Cloud Jungle Epiphytes|
From: aroid-l-bounces at gizmoworks.com [mailto:aroid-l-bounces at gizmoworks.com]
On Behalf Of ExoticRainforest
Sent: Tuesday, May 20, 2008 9:10 AM
To: Discussion of aroids
Subject: [Aroid-l] Philodendrons produce infrared light???
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to the fellow in London who originally made the post on UBC asking if he had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!
Chris, it appears possible you may have opened a new door in understanding
more of the pollination of Philodendron species. Whether you have simply
made an observation or a discovery is yet to be determined and I am
certainly not qualified to comment. I am now receiving a stream of mail
from researchers and skilled aroid experts who find your observations of
The one thing that would have been of greatest benefit would have been that
you had a better understanding of what you were observing at the time you
took your measurements. By understanding what was happening you would have
been better able to more accurately record information at the critical
phases during anthesis.
Now, let me state I am not an expert in this field. I just study it a great
deal and spend a lot of time discussing information with people who are
experts. Don't take everything I write here as science fact, just take it
as a basis for your own studies. Since you are apparently relatively close
to the Royal Botanic Garden Kew in London I would strongly recommend you
attempt to seek an appointment with Dr. Simon Mayo who is one of the world's
top aroid botanists and experts in Philodendron species, especially those
from Brazil. Your specimen of Philodendron bippidifidum is a Brazilizian
Philodendron species. Simon is one of the authors of a scientific text
entitled The Genera of Araceae. That text is quite costly, around $180 per
copy U.S., but if you are interested in persuing this endeavor you will
learn a great deal about pollination within that text written by Simon, J.
Bogner and Pete Boyce. It is the single most comprehensive such text
available. In addition, secure a copy of Deni Bown's text, Aroids, Plants
of the Arum Family. This book is relatively inexpensive and available from
Amazon.com. Deni's book is jam packed with aroid information with more than
a single discussion of the processes you observed.
I have several follow ups which I will be posting but for now I'd like to
give you some "food for thought" regarding what you observed.
Aroids are pollinated by insect species, often very specific "assigned"
species. The vast majority of Philodendron are often visited by the male
of a beetle species found within the genus Neelia, although these beetles do
not appear to feed nor mate on the inflorescence. It appears only larger
beetles actually do the work of pollination. The pollinators appear to be
members of subfamily Dynastinae in the family Scarabaeidae. Many belong to
the genus Cyclocephala and have been recorded as pollinators of Philodendron
and other aroid genera. Some of these beetles are not particularly species
specific and visit more than a single Philodendron species, however it is
surmised the height of the plant may be a particular attractant to
individual beetles thus causing them not to cross pollinate other
Philodendron. Those beetles are generally drawn to the Philodendron
inflorescence in the late day or at dusk and are apparently attracted by a
combination of pheromones (scent) and a source of food and shelter which is
composed at least in part of an oil produced on the staminate flowers
containing lipids along with the enclosure of the spathe. Shelter may play
a part since the male often brings along his mate in order to breed at the
Some Philodendron species have sweet smelling pheromones while others show
no noticeable aroma. The one you observed, Philodendron bipennidifidum,
appears to have been attractively scented. This aroma is produced by the
sterile male flowers on the inflorescence which are attempting to entice a
pollinator, and to the male of that insect species that scent may be similar
to the same pheromone that attracts him to a mate when she is ready to be
impregnated. This point is not factually certain within Philodendron.
Anthesis is composed of two primary stages, female anthesis at which time
the pollinator is attracted and male anthesis during which time pollen is
produced to be carried to another plant. Some species are capable of self
pollination, but not all. And as you will read later, a very unusual but
common chemical source may also help to prevent self pollination.
During anthesis (both female and male) the open spathe of the Philodendron
provides space for protection and often entices these beetles to use that
area for feeding along with a place to safely copulate. The plant provides
a source of nutrient rich lipids which is an excellent food source for the
beetles, but the plant also benefits. It is not uncommon for the beetles to
spend the night within the spathe and spadix of the host Philodendron and
they frequently mate during this period. So why do they spend the night?
Thermogenisis! Quite simply, the spadix can warm enough to be noticeable to
the touch and for the insects that may be tired from traveling long
distances to perform their required tasks this additional source of heat in
the rain forest creates a microclimate and may actually increase their
metabolism and encourage them to explore all portions of the spathe and
spadix. Quite simply, a microclimatic zone of warmth is now being generated
within the spathe that offers both comfort and protection along with food.
This feature alone may increase the chance of self pollination within the
specimen, but another may inhibit the same.
The thermogenesis produced by the plant during anthesis, which is simply a
natural heat produced by many living beings, appears to stimulate the
beetles into this period of copulation. Of major interest, even though the
effects of thermogenesis have been observed for over 200 years, not until
relatively recently did anyone know the cause. So what is the chemical
cause? Salicylic acid, the same compound used to manufacture aspirin! The
salicylic acid begins not only the heating process but also the production
of the pheromones (scent). This unique process is not limited to Aracea
(aroids) but is also found in other plant genera. Read Deni Bown's book for
a more complete explanation. Of interest, salicylic acid may also help to
prevent self pollination which is an interesting contradiction in and of
The thermogenesis (thermo genesis. "Heat Birth" or heat production) caused
by the salicylic acid appears to be one of the stimulators to cause the
beetles to be active and as a result to both feed and copulate. It is known
the rate of thermogenesis (heat rise) is sometimes dramatic. And that may
be what you observed with your IR thermometer. However, thermogenesis does
not produce a consistent temperature since the highest temperatures appear
to last only 20 to 40 minutes. In fact, it may be the visit of the beetles
that contributes to the effect botanists know as thermogenisis.
