Within our collection we have many species of Philodendron. If you are seeking other photos, click this link:
This page is the photographic
documentation of the development of a spathe and spadix of
Philodendron sagittifolium during anthesis (reproduction).
It is important you read the link just below before
reading the information on this page. If you do not have a basic
of the pollination
of aroid species you will not be able to adequately comprehend all of the information
in this article. If you have already read this link, please
The leaves of Philodendron sagittifolium can grow quite large and the inflorescences stand erect. The plant is capable of producing one or more inflorescences per axil. I have previously described the "axil" as a plant structure but the correct explanation of the term "axil" comes from Dr. Tom Croat, "The “axil” is not really a plant structure but quite simply the axis of the stem and petiole. Inflorescences emerge from a bud in the axis of the petiole."
We have physically observed up to 5 inflorescences at the same time on our specimen. However, the color and shape of the spathe may be variable and may not match the photos on this page exactly. A spathe is not a flower, but instead is simply a modified leaf used for reproduction. The flowers, both male and female, develop on the spadix at the center of the inflorescence. Reproduction is explained by Julius Boos in the above link.
The peduncle, which is the plant structure that supports the spathe, normally measures 4 to 5cm long (1.5 to 2 inches). The spathe is somewhat flattened and green, but is often tinged with red on the inside. The spathe usually measures 8 to 22cm (3.4 to 8.6 inches) in length. The spathe below is on the larger end of that scale. But since the spathe can be somewhat variable the interior is sometimes not the color shown. We have observed the spathe to be narrow at the center but that does not always occur as can be seen in the photo on the main page of this website for this species. We have observed small spathes that are almost totally tubular.
Philodendron sagittifolium can produce an inflorescence almost any time of the year, but normally after the beginning of the dry season and continuing throughout most of the rainy season. We typically see the spathe and spadix in our artificial rain forest in May and June of each year. In nature, there is a slight shift based on geography when the "flowering" begins about one month earlier in Mexico and Guatemala (late winter) but less frequently in September and October. Inflorescence production continues longer in Panama and is seen in February through September and has rarely been observed in December. Once pollinated, the fruits take approximately two months to mature. However, in our atrium, we do not have any natural pollinators (beetles) present to service this species so we have never observed the development of fruit.
Pollination in nature is done by a species of Scarab beetle. The beetles remain inside the spathe only long enough to pollinate the female flowers, eat some of the pollen, find shelter from the cool rain forest night, and breed.French researcher Dr. Marc Gibernau from the University Paul Sabatier in Toulouse, France has studied aroid pollination since 1998. Marc added this explanation, "one reason for the beetles to leave the inflorescence which is a great place to stay is that the spathes close and force the beetles up along the spadix. Once above the male zone they will eat some of the pollen. If they don't go up they can finish by crashing the spathe against the spadix, I observed it once in French Guiana. So the plants "decide" when the pollinators arrive and depart." The Cyclocephala beetles in Marc's photo can be seen near the bottom of a Philodendron spadix as they eat the pollen.
In both early May and in early June of 2008 we had groups of spathes develop on each of two axils. The photos here of a single specimen developed on our Philodendron sagittifolium in June and then entered anthesis. This time I was determined to track that inflorescence photographically and as a result stayed up almost continually for some 36 hours plus. This is the photographic record of the opening and closing of that spathe over a 2 day period. Some of the information is simply my personal observations but other material (which is credited )was provided by aroid botanist Dr. Tom Croat of Missouri Botanical Garden who is America's top aroid botanist. Additional material was taken from his published journals. A great deal of the information and explanation was provided by aroid expert Julius Boos with input by Marc Gibernau and Leland Miyano.
A note of explanation:
The spathe of Philodendron sagittifolium was first noticed in the early morning hours and was not fully open. The event began well before we made the first observation. There is a second spathe directly behind this one, another to the left, and two above. All will eventually opened in progression and all are on the same axil a total of 5. The spathe measures 21cm (8.25 inches). This photo were taken in the late afternoon on day one of the event.
