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  Philodendrons produce infrared light???
From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.19 at 20:54:19(17583)
There is a guy on UBC which is one of the sites I often answer questions about aroids insisting his Philodendron bipennidifidum is producing infrared light as a result of the spadix going through male and female anthesis. I've tried to explain the process as I've learned it from Dr. Croat and Julius including insect pollinators and how they are attracted to the plant as a result of pheromones. I now am receiving private male from others saying they think he is onto something. It is obvious from his "strange science" he knows nothing about aroids. He had no idea what pollen even was, yet he described it as a purely personal observation. His theory is the heat produced by the spadix is a result of infrared light and he appears to have no understanding of thermogenesis. Will any of you please let me know if such a thing is even possible?

I've read of nothing close to this in any of the published material in my library. I am checking Simon Mayo, J. Bogner and Pete Boyce's book right now, so if any of you know of something I don't know, please put me on the right track.

And by the way, Julius, you sent me a great explanation of how Philodendron species reproduce. I can't find that anywhere! I would have sworn I added it to my website but can't find it now! If you have
that at hand, please send it to me and also publish it here.

Steve Lucas

From: bstover at uark.edu (Bryan J. Stover) on 2008.05.19 at 22:07:06(17585)
Steve, of the wonder kidney, wrote:

"And by the way, Julius, you sent me a great explanation of how Philodendron species reproduce. I can't find that anywhere! I would have sworn I added it to my website but can't find it now! If you have that at hand, please send it to me and also publish it here."

Second the "publish it here" motion. Thanks!

From: Thomas.Croat at mobot.org (Tom Croat) on 2008.05.19 at 22:44:59(17587)
Dear Steve:

There is a rather complete discussion of pollination in
Philodendron in my revision of Philodendron for Central America.


From: ted.held at us.henkel.com (ted.held at us.henkel.com) on 2008.05.20 at 12:18:42(17589)

I expect that what is being described is infrared light radiating from
internally-produced heat via thermogenesis. Thermogenesis will happen in
the dark. Warm bodies radiate infrared. You, sitting at your computer
screen, are generating infrared just sitting there and being alive. That's
how you feel warm when there's a fire across the room. The amount of heat
emitted by a body depends on its temperature and will radiate energy even
when quite cold, although it is not as easy to detect. The earth radiates
stupendous amounts of heat into space all the time.

Yes, an infrared camera will pick up a glow from an aroid "in heat".


From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.20 at 13:09:31(17590)
Since Saturday of this past week, Julius Boos, Leland Miyano, Christopher Rogers and I have been discussing the possibility (probability) that infrared may be involved in the process of thermogenesis and pollinator attractaction within aroids. It appears to us, and Christopher is the only trained scientist among us, this concept is very likely possible!

I personally find it interesting that I've not read of any research within the aroid community on this concept. With the help of all of these, as well as by doing some research on the IAS website and by reading information within Simon Mayo, J. Bogner, and Pete Boyce's great text on Araceae as well Dr. Croat's journals along with Deni Bown's book, I have prepared a response to the fellow in London who originally made the post on UBC asking if he had actually observed "infrared light" involved in the anthesis of his Philodendron bipennidifidum. Now is where I really need the input of all you honest to goodness aroid scientists out there on this forum!!

The University of British Colombia plant discussion website has been offline due to a server failure since Sunday. As a result, this has not been posted. I would very much like input from any of the world class aroid botanists who read this forum. Tell me if I have my facts right and if I got something wrong, what do I do to correct it? I'd personally really like to see this discussion continue on the Aroid l forum!

If this is possible, and it certainly appears it may be a part of thermogenesis as well as an attractant feature for the pollination of aroid species, I'd love to learn more. I'm not a scientist and what I've written is based solely on what I can read along with the input of Christopher, Julius and Leland. But if this idea has merit, it would certainly appear more research would be useful to our community.

Now, this is my post which will be made once the UBC server is back online. If you see errors or anything that needs to be addressed, please point it out! The post is addressed to the fellow who asked the original questions.

One point if I may addressed solely to the readers of this forum. I know a lot of people are relatively new on Aroid l since I often see new names asking questions or responding to ones posed by others. Our community is composed of people who have an interest in aroids and as such should have an interest in the International Aroid Society. I'm going to steal Julius' podium and suggest that if you have not taken the time to join IAS, please do so right now! The $20 per year you will spend will come back to you many more times than you realize! And if you are not using the IAS website to answer your own questions about aroids, you have missed one incredible source! Please consider joining right now!


