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Anthurium regale Linden
 Growth of an inflorescence   
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                       Photos 2006/2007 Steve Lucas

Anthurium regale Linden
Growth of an inflorescence
Page 4 of 6
Includes Day 32 through Day 44

See Page 2 for the definitions of botanical terms used in this description.

This is Page 4.  Page one contains our observations regarding this species.  This is the third 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 three pages click below to go to either Page 1, Page 2, or Page 3:
Anthurium regale Page 1  To read our observations regarding this species click on this link
Anthurium regale spathe and spadix Page 6  Day 56 through the latest image

Anthurium regale spadix Day 32
Day 32:  It appears female anthesis is either at or near completion.  If you have been following my exchanges with Dr. Tom Croat on the previous pages you will have read where he prompts me to observe for a "scent" on the spadix.  As of today, still no scent can be detected.  Yesterday I proposed this question to Dr. Croat:  "Anthurium regale is said to be rare in nature yet it can become an enormous plant and the spadix is larger than many aroids I have in my collection.  It is obviously capable of producing a substantial number of seeds.  If anthuriums normally produce a scent in the nectar on their spadix when ready to be pollinated, which attracts insects to inspect these sugary liquids, why is mine not producing a scent?   Since mine has produced no scent after 31 days (I can't smell it, my wife Janice can't smell it, and Steve Marak can't smell it) and I can clearly see the exudate in the Day 30 photos, is it possibly trying to attract a pollinator that is not common or is unusual?  When tasted the exudate is bitter sweet instead of sweet.  I could taste what I suspect is the oxalate crystals in the liquid.  That made me wonder if  the plant attracts some very limited group of pollinators that enjoy this bitter sweet liquid.  But since the number of pollinators it attracts may be small it thus produces only a limited supply of pollinated seeds.   Thus the plant remains less common in nature.  I realize I have only experienced one spadix on this species and something else may be unusual or missing.  But now I'll be checking for this the next time I get a spadix on the plant.  I also now have a second plant of reasonable size which should produce a spadix within 8 to 12 months.  Is this theory possible?" 

Today Dr. Croat responded, "Since we know so little about the pollination biology of Anthurium I suspect nearly anything is possible.  I am surprised that your nectar was not sugary but that is interesting.   You should write up your observation for publication in the Newsletter or in Aroideana depending on how convincing a story you can tell. You probably know more about this species now than anyone else.  Could you make some measurements on your spathe and spadix.  We will eventually need a complete description of that species as well, even though it is not from Ecuador." 

I make absolutely no claim to knowing very much about this species.  I began this project to try to learn.  But I am very curious about what I've observed.   What little I know I have learned with the help and  input of several others including Dr. Croat, Julius Boos, LariAnn Garner and several others who are very knowledgeable.  These researchers and collectors have given me their observations almost daily during the past month.  I have been made aware of a few other Anthurium regale specimens in North America currently in flower.  If you possess one of those aroids I would certainly be interested in having you compare my observations to your own plant and forward your comments.  One field researcher who has worked with Anthurium regale in Peru, but prefers not to be named, made this comment to my question to Dr. Croat,
"Do remember dogs and bugs have far greater numbers of olfactory cells than we humans have. Consequently there is a good possibility that you are not able to smell what an insect, bee or some other beetle might smell. I have never noticed a smell with most of my anthuriums including regale."   So perhaps my observation has no validity at all.  Dr. Croat's comment about the species not being from Ecuador was in regard to another project involving Ecuadorian species for which a number of us have volunteered.  The measurements of the spathe and spadix Dr. Croat suggested have been made and recorded throughout the photo history of the growth of this spathe and spadix.