There is a slight smell of mint to the pheromone produced by the spadix. The pheromone is a fragrance used by insect pollinators as a "guide" to find the spathe in the darkness of the rain forest. If you are unfamiliar with the pollination in aroids READ THIS LINK before continuing. Otherwise, you will not understand the progress of these photographs. The red dots were not there this afternoon, but are clearly visible now. Dr. Croat explains below.
French aroid pollination researcher
Marc Gibernau provided these additional comments: "I
found it surprising the resin is produced a few hours after the
botanist Dr. Tom Croat explains the red dots which is a naturally
"The resin gets on the beetles and makes them sticky so that when
they leave they can carry away the pollen which otherwise won’t
stick to their bodies."
No significant change but an added note on pollen production which I had been asked to attempt to observe and photograph. Normally during the evening the plant in a wild setting would produce copious amounts of pollen which would "string" downward. The exact timing of that pollen production depends of several factors. Each evening I did my best to check the photographs for any sign of pollen but never was able to observe any. Julius Boos provides a possible reason, "Let`s keep in mind that some Philodendrons will not or do not produce pollen in cultivation The famous Philodendron spiritus sancti being one of those species. My opinion on a ''why'' is that conditions in the green house are just not right. At least not to the plants that need to enable it to produce the usually very obvious and copious amounts of pollen seen in other Philodendron which seem to ''like'' their growing conditions. Recently I saw many Philodendron xanadu blooming in beds at a large commercial property, blooms were at many stages, some fully open (the tops of the spathes, that is). Others produced pollen like crazy, and still some were closed with only the tip of the spadix visible and the spathe closed tightly around it. Ron Weeks reported that his plants (possibly in a greenhouse) bloomed, but never opened ''correctly'' or produced any pollen."
Although we do
everything possible in the Exotic Rainforest atrium to provide "rain
forest" conditions including high humidity, multiple overhead
watering twice daily, and as perfect slightly filtered light as is
possible, it appears the plant still knows it is not in its natural
The pheromone is not apparent early in the morning and no heat from thermogenesis can be detected. For an explanation of thermogenesis and the heat it produces, read the link provided above.
The spathe has rotated close to 20 degrees to the left. Although no female flowers have ever been present in any photograph, they are there! The explanation as to why we cannot see them is found later on this page. It is not strongly evident but the pheromone has begun to return as has the heat of thermogenesis The scent has changed somewhat and the mint smell is no longer apparent. All that is now noticed is a musky smell. Both my wife and oldest daughter could easily detect both the heat and the pheromone. To detect the heat all that was necessary was to hold a flattened palm in front of the spathe without touching any part of the inflorescence.
French aroid pollination researcher and expert
Marc Gibernau has stated the spathe and spadix lie at an angle of
approximately 45 degrees to the vertical for a purpose. The
angle is more effective for the heat of thermogenesis to be
dissipated along with the spadices' pheromones into the air of the
rain forest night. Notice what occurs in the next
The spathe has now rotated to a 45 degree angle on the axil in to increase the effects of thermogenesis. It also appears to be slightly closing. I have read in some material the spathe actually closes around the beetles and they do the work of pollination inside the closed tube. However, Julius offers a better explanation below. The pheromone is now only slight and no heat from thermogenesis can be felt on the hand. The scent is of a slight musk combined with a small amount of mint. Again, no female flowers can be observed but the explanation follows.
From Dr. Tom Croat,
"the receptivity of the female flowers is short once the spathe
is open. They are protogynous, of course, like most Araceae but
also promptly timed to be receptive only at anthesis on the first
night of flowering. This prevents self pollination."
