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Anthurium regale Linden
  Growth of an inflorescence   
Please note:  This page contains numerous photographic images. 
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                       Photos © 2006/2007 Steve Lucas

Anthurium regale Linden
 Growth of an inflorescence
 
Page 5 of 6
Includes Day 45 through Day 55

See Page 2 for the definitions of botanical terms used in this description.
This is Page 5.  Page one contains our observations regarding this species.  This is the fourth page showing photos of the growth of our Anthurium regale spathe and spadix.  The large number of photographs has made it almost impossible for those with a dial-up connection to from a single page.  If you found yourself on this page without reading the first four pages click below to go to either Page 1, Page 2,  Page 3, or Page 4:
 
Anthurium regale Page 1  To read our observations regarding this species click on this link
Anthurium regale spathe and spadix Page 6   Day 56 though latest images
 
 
 
Day 45:  We have 3 to 4 inches of snow today with more expected.  The only advantage is the snow acts to insulate the roof of the atrium thus raising the temperature to 63 degrees F inside.  Despite the fact I am using a professional flash unit photography is still difficult due to the extremely low light level in the atrium.  No evidence of pollen shedding can be observed but the stigmatic hair openings to the stigmas described earlier as "fuzzies" by Julius is evident all over the spadix.  The color of the spadix appears to be further lightening and is now a light yellow as opposed to the bright yellow of only a few days earlier.  I cannot observe any obvious stamens present.  The water droplets are all a result of the extremely high humidity within the building.
 
 
 
 
Day 46:  No evidence of stamens.  Only the damaged stigmas approximately 1/3rd of the way up the left side are apparent (see right photo). 
 
 
Day 47:  No evidence of stamens.  The damaged stigmas are visible near the top left of the first photo.  However, look at the top center perigone in the center of the center extreme photo.  Something appears to be sticking out of the stigma enough to cast a shadow to the bottom right.  When photographed from the side view to the right side of the spadix the same magnification shows far more darkened stigmas but nothing yellow or white in color emerging from the stigma.  Could the stamens be darker in color than expected?
 
 
Day 48:  Even at the highest possible magnification possible with my photographic equipment no stamens are visible.  I've attempted to photograph the spadix against both light and darker colors just in case the stamens are a darker color than expected.  Limitations in the depth of field of the lens makes it impossible to get all aspects of the spadix in perfect focus.  I estimate the center photograph to be between 8 and 9 times life size.  The extreme left photo shows the spadix approximately 1/3rd the way up on the left side.  The color of the spadix continues to turn lighter.
 
 
Day 49:  The spadix continues to lighten in color.  It is now almost white.  Despite examining the spadix with an 8X magnifying glass I cannot see any evidence of stamens.  The damaged stigmas are visible in the extreme right photograph and can also be seen in the first photograph.  Later in the day I received this observation from knowledgeable grower Michael Pascall in Australia, "re: lack of stamens on your regale , this may be one of the species that does not have exserted stamens , warocqueanum is similar." I sent an email to Dr. Croat checking into the possibility.  Tonight he forwarded this response, "Pictures 44–49 are the first that I have seen that really appear to be at anthesis.  I would not expect stamens until the stigmas have dried.  I notice that some of the stigmas appear to be turning black.  That would indicate that they are past anthesis.  Perhaps your flowers will still produce stamens."

 

Day 50:  Dr. Croat has prompted me often to try to observe and describe the scent.  Finally, today the spadix is fragrant.  Very fragrant!    The scent is similar to a light sweet perfume.  The spadix has now turned ivory, much lighter than 3 days ago, however stamens still cannot be observed.  The water droplets fall from the ceiling and are a result of high humidity in the atrium.  Once Dr. Croat reminded me, it is now obvious many of the stigmas have not yet dried.  Perhaps what we thought was the beginning of anthesis some weeks ago may have been a false alarm!   Or perhaps, anthesis is simply a slow process for this species.  The key may have been the color change.  When I informed Dr. Croat of the long awaited scent he responded, "I am glad to hear that the presence of seemingly receptive stigmas is associated with the presence of an aroma.  That is the normal pattern.  At what time of the day does the scent occur? The timing and duration of the scent?  This is perhaps the best indication of the actual timing of pollination. Some species have scent for only a short time, sometimes early in the morning. I know of a species that produces scent only between 11:00AM and 1:00 PM.  It just turns out that this is the time of day when the weather for pollination is best because it is often raining at other times."  In the case of this Anthurium regale spadix the scent was first noticed at approximately 11:00AM and again at 1:30PM.  Tomorrow I will check more often in an attempt to learn the exact times and duration.