 Day 33:  No evidence of pollen production is yet visible.  This morning I received an excellent "lesson" in Anthurium reproduction biology from "Dr." Julius Boos, "Concerning the fact that you and others cannot detect any scent on A. regale does not surprise me, as many Anthuriums (and other aroids) do not produce an odor that is readily detectable to the human nose!  A few species are considered 'fragrant', and breeders are presently trying to 'work' these pleasant fragrances into Anthurium hybrids, and thus make them even more attractive to potential shoppers!  Lets bear in mind that the human nose is one of the least sensitive!   Think of the male moth that can detect a receptive female from miles away, but a human can smell nothing with his nose held inches away from a receptive female!"

Julius then went on to explain why my "theory" of the liquid not tasting "sweet"  was of no consequence,  "As to taste, the same 'syndrome' seems to apply-- what is 'unpleasant' to your taste may be lovely to others and/or insects, but maybe only to small beetles, tiny fruit-flies or ants!   I can not help recalling a refreshing and sweetened drink we brew locally in Trinidad from tree-bark and fragrant seeds, which we call 'mauby', it has what is to nearly every person (especially Americans!!) who as an adult tries it for the very first time, a revolting taste, certainly a distasteful bitter after-taste to the first 'sweet' taste, but to us Trinidadians who have been drinking it from youth, there is nothing better!

Again, "Dr." Julius makes his point understandable, clear and vivid!  He then went on to explain that some pollinators are drawn only to very limited scents and some to only limited colors.  Regarding my query to Dr. Croat as to the plant's "rarity" in nature, he commented, "I believe that much more observation in the wild will be needed before we can speculate on this.   This plant may not be, or may not have been at all rare in the wild in recent times past, and may, under natural conditions, produce a full infructesence.  Man`s destruction of its natural habitat might be responsible for its present scarcity (if in fact it is scarce in its habitat!) and also may have caused the reduction or lack of natural pollinators."

Then Ted Held forwarded this observation, "Here is a story related to me by a fellow keeper of Cryptocoryne, a family of marsh aroids. I mentioned to him that I could never detect any discernible scent in these flowers except for a sort of generic "musty" smell, which permeates marsh plants and their containers. He mentioned that lack of scent had been his experience too. But he also said that when he removed flowers to outdoors for photography (trying for natural lighting) that the flowers would attract insects from his backyard almost immediately. The moral is that what you can detect might be different from what an insect (or other pollinator) might be able to detect.  Maybe this is a corollary to the stench emitted by many aroids.  What is stench to us may seem like a T-bone steak to an insect."

So much for my theory!

Day 34:  No visual evidence of male anthesis.  Approximately one week ago Dr. Croat mailed a copy of his paper "Flowering Behavior of the Neotropical Genus Anthurium (Araceae)".  I have been attempting to absorb even a bit of his years of observing this group of aroids.  In his latest note Dr. Croat made these comments which I believe will be useful as the next phase of this anthurium species' reproduction behavior reveals itself:  "
If you are past female anthesis it should start to go through its male phase and stamens should start emerging, typically from the base and working upward.  Here is where you can really make a contribution because the pattern of emergence is often species specific.  Read my discussion of flowering behavior that I sent.  Make note of the first emergence and follow each day.  Usually one or two lateral stamens emerge, later the anterior one and still later the lower anther.  Make note of the pattern and the extent to which they are emerged.  If they are very emergent they will also retract after about 24 hours.  There are all kinds of variations and this species has never been studied to my knowledge.

This afternoon "Dr." Julius made these observations, "I had noticed the stigmas, the little 'nipples' at the center of each individual flower in the middle of the four scales of the perigones, (the  ''tip of the perigone'' is how you referred to it) are turning brown and drying up for a few days now.  But since I expected this, I have not mentioned it.  It started at or near the bottom of the spadix and signals the end of the female anthesis on each individual flower.  So we can expect once male anthesis begins, perhaps in a couple days, it will be at these flowers we may first observe pollen.   Look for the yellowish or cream or white powder of pollen near the bottom of the spadix, then put a good hand lens on that area, you should then be able to see the male parts (stamens) as described by Tom Croat.   This should take place for a length of time, starting at or near the bottom and working itself upwards.  When the uppermost flowers have completed producing their pollen both anthesis (male and female) will be over, and we must then wait and see if you get lucky... and if in this species may produce a few viable seed in a very few fruit.   If not, the whole infloresence will die and drop off shortly after male anthesis is completed."  If you look at the center perigone in the second row from the bottom on the extreme photo you can see the drying stigma as Julius described.  It is in this region we will be looking for the first appearance of stamens.