And from Julius Boos:
blooming/anthesis cycle of this species lasts 2 days. The lower
portion (the tube) of the spathe never opens in this species,
probably in the entire genus. I do not believe that this
spathe could trap the Scarab beetle pollinators even if it wanted to
as they are strong animals. I once collected about a dozen of them
from a bloom in the jungle of E. Ecuador, and was unable to ''hold
on'' to them for long as they would burrow (painfully, I may add!)
between my fingers and out of my tightly closed fist.
This is a totally different spadix photographed more than one week later. "Pollen" appears to be seen beginning to develop near the apex (top). Please read our note below regarding the consistency of this "pollen".
The spathe has been sliced away in the photo (right) to allow exposure of the interior. As you are about to see and read the spathe will soon close around the spadix blocking all view of the interior. The photo to the right was taken at approximately 6:30PM on the second day of the event. Dr. Croat commented, "When the pollen emerges usually there is no doubt. It comes out like toothpaste from a tube that has been stepped on but in slender threads." It appears the spathe is just beginning to develop "pollen" but we were never certain it was pollen we were seeing. The "pollen" appears to be dampened. In a personal meeting in his office in late June Dr. Croat indicated the "pollen" in my photographs appeared to be old but the photos were taken just after the spathe opened and as the pollen at least "appeared" to be produced. I have no explanation other than humidity and moisture for the effect seen in the photograph but am not totally convinced I was ever photographing pollen.
If this is "pollen", the consistency on the spadix at
have been altered as a result of the perpetual high humidity and twice daily
overhead misting in our atrium. Our atrium is often watered twice
each day to simulate a natural rain forest. Normal Philodendron
pollen (photo left) is much "fluffier" and not as compacted as is seen in this and
photographs below. We are attempting to verify if the pollen for this
species should normally be this compressed and "thick". Julius
don`t see the typical pollen 'threads' which are rope like on other Philodendron
sps. Aside from the watering, which may have washed the pollen threads
away or at least diluted or thinned them, I do see what looks like a paste-like
substance where pollen should be seen."
The photograph of the "pollel" is of a second spadix with the spathe cut away, not the one in the original photographs seen on this page. The spathe lamina began to wrap so tightly around the spadix the outer layers had to be cut away to reveal the interior. The event could not have been observed or photographed without the removal of the shielding spathe lamina which was blocking the event inside the spathe from view.
So now we know "where" the male flowers were all along, but where were the female flowers?
So where are the female flowers?
Julius Boos' excellent explanation of what I could not originally see.
Read this carefully. It explains a great deal of what I was missing!
I've added the photo of the spathe cut away so you can examine it as you
read. This second photo has been purposely left enlarged.
The first shows the zone of female flowers which is hidden beneath a
portion of the lower spathe.
Above this is the
resin covered and stained male section of flowers extending upwards to
the tip of the spadix. In this case the spadix is said to be fertile to
the tip, but in some Philodendrons and in some other bisexual aroids
there is a sterile area of male flowers near the tip (or apex) also thought to be
involved in scent production. At male anthesis the fertile portion would
be seen to be covered in pollen extruded by the male flowers, this
pollen under natural conditions in the jungle would adhere to the
emerging beetles glued to their shiny surfaces by the resin seen as a
reddish stain on this portion of the spadix.
Marc Gibernau added,"The sterile zone just above the female zone is constituted of sterile flowers rich in lipids which are normally eaten by the beetles. I don't think that they produce any scent (but I'm not 100% sure). I would more suspect the male flowers produced the odor. If you have more inflos coming up you can verify this point by wrapping plastic bags around the 2 zones and smell them after a while, but don't wait too long because during the heating period they will fill with water because of the exaggerated evaporation."
My sincere thanks to Dr. Croat, Julius Boos, Marc Gibernau, and Leland Miyano. This message came from Dr. Croat after briefly reviewing this page: "I read your piece on the flowering behavior of Philodendron sagittifolium and can find no fault with it."
If you failed to read the link below much
of the information found on this page will be of little value!
Want to learn more