 

Day 51:   The spadix continues to lighten to a light ivory coloration.  This morning I began the check for a scent at 7:30AM, none was apparent.  At 9:45AM the scent was very faint, and again at 10:30AM it could be noticed but was not as strong or sweet as midday yesterday.  By 11:00AM the scent was quite apparent and could be noticed a few feet away.  The fragrance remained strong until approximately 1:30PM when it began to fade.  By 3:00PM it was still evident, but faint and by 3:45 it had vanished.   It appears the fragrance is strongest for less than 4 hours.  No  stamens are yet obvious in the photos or with a strong magnifying glass.  I did observe approximately 1/2 up the left side of the spadix several stigmas were very darkened (see second extreme photo).  This morning Julius made this observation in an email addressed to both Dr. Croat and myself, "The fact that only now, at or near male anthesis, is a perfume-like fragrance detectable (at least to humans), begs the question as to exactly what is the fragrance or attractant might be at female anthesis that gets the pollinators to bring the pollen from another spadix, since we could not detect any fragrance when the spadix was going through a long female anthesis! I guess lots more research will be needed on little things like this!"  Often, during the night, I had been pondering the same question.  The fact is certain, more research by someone more qualified than myself will have to be done!  When I advised Dr. Croat of the short duration of the fragrance, at least for today, he responded with this comment regarding the limited duration, "Pulcache, where this species occurs might well have the same type of climate where it tends to be rainy early in the day, then the sun comes out later in the morning.  Of course in most of the tropics the late afternoon is often rainy as the atmospheric humidity builds up. That causes rain. Though I was there about 2:00-3:00 PM as I recall and it was not raining."  Perhaps the species is designed to "time" pollen production to avoid the rain which would wash it away.  Since stigmatic hairs which are simply trichomes designed to induce germination of the pollen grains are very evident, hopefully pollen will not be far behind.
 
Shortly after posting today's photograph I received the following email from Dr. Croat which was addressed to both Julius and myself, "Don’t be so sure that the plant went through a long female anthesis.  I did not spot the stigmatic hairs until the last series of images and perhaps it was not really ready for pollination. Perhaps Steve missed the time when it was becoming fragrant. Perhaps the window of stigma receptivity is rather narrow.  I think that he will learn more about this window by making frequent surveys now to determine if it is a broad or narrow window. I suppose that it is even possible that the window is narrower on the pistillate phase than on the staminate phase.  It seems to me that it would be an unusual species that was aromatic only during its staminate phase."  It is certainly possible that I missed intermediate events during this process.  I am not a scientist, have no formal training in technical plant observation, and this project was done solely for self- edification.  However, Dr. Croat made one additional comment which I hesitated to post.  I have elected to include it solely as an encouragement to others to undertake similar projects on this and other species.  Dr. Croat offered, " Steve, what you have done (are doing) has rarely been done for any species and it is quite informative. I think that if you can pin down the whole sequence it is worthy of publication.  More of this needs to be done with more species because we really are very ignorant of pollination biology for most Anthurium."  I am in hopes others will pick a favorite species and follow it through with daily photography, measurements, and notes.  You don't have to be a professional photographer to do what I am doing!  All you need is a good digital camera and a note pad.  Perhaps those of us who are simply plant collecting "nuts" can provide useful information to science.

By day 52 the new leaf has extended from 11 cm (4 5/16th inch) to 17cm (almost 6 3/4 inches).  In 9 days it has increased in length 6cm (approximately 2 3/8th inches).  All portions of the catyaphylls are now visible.

Day 52:  Several interesting observations were made today.  First, the fragrance is only faintly apparent at 11:30AM.  On both previous days it was very noticeable by 11:00AM.  The only difference today is the sun's intensity.  Both of the previous days were bright and sunny, today it is overcast.  Could A. regale be responding to the intensity of the light?  By 12:00 noon the scent was increasing in strength, but still not as strong as midday yesterday.  By 12:45PM the fragrance was slightly more fragrant but still not as intense as yesterday.  At 1:30PM the scent was again growing faint and by 2:45PM had again vanished.  Is the plant avoiding attempting to attract pollinators since low light levels may indicate it might rain?  I am simply speculating since the answers will be found by someone with more scientific expertise.

Second, the stigmatic hairs are visible near the bottom of the spadix.  However, approximately 1/3rd up the spadix (see second extreme photo), in the region where the stigmas are damaged, few stigmatic hairs can be observed?  Why?  The second extreme photo was taken at a 45 degree angle to the left of the view normally shown.  And still, no stamens can be observed.  The coloration of the entire spadix is now noticeably brighter, approaching white.  Is the "white" coloration the actual visual key to the start of male anthesis and the production of stamens followed by pollen?

After reading my questions regarding the lack of and/or reduction of scent today in relation to the sunlight, as well as my comments on the stigmatic hairs, Dr. Croat had this response, "I do think that the sun might well have an effect on the production of the pharamone (scent) and it may not have anything to say about whether the climate might produce rain.  The stigmatic hairs should not be more receptive at the base of the spadix than at the middle except in a few rare cases where the lowermost flowers are not the first to emerge.  It is interesting that you still have no stamens developing. I have seen this happen before where stamens never emerge and I can't explain it.  I sometimes wonder if some species are not becoming dioecious, ie. producing male and female plants. It has never been proven to happen in Anthurium but in Arisaema we do know that it can happen."