Day 35:  No visual evidence of stamens or pollen.  I received an email from an anthurium grower in Hawaii two days ago with an interesting photo attached.  This grower successfully grows many rare anthuriums and has a large number of Anthurium veitchii that regularly produce seeds.  The photo was of a fruit fly pollinating one of her Anthurium veitchii.  I often have fruit flies (likely a different species) in my atrium.  So I have now placed several wedges of fruit at the base of the Anthurium regale to attract insects.  They're all over the fruit!  But apparently "my" fruit flies don't care for the scent of the Anthurium regale!  Not a single one is landing on the spadix.  The photo on the right is an extreme magnification done in an attempt to view any hint of stamens.

Day 36:  Male anthesis may be beginning.  If you look closely you can see something emerging from a few stigmas on the lower left side of the spadix.  Those tiny "fuzzies" are known as stigmatic hairs.   Dr. Croat explained , "The stigmatic hairs are designed to entrap the pollen grains.  These trichomes may also induce germination of the pollen grains.Additional stigmas appear to be drying.  The first photo is more than double life size, the second approximately 8 times life size.
Day 37:  A few additional "fuzzy" stigmatic hairs can now be observed. 
Day 38:  Still just a few areas of stigmatic hairs are visible.  Julius feels he could see just a bit of pollen in the lower left corner on the Day 37 extreme photo.  I went out to check this morning but unfortunately yesterday was watering day so any trace would have been washed away.  Still no obvious evidence of a scent.  Julius and I have come to the conclusion this species is slow to develop.
Day 39:  Still only a few stigmatic hairs are visible.  No visible sign of pollen and still no trace of the scent Dr. Croat has prompted me to describe.  If you have read this entire discussion you are aware of the difficulty in causing this species to grow fertile seeds due to self pollination.  Many people who successfully grow Anthurium species have offered advice on how to make pollination of this spadix possible.  However, as explained previously, this species is not one that normally self pollinates.  A source of pollen from another plant is required and at this point no source is available.  One of the main goals of this exercise is to collect and freeze pollen for the next spathe and spadix that will eventually form.  However, some advice has been forwarded by a very successful grower that may make it possible to accomplish that goal once pollen begins to form.  This is the text of a recent email on the subject.  Once pollen forms on the lower portion of the spadix it is collected and applied to the upper portion with varying degrees of success.  The writer prefers not to be named.  By using this method it has been possible  to cause self pollination of aroid spadices:  "I have had mixed results with this method. Sometimes self-incompatibility trumps everything although with some aroids there is a simple way to circumvent that barrier. I use rain or distilled water, bring it to a boil, let it cool and add 1 or 2 drops of honey to a teaspoon of the cooled water and paint the female flowers with it and dust with pollen right away. Depending upon the humidity I sometimes put a plastic bag over the flowers for 1 or 2 days. A mold will occur if the humidity remains too high for too long."  And then came the same advice Dr. Croat has repeated many times: "I do advise sniffing the spadix for any scent at various times. The scent may last for only an hour or two and may occur either night or day. You should detect some odor when the first pollen shows up."   Several of us have attempted to smell any scent without success.  But we will keep "sniffing"!  One thing has become evident.  At almost 6 weeks into the process this species is slow to produce both anthesis and pollen.
Day 40:  The partially opened stigmaic hairs are visible up half the length of the spadix.  They appear as a slight "fuzz" at the end of each stigma.  Several clusters can be seen in the lower center of the extreme enlargement.  The entire spadix has also lightened in color.  Scroll back up to Day 35 and you can see the color changing from that point forward.  It is snowing lightly here today so the light in the atrium is extremely low.  That low light level reduces the contrast on the photo making detail less visible.  I will attempt to repeat these photos throughout the day to increase the possibility of sharper images but you can easily see something beginning to emerge.  No obvious evidence of pollen or a scent.
Day 41:  Today the sun is bright.  The stigmatic hairs are now quite evident.  Several knowledgeable observers do not feel the stamens have yet emerged.  LariAnn Garner wrote, "After careful study of the most recent photos of the A. regale spadix, I must say that in my humble opinion, stamens have not emerged yet.  In my experience, stamens are additional structures that appear surrounding each pistil, and they are a distinctive color that is different than the color of the spadix.  Most I have observed are white, creamy, or yellow."  She then continued, "The distinctive change in the tips of the pistils could be related to the closing down of receptivity of same in preparation for stamen emergence, as is the drying out."  So again we wait and watch.  Two additional items were observed.  The spadix continues to become lighter in color, and today, for the first time, there is a slight musty scent.

