the herb books suggest blokes like it and women don't. It's rather medicinal.

Well, now that I've waylaid things here, I want to know how to say Gilead. My mother's family always said gill-eed. A religious friend of mine says it is gill-ee-ad.

[Butiqueso]

It was always gill-ee-ad that I heard. but no scholarship in my family to base it on just local custom.
And Paul Robeson record

[Gorlummm]

*looks like a good thread for my question*
my son loaned me a book on curry cooking
some call for kaffir lime leaves
Q - could you just use a woolies lime rind or similar?
what is the difference between the leaves and the rind, and what is the difference between a regular lime and a kaffir lime?

[Butiqueso]

worth a thread purps. no idea though myself

[awagsFare]

*looks like a good thread for my question*
my son loaned me a book on curry cooking
some call for kaffir lime leaves
Q - could you just use a woolies lime rind or similar?
what is the difference between the leaves and the rind, and what is the difference between a regular lime and a kaffir lime?

I don't think that woolies lemon rind or similar would do the trick. Kaffir lime leaves have a very intense flavour. I get mine fresh from a local stall and when I use them, they really pack a punch. Since the plant grows here in SW WA, I can only imagine it grows in Tasmania and you should be able to source it there with a bit of hunting.

As to the difference in the species, I will leave that to others more knowlegable on such matters.

[educationonlines]

I'm glad that folks inevitably got onto the terpenoids. They're sheer chemical magic! All built up from a 5-carbon isoprene precursor - which itself comes from 2-carbon acetate - and of course, they all come form CO2! Enzymes control the lot.

[GeraldCortis]

*looks like a good thread for my question*
my son loaned me a book on curry cooking
some call for kaffir lime leaves
Q - could you just use a woolies lime rind or similar?
what is the difference between the leaves and the rind, and what is the difference between a regular lime and a kaffir lime?

The leaves of the Kaffir lime are an essential ingredient of many Thai recipes, including green curries, fish dishes and soups. The flesh of the fruit is usually thrown away, but the rind and zest is sometimes used. from: Burkes backyard-limes

With Tahitian(Persian) limes you may use the fruit green but preferably wait until they turn yellow. This species is mainly used for the juice(when ripe) and the zest from the rind(when green)

more on limes

[Effopsytupt]

Nicotiana has really stinky leaves. Cistus leaves have their own smell. The long leaf bundy box, E goniocalyx, really stinks when cut by a chainsaw.

[GeraldCortis]

A a propagator of plants.. I find that wattles really pong.. particularly if you disturb the roots.