Steve Lucas

From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.20 at 17:39:35(17591)
And I'm about to read it again Tom! Although I feel a great deal better I still tire easily. But this subject fascinates me so I'll be reading your work. Again!


From: hermine at endangeredspecies.com (hermine) on 2008.05.20 at 17:52:49(17592)
>Yes, an infrared camera will pick up a glow from an aroid "in heat".

and really, who wouldn't.

It is an interesting IDEA. even if the fellow did not know what was
pollen. sometimes physicists can be remarkably dense about plain old
biology us dirt farmers take for granted. I only recently found out
that certain flowers which to humans look WHITE, appear to be like a
Stanley Kubrik on LSD colour fantasy beyond our ability to perceive
the visible spectrum, if one is a bug or other pollinating agent.
Moth, perhaps, I dunno. Anyway, even as dogs hear notes we do not,
and scream about it, some creatures see incredible colours where we
see only white. poor blind things that we are, and to a dog, deaf,
and to a bloodhound, we are olfactorilly challenged. I have trouble
with that word, I am trying to make it look right, and the spell
checker has gone MAD.
anyway, you probably all knew this long before me.


From: gibernau at cict.fr (Marc Gibernau) on 2008.05.21 at 07:48:07(17598)
Dear All,

I have studied, with Denis Barab? et Roger Seymour, thermogenesis in many
aroids and particularly Philodendron.

The thermogenic process, the heating, is due to a particular respiration of
the cells of the spadix which converts the biological energy into heat.
Increasing the temperature of a body leads to increase its emission in the
infrared wave lengths (see picture on page 4 of the attached document).

In conclusion, yes thermogenic flowers/inflorescences can be detected in
infrared when heating. Heating is ten cause of the infrared radiations and
not the contrary.

About the pollination of Philodendron on the IAS web site you have several
pages dedicated to the pollination ecology of aroids and one particularly
on Philodendron :

I hope my explanations are clear.

All the best,


From: harrywitmore at witmore.net (Harry Witmore) on 2008.05.21 at 12:13:51(17599)
Hasn't there been research about this associated with Skunk Cabbage
(Symplocarpus foetidus)?

Harry Witmore

From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.21 at 21:52:19(17601)
Apparently Harry. I just never ran across it until a private message made me at least aware of it. If anyone knows where to find that information, please post it!

Steve Lucas

From: gibernau at cict.fr (Marc Gibernau) on 2008.05.22 at 09:28:42(17604)
Hello Harry et other aroiders,

Many papers have studied the thermogenesis in the Skunk Cabbage but none
related to infrared, but here again IR as heat source is improbable and
likely a consequence of thermogenesis.

All the best,


From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.23 at 18:13:31(17605)
This morning Julius and I received a private response from Marc Gibernau in regard to the observation originally proposed by British engineer Chris Rennie on the University of British Colombia (UBC) plant discussion forum about "infrared light" and a spadix in anthesis. You can read Marc's original response to Aroid l just below this message. The possibility of whether infrared heat may or may not additionally serve to propel thermogenic attractants to aroid pollinators is obviously incomplete. As to whether or not infrared (IR) acts as any sort of homing device for the beetle pollinators of Philodendron or other aroid species, at least research is apparently being done. And there is a possibility it may assist!

It is known that many insects can and do use IR to find both light and prey. A private message from entomologist Christopher Rogers explains more and I've included that in this post. But can these beetles which are the natural pollinators of many aroids be attracted to the spadix of an inflorescence entering anthesis as a result of infrared heat as well? To a beetle does the "glowing" spadix appear as a beacon in the night with a sign yelling "eat here, rest here, have sex here?". If you read my post on UBC to Chris which I also posted on Aroid l you will see I proposed the long range attractant may be the pheromone and a short range attractant could be the infrared heat. I have no idea if that is possible! But work is apparently being done to learn more.

This is the message from Marc this morning, "Yes heating inflorescences are spot visible in the IR up to 15 meters according to our IR camera. Some beetles (laying in burnt woods) are known to have IR receptors to localize the forest fires. I sent some Cyclocephala (Philodendron pollinators) in Germany for detecting IR receptors but the results were negative. But the fact is that IR attraction is possible, I will continue on this topic, particularly with a Brazilian student.

