how do orchids control when they release fragrance?

[inkeys]

i have a few fragranced orchids and i noticed they only produce fragrance during the day and some how stop producing fragrance in the evening. how does the plant do this?

[dabblin-n-orchids]

those that are fragrant during the day and not at night generally produce volatile fragrance compounds (mostly esters) that when heated by for example the sun are vaporized and thus become airborne and detectible. when the temperature drops at night the compounds are not released.
as for night fragrant species. i would speculate that it is linked to the light dark cycles of plant metabolism and production of fragrant compounds only occurs in the absence of light. but i can't be sure. maybe someone else will chime in on the night fragrance issue. my dear friend google scholar isn't much help tonight either.

[orchidsarefun]

its all to do with insect pollinators and when they are most active - different times of the day or night. Orchids evolved all sorts of mechanisms/attractants to entice pollinators ( birds, insects, animals etc ) and fragrance is just one on the list.
Unfortunately man and manual hybridisation can interfere with this natural process - for example breeding out fragrance in favour of longer-lasting flowers.

[Wrebbitrocks]

ive noticed that too. in fact just today i wouldve written a post. some of my orchids only produce smell from sometime in the morning til 5pm sharp and literally just stop. its very odd. like they know the time or something. ive also noticed that almost all my orchids are fragrant when they werent fragrant when i bought them. this arrangment i put together didnt smell when i made it but right now its just filling the living room. my phals smell like lemon and dens like cinnamon...

[DavidCampen]

"Flowers give off their scent without any visible external stimulus. They control the scent release by an internal biological clock which is particular to each species. Environmental factors, including light intensity, day-night cycle and temperature, act as triggering or inhibiting impulses ..."
The Scent of Orchids, Roman Kaiser,1993, Elsevier, Amsterdam, ISBN 0-444-89841-7

[bballr4567]

I exprimented today with my Onc. Sherry Baby and changed the time my growth light was on. I changed it by two hours and sure enough the scent lasted much longer. As soon as the light shut off the scent went away in about 10 minutes.

[inkeys]

thank you all for answering! this is something i have always found so interesting about orchids because i would say safely, none of my other flowering plants do this. if they have fragrance, the fragrance is still there whether i sniff at 7am or 10 pm.

David your reply gave us the answer. i knew it had to do with pollinators and when the plant wanted to attract said pollinators but wasn't sure how the plant could actually control when it was scented; so interesting!

[Cattleya17]

So glad I found this post! I have wondered the same thing! Orchids are highly designed plants!! Question then. Why are some orchids fragrant and others not. Like say Phalaenopsis species are generally fragrant while Phragmipedium orchids are not. Is it that its fragrant but just not detectable to humans and only it's pollinator or are they just not fragrant?

Another thing that is quite interesting is that if you cut a fragrant orchid flower off its stem it immediately stops being fragrant or very quickly after.

[orchidsarefun]

an interesting article

Timber Press is a Portland

[nenella]

Very Interesting,Thanks for posting!