#2- Mexican Sycamore -Platanus mexicana or Platanus rzedowskii
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Strengths and Weaknesses Listed
All of our plant information sheets will eventually include a section on weaknesses instead of just strengths. All trees have weaknesses and strengths. In order to thoroughly evaluate a tree, you should consider both. Let me begin by offering some strengths of Mexican Sycamore and then I will describe some weaknesses. You will be happy to discover that this trees strengths overcome its weaknesses! In fact, from our viewpoint, Mexican Sycamore is near the top of the list coming in at #2. Perhaps it will become your number #1 choice.
Strength: Beautiful Large Leaves: This tree has beautiful large leaves. It has the largest leaves of any quality shade tree on our market today. Young trees and young shoots may have very large leaves. It is not unusual to find the largest leaves of Mexican Sycamore measuring 15 ½ inches wide, from point to point, across the width of the leaf, and 11 inches long from top to bottom! The leaves look like giant maple tree leaves. One should not expect to see a mature tree covered in these large of leaves. Leaves tend to mature to a “less large” size, with time, in full sun or where conditions are consistently on the dry side. On a mature Mexican Sycamore it might be common to find leaves 9” inches wide and 7” inches long, still very large. Of the quality shade trees in our area, Mexican Sycamore offers the largest leaves, even larger than American Sycamore.
Strength: Visual and Actual Cooling Effect
These large leaves provide a nice cooling effect. South-Central Texas gets hot and some of our landscape features seem to make it look even hotter, like a yard filled with rock and cactus in the blazing sun! But a Mexican Sycamore makes it look cooler and actually provides cooling shade from the hot summer sun.
Strength: Attractive Leaf Color on Both the Top and Undersides
Underside Leaf Color
Perhaps the most distinctive identifying characteristic of Mexican Sycamore is its leaf color, especially the underside of the leaves. The undersides of the leaves have a very distinctive whitish color that is especially noticeable when the wind blows. Even when the wind does not blow the large leaves hang downward making the underside more visible. In addition, some leaves are positioned on the stem in a reversed fashion so that the bottom side leaf is presented to the viewer as much as the topside.
This underside color is caused by fine, short, woolly, downy, cotton like hairs that cover the backside of the leaf surface. The whitish/silver color is similar to that of Silver Maple (Acer saccharinum) but Mexican Sycamore is far superior to the Silver Maple for our area. You could think of the Mexican Sycamore as the “Silver Sycamore” and you would be partially right.
New Leaf Color
When new leaves emerge they are often whitish to a very light green color on both the top and underside, and so the tree has areas that do appear silver with only a shade of light green. As leaves mature, the topside develops more of a light green to medium green hue and finally an olive green. This provides an attractive progression and contrast of color throughout the tree.
Top-side Leaf Color
Consider also the beauty of the mature topside leaf. Some leaf topsides eventually shows off a medium, olive green color. These leaf color differences are especially noticeable when the trees are well watered and not under any kind of environmental stress, such as drought stress, or fertilizer deficiency in nursery pots. Adverse conditions may cause the Mexican Sycamore to take on a yellow green cast or a lighter green hue on the topside. When trees are exposed to intense sunlight over a long summer they may also take on a yellowish green cast. These color characteristics change and progress throughout the growing season dependent upon the environment it finds itself in.
The darker green topside leaf color of Mexican Sycamore is partially the result of the prominent white underside. This white downy growth actually makes the leaf thicker and blocks some sunlight from penetrating through the leaf. This makes the leaf less translucent to sunlight and therefore it appears a darker green since less light passes through. If you were to take a leaf of any tree, hold it up to the sun, and then put your palm behind it, or a blank sheet of white paper, you would cause the sun to be blocked and the leaf would appear a shade darker. The whitish downy underside growth does the same for the Mexican Sycamore leaf.
Strength: Leaf Color Enhanced Through Alternatively Positioned Leaves
The weight of the larger leaves tends to cause individual leaves and lower branches to drupe downward. The leaves are alternatively positioned on the drooping stem with the bottom side facing, at times outward. So when you look at the branch it alternatively shows its topside on one leaf and its bottom side on the alternate leaf, quite a contrast. The leaf tops of some of these drooping leaves are also pointed downward rather than the more common horizontal or upward orientation. This is unique and reveals the bottom side leaf color even more. We will discuss how this branching and drooping reveals the bottom side leaf color more extensively below.
Strength: Brightens Up A Dark Native Landscape
Mexican Sycamore's medium green leaf topside color and whitish underside brightens up a dark native landscape filled with the darker green leaves of Live Oaks, Cedars (Ashe junipers) and Cedar Elms. When looking at a native tree canopy, you would certainly appreciate the nice visual contrast the Mexican Sycamore gives. In addition to the leaves, the tanish to white mottled bark peels away as the tree grows revealing even whiter bark. The trunk appearance gives the same effect as that of a Birch tree in New England or an Aspen in Colorado or a Crepe Myrtle throughout South-Central Texas. Mexican Sycamore bark is noticeably white. The lighter bark of Mexican Sycamore contrasts nicely with the dark bark of Live Oaks, Monterrey Oaks and Cedar Elms and so brightens up our dark-trunked native landscapes as well.
Strength: Great Large Shade Tree: These trees grow moderately large. The grand champion Mexican Sycamore tree growing on the campus of Trinity University in San Antonio measures about 70' feet tall. In the shallow soils of the Hill Country you will still get a tree exceeding fifty feet with a wide spread as well.
Strength: Fast Growing: Of the quality shade trees Mexican Sycamore is the fastest grower. A growth rate of five feet per year is not unusual. Compared to other quality shade trees, its growth rate is about one third to twice as fast, during the first five years, as other quality trees, such as Monterrey Oaks and Texas Red Oaks which are moderately fast growers as well. It may be the fastest way to beautify a new yard, commercial property, or neighborhood.
Strength: Very Popular: This tree has become very popular throughout the San Antonio area in recent years rivaling even Monterrey Oaks in popularity. Mexican Sycamores are being planted, especially in commercial installations as landscape architects “in the know” propose them in their designs. Mexican Sycamore has not yet caught on as extensively in the residential market, but in time this should change as homeowners become more aware of this trees beauty and value.
Strength: Pleasant Smell
Have you ever walked through a grove of Sycamore trees and noticed the sweet pleasant smell. It is a smell that is hard to describe because it is unique. It is a smell reminiscent of pleasant shady places along rivers