All the best,


There was some very interesting input from folks to this possible idea posted on UBC. I personally believe all of you aroid enthusiasts might find the discussion on the University of British Colombia plant forum at least of interest. If nothing else, you may learn something more about aroid pollination.: http://www.ubcbotanicalgarden.org/forums/showthread.php?t8988

But before you read the several pages of discussion in which I began more than dubiously and subsequently began to see new possibilities with the urging of Julius, Leland Miyano and Christopher Rogers, watch Chris's time lapse photos of his inflorescence at this link:
http://www.ubcbotanicalgarden.org/forums/showthread.php?t9167&highlight=time+lapse I think you'll find it fascinating how the inflorescence bobs and changes its position.

At least I now have a much better understanding of the process of thermogenesis,, pheromone attractants, aroid pollination and how insects "see" as a result of feedback from a bunch of you sent privately. My special thanks to Julius and Leland as well as Christopher Rogers who is a regular on Aroid l. Dr. Croat's journals are of special value to me and always provide great information.

This message was sent to Julius, Leland and myself by Christopher Rogers as a result of this discussion, "An infrared thermometer works by detecting radiation in the IR spectrum. IR radiation is emitted by all objects depending on their temperature. IR is a colour like any other part of the electromagnetic spectrum, just like visible light, but we just cannot see it, although many insects and crustaceans can, as well as some birds. (Just an aside: some raptors can see the urine tracks in infra red left by rodents (who just dribble wherever they go) and so know which areas to concentrate on for prey items). So, there is IR colour and also IR radiation emitted by all objects. The higher an object's temperature, the greater the object's IR radiation. The IR thermometer does not tell you the colour of an object, it tells you the heat it is radiating by a correction factor multiplied times the IR radiation. This is exactly how the IR camera and thermometer work. But it must know what the basic background temperat
ure is to calibrate itself.

So, metabolic reactions will generate heat, which is measurable in the IR spectrum. One of my favorite aroids (which bloomed wonderfully for me this year) is Helicodiceros muscivorus, the Dead Horse Arum. The cells in the spadix are packed with mitochondria, which are the cell powerhouses. As a result, they raise the temperature of the plant to a wonderful 98.6 degrees F when they are in bloom and producing their macabre odors. It seems to me that anthesis is probably very costly (in energy) to the plant. So, the mitochondria are working hard to move anthesis along, spending lots of energy, much of which is lost as heat, and therefore generating an increase in IR radiation. Since insects do cue in on pheromones and the IR discharge in those pheromones, it seems a very logical step for the plant to exploit in the attraction of pollinators. Obviously, since Helicodiceros, Amorphophallus and Typhonium all produce heat from the spadix appendix (possibly to volitalize scent molecules as well as to add allure to t
he deathly perfumes) it seems that the ability would be found residing in other aroids as well."

I see Aroid l as a place to learn, and not just about the basics. That's why I often ask crazy questions! I get great information from a bunch of you and as you likely realize I am constantly filled with aroid questions! Those of you who are new to Aroid l may not know that many of the world's best aroid botanists and experts are right here with us! They read these posts and often make comments, so the information you receive here (free) is very valuable.

A couple of suggestions if I may. There is an incredible body of literature available out there to all of us. Just about anything worth reading on aroids can be read on the IAS website or acquired through the International Aroid Society. Every one of you should own copies of Dr. Croat's journals on Anthurium and Philodendron species as well as his journal on Central American Philodendron. These are quite inexpensive and I guarantee I read something in one or more of those every day. Another text which is incredible is Simon Mayo, J. Bogner and Pete Boyce's The Genera of Araceae. That one is costly but worth every penny. And if you don't have Deni Bown's book Aroids, Plants of the Arum Family, order it today! I rhink the price is only around $20. I'm virtually certain Tricia Frank can provide any of these to you through IAS. Tricia, if you read this will you post a note and let everyone know what texts you have in stock?

You don't have to be an IAS member to buy them, but you should join if you are still on the fringes!

To all of you who have sent private messages, and there were a bunch, if you feel your material will continue this discussion and perhaps spur more research, please post those here! We mentioned earlier Julius' article on the pollination of aroids and that is almost complete. I have been doing an edit for Julius and once he approves the final version I will post it on my website. I'll post the link here at that time. If you have even considered attempting to hand pollinate an aroid you need to read this! Julius is brilliant and his facts very easy to understand! He explains about both bisexual and unisexual inflorescences and offers tips on how to do pollination when the necessary beetle is still thousands of miles away in a rain forest! Sorry, no inside secrets, just science fact.