In regard to my possible misreading of the timing of female anthesis, Julius wrote an interesting note to both Dr. Croat and myself this morning (February 8, 2007).   In it he said, "This whole exercise by Steve has been most interesting, and a lot based on speculation!   I too can not be absolutely certain of when or even if the female anthesis began.  But based on past experiences, the stigmas were dry during development of the infloresence and the opening, then reflexing of the spathe, then the drops of liquid began appearing on their tips (I assumed that this signaled female anthesis), this liquid then dried up, and at that
point you were able to observe the stigmatic hairs (as there was no longer any liquid on their tips, the color changes began around this point??), and only then did Steve detect the fragrance, so I assumed the fragrance was being produced at or near the start of male anthesis."  Julius is far more experienced in the observation of anthurium reproduction behavior than I, but it appears we may have been fooled by the behavior, or the misinterpretation of the behavior, of Anthurium regale.   Obviously, I still have a lot to learn!  Perhaps all of us have a lot to learn!

Day 53:  The sky is again overcast.  And again, apparently responding to the low light level, the spadix was slow to  produce pheromones (scent).  The scent did not begin to appear until almost 12:00 noon and did not become truly apparent until almost 1:00 PM.  At 1:30 PM the fragrance was still quite vague and by 2:15 PM was hardly noticeable.  When examining the photographs a puzzling observation became apparent.  A few "wet" spots were visible on portions of the spadix but did not appear to be water droplets from the ceiling.  When you look at the center photograph, lower right, you'll see moisture.  Tiny droplets can be seen at other places on the spadix and were much smaller than on previous days when water droplets had fallen from the ceiling.  As a result I elected to photograph the spadix from the right side.  No major water droplets were visible.  Instead, there are very tiny drops of moisture beneath several perigones. 

If you have been following this discussion you are aware I, along with several observers, felt female anthesis was completed several weeks ago.  But male anthesis has not appeared to begin.   Why?  We have not been able to observe any stamens appearing from the center of the stigmas.  Why?  Is this one of the species that does not produce obvious stamens?  Dr. Croat has expressed the opinion anthesis may have only recently begun.  Are these droplets a result of the female anthesis Julius explained would eventually begin and I assumed had already happened?  Are we still days away from male anthesis?  Another interesting observation that caught my attention.... the stigmatic hairs can be seen at least half way up the spadix, yesterday they were visible only part of the way up.  They are quite visible in both extreme photographs.  Honestly, I don't know for certain what is happening!  I'm just a curious untrained observer with camera in hand and more questions than answers.  But as I commented yesterday, perhaps we still have a great deal more to learn about this species.  And for those of you reaching for a dictionary here is the definition of the word you are about to look up: Senescence (si-NEH-suhnts):  Aging, the state of being old; the process of growing old.
 


Day 54:  It is again very overcast.  And, as a result, the spadix did not begin to produce any fragrance until almost 1:00PM.  At 11:30AM the upper set of photographs were produced.  No stamens are visible.  But look at the ends of several stigmas, they're wet.  It occurred to me the stamens may not be extended unless the pheromone was present.  The fragrance did not become evident until almost 1:00PM  and by 1:30PM was very evident despite the fact the sun is not out and there is a heavy cloud cover.  I then repeated the photographic process.  In the lower set of photographs you are looking at approximately the same area, the 1:30PM second photo set is simply a greater magnification, and the last photo is approximately a 10X magnification.  The moisture on the tips has vanished and/or run downward.  On the second extreme photo you can see where it appears to have run downward from two stigmas.  And if you compare the Day 54 to the Day 53 photographs you will see the stigmas are substantially darkened.  What does this indicate?  I don't know other than female anthesis appears to have long since passed! 
 
By 3:00PM the fragrance was quite faint.
 
When asked about today's observations Dr. Croat responded, "It is now apparent that some of the stigmas are past anthesis and it is interesting that you are still getting the aroma.  It is going to have to produce stamens soon or it may lose the pharamone that attracts the pollinators to the pollen."
 
 
Day 55:  It is again extremely overcast.  Today at 10:30AM no scent was apparent.  At approximately 12:00 noon the scent was noticeable and by 1:00PM was strongly evident.  But by 3:00PM it had again vanished.  The duration appears to be shorter which I am curious is a result of the lack of sunshine.  Stamens could not be seen on either the front or right side of the spadix although a very few stigmas appeared to be holding moisture.  Virtually all the stigmas have now darkened.
 
 
Day 56:  WE HAVE STAMENS  AND POLLEN!
 
 
 
 
 


 
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