Day 42:  The scent is still very light.  No pollen or stamens are visible.  The spadix continues to brighten in color and is now nearly yellow.  In response to the changing color of the spadix LariAnn Garner had this observation, "I was thinking about the color changes you've observed in the spadix, and decided to share a few observations of my own.  My Anthurium. ochranthum has thrown enough inflorescences for me to have seen all the color changes that can happen with it.  The spadix starts out solid green when female anthesis is imminent.  As female anthesis progresses, the color lightens slightly and once male anthesis commences, the spadix has turned to a yellow-green color.  As male anthesis progresses, the spadix turns more yellow, then to a yellow-orange color.  The stamens and pollen are light orange on this species.  However, stamen and pollen color are not an indication of what color the spadix might turn to, as the birdsnest types have dark purple spadices at male anthesis, yet the stamens and pollen are a light creamy color.  If successful pollination has occurred, the spadix turns back to a deep green as male anthesis concludes and berries begin developing.  As berry development progresses, the color darkens and eventually turns to a purplish green.  If pollination did not take place, the spadix turns gradually to an orange-purple color, then to all purple as senescence sets in."
Day 43:  The stigmatic hair "fuzz" at the end of each stigma is very evident today.  Still no evidence of stamens.  The entire spadix appears to continue to change color.  Interestingly, the plant has already begun to add new growth.  A new leaf appears to be developing at the same time the spadix is maturing.  The new growth has already reached 11cm (4 5/16th inches) on January 30, 2007.  See the photo below.
Day 44: Today we are again experiencing a light snow storm and extremely cold temperatures.  The low light levels again make quality photography difficult.  The temp in the atrium remains stable at 55 degrees F or higher.  Stamens, as described in the technical information provided by both Julius Boos and Dr. Croat, do not appear to have yet appeared.  However, perhaps they are beginning to emerge since "something" appears to have emerged from a few stigmas approximately 1/3rd up the spadix on the left side of the extreme photo.  Julius made these comments today, "What I think I see happening is two-fold, the stigmas are increasing in length, growing 'taller', and in the area on the left of the last photo I can see were several have suffered some sort of mechanical injuries, and a couple have actually been broken off, one top of a stigma is actually stuck to another, and I can see the remaining short basal 'stub' of another, while another is sort of cracked, with the top portion still attached to the bottom, but sort of broken/leaning over.  I think the 'fuzzies' we see are physical changes to the very tip of each stigma.  This is happening (has happened) as a change after female anthesis when the liquid dried off the end of the tips as the height/length of each stigma continues to increase.  The male anthesis/pollen shedding does not seem to have begun as yet."
I am uncertain what has caused the damage to the stigmas but they can be seen on the ends of several.  On one it appears to also have a small water droplet hanging on the tip.  The larger water droplets on both sides of the spadix are humidity drops that have fallen from the ceiling due to the 95% humidity inside the atrium. 
To view photos after Day 44 go to Page 5 by clicking on the link below.


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