Thanks again to all of you and keep the information coming!

Steve Lucas

From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.23 at 18:38:30(17606)
One thing I didn't make clear in this post that I should! Marc Gibernau is one of the top aroid pollination researchers in the world. If there is a possible connection between infrared and pollinator attractants, Marc is likely to be involved in learning about the processes involved.

Just another good reason you all should be proud to be a apart of Aroid l and the IAS!

Steve Lucas

From: hermine at endangeredspecies.com (hermine) on 2008.05.23 at 21:36:54(17607)
At 11:38 AM 5/23/2008, you wrote:
>One thing I didn't make clear in this post that I should! Marc
>Gibernau is one of the top aroid pollination researchers in the
>world. If there is a possible connection between infrared and
>pollinator attractants, Marc is likely to be involved in learning
>about the processes involved.
>Just another good reason you all should be proud to be a apart of
>Aroid l and the IAS!
>Steve Lucas

From: pjm at gol.com (Peter Matthews) on 2008.05.24 at 01:54:27(17608)
If infra-red radiation from the aroid spadix serves as an insect
attractant, it might be interesting (for researchers) to look at the
plant from different angles - from the side, from 45 degrees below and
above, and from directly overhead.

In the vertical direction, the radiation effect might be more
concentrated, and therefore visible to insects from a greater distance.

Perhaps even the angels are looking down.

Cheers, P.

From: Chris.Rennie at blueyonder.co.uk (Chris) on 2008.05.24 at 17:03:56(17610)
Absolutely agree!
The spathe and spadix on my philo so resemble a parabolic dish which is
why I would dearly love to get my hands on a thermal imaging camera
and produce a time lapse of the spadix heating. I suspect the spathe may
be infra red reflective?

Thread here: http://www.ubcbotanicalgarden.org/forums/showthread.php?t8988
See my post #13 about half way down the page.



From: leo at possi.org (Leo A. Martin) on 2008.05.25 at 01:17:22(17611)
Cycads bear cones, produce pheromones, often heat, and so far all the
known pollinators are weevils for the Americas and Africa, and thrips for

From: LLmen at wi.rr.com (Don Martinson) on 2008.05.25 at 18:45:23(17615)
It's hard to believe that there aren't some camera buffs out there willing
to experiment with some IR film. I realize that in this digital age, film
photography may seem passe and that IR film may not be the easiest to find.

However, there are (or at least were), several brands available brands

Kodak High Speed Infra-Red
Ilford SFX 200
Konica 750nm 120 Infra-red Film

My problem is a lack of potentially IR emitting inflorescences here in the
far north, but places like FL should be literally swarming with them.

A great potential Aroidiana article.

Don Martinson

From: Steve at ExoticRainforest.com (ExoticRainforest) on 2008.05.26 at 00:32:23(17622)
IR photography is highly specialized. Kodak used to sell a book but you can't use any ambient light which will affect your exposure.

Steve Lucas

From: gibernau at cict.fr (Marc Gibernau) on 2008.05.26 at 09:09:09(17624)
Dear Aroiders,

I'll not write a long e-mail because, as I wrote to some of you in private
messages, the research on this topic is in fact "very" recent even if the
idea is may be 20 years old.
Please find in attachment the figure of a recent paper written by Roger
Seymour (Univ. of Adelaide, Australia) and myself on the thermogenesis of
Philodendron melinonii.
The paper is a bit complicate but the this figure present a real picture
and the equivalent IR picture of the same inflorescence during
thermogenesis (heating phase).
Hence you can see the inflorescence like an insect could "see" it through
its IR receptors. Flashy!!! There is no question if the pollinating beetles
have IR receptors they can detect a heating inflorescence. The questions
now to study are:
Do Cyclocephala beetles have IR receptors ?
What are their sensibility & efficiency?
Are IR radiations used as a guide by Cyclocephala beetles to find the
inflorescences to visit or are odors sufficient ?

To finish, I would like to say that I have the honor to be the IAS speaker
during the Annual show next September, and that I'll pleased to tall you
some "nice "stories around thermogenesis and IR radiations.

All the best,


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