I'm sure you are now questioning why you didn't see any beetles, and that
raises a new group of questions since scientists have known for a long time
they don't need to be present for thermogenisis to manifest itself. But the
presence of beetles does appear to increase the temperature produced by the
event. The temperature increase appears to increase the amount of pheromone
being exuded by the tiny flowers, thus the strength of the pollinator
attractant. Up to 200 beetles at a single time have been observed on a
single inflorescence during anthesis! However, the normal number is closer
to 5 to 10. Researchers have noted the highest temperatures appear to occur
during the period when the highest number of beetles are present. However,
the exact role of thermogenesis is still not well understood and your
observations "may" have opened the door for additional research. Right now,
no one appears to know if research on infrared heat in relationship to an
attractant role is being done.
You just observed both female and male anthesis without fully understanding
what you were watching. The first stage is when the female flowers are
ready to be pollinated and the production of the attractant pheromone along
with thermogenisis begins. Female anthesis in Philodendron can last
approximately 2 days. That stage is followed often a day or so later by
male anthesis which is the point when pollen is produced. The pollen often
appears to be a stringy substance as you observed. The beetles often visit
a separate inflorescence in the male stage of anthesis prior to visiting an
inflorescence beginning female anthesis and thus collect pollen on their
bodies and transfer that pollen from one healthy specimen to another in need
of pollination. All of this is within Nature's ingenious design to keep the
ecosystem strong and healthy.
Now, here are the questions at hand. Is the infrared heat you observed
directly related to thermogenesis or something entirely different? Does the
infrared heat have any impact as an attractant on the assigned beetle
pollinator? I really cannot offer an opinion although it certainly appears
plausible. I asked several interested experts as explained in another post
and these interesting responses I received from D. Christopher Rogers,
Senior Invertebrate Ecologist/Taxonomist, EcoAnalysts, Inc. stood out,
"Infrared thermometer works by detecting radiation in the IR spectrum. IR
radiation is emitted by all objects depending on their temperature. IR is a
color 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 color 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
color 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 temperature
is to calibrate itself.
So, metabolic reactions will generate heat, which is measurable in the IR
spectrum. One of my favorite aroids 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 the deathly perfumes) it seems that the ability would be found
residing in other aroids as well."
Christopher then continues responding to the question of the possibility
infrared is involved in the process of anthesis as an attractant, "YES!!!
Many insects respond to infrared. This is why the moth (and some many other
insects) come to the flame (porch light, candle, mercury vapor bug
collecting light, et cetera). One paper I remember reading discussed how
certain moths produce IR. The female corn ear worm rubs her body building up
a static electricity charge through friction. She releases her pheromones in
a cloud and then discharges the static charge into the cloud giving an IR
flash, attracting mates (and a few predators and parasites!!) towards her.
So again, plants could easily be using IR as well as pheromonal tricks to
Mosquitoes do a similar thing; when I was working for the State Health
Department on mosquito borne diseases, I used a CDC trap. This trap is a
bucket filled with dry ice (carbon dioxide) over a very small ?wheat grain?
light. Female biting mosquitoes follow the CO2 (assuming it to be exhaled
breath) to find a good host, but then focus on the IR glow of the tiny light
as the exact source, after following the CO2 trail. When they approached the
light, they were then sucked into a chamber by a small fan."
So, now that we can establish the fact infrared can act as an attractant we
are still left to ponder whether or not it will act as an attractant to the
specific beetle species involved with Philodendron. I'm not sure if anyone
knows the answer. But here is some conjecture that is being batted around
as a result of your post. The current questions are asking if it could be
possible if the initial attractant is the pheromone which acts more like a
long range invitation and "aims" the beetles toward the plant that is now
nearing female anthesis? It is known from the study of orchids that many of
these assigned insects can sense a single molecule of the pheromone from up
to one mile away. But that leads to a another question. Is it the
thermogenesis that is the final attractant attracting the beetle and his
mate to a source of food? Or is it possible the infrared heat also severs
in addition to the pheromone attractant. In other words, the infrared heat
could possibly act as a "neon sign" which is basically blinking "Eat Here,
Sleep Here, Have Sex Here"! Is that possible? I just do not know! But you
have posed some interesting thought.
Again, I strongly recommend you consider buying and reading the text by Dr.
Mayo, J. Bogner and Pete Boyce as well as Deni Bown's text. These three
scientists are among the best in the world when it comes to aroid species.
Deni is an accomplished writer but the facts posed in her text are well
researched. Additional great information can be found in the Annals of the
Missouri Botanical Garden 1997, volume 84, #3 by Dr. Thomas B. Croat. Pose
your theories to Simon if you can manage an appointment at the Kew. In the
meantime, I can assure you there are now some in the United States who have
shown interest. Will it prove anything to which you can claim credit? I
have no idea. I'm just a writer/photographer who loves to study aroid
Just one additional note. The information presented here was gathered from
the International Aroid Society website HYPERLINK
"http://www.aroid.org/"http://www.aroid.org/ as well as from the texts
mentioned. Input on this was given by aroid experts Julius Boos and Leland
Miyano in addition to the named sources. If you are truly interested in
learning more about your aroid specimen I would urge you to consider joining
the IAS. You can do so by clicking on the link above. The $20 per year you
will spend on membership will come back to you many times in journals and
information alone. You will quickly learn many of the members of the
International Aroid Society are extremely knowledgeable about the plants
they grow and they are quite willing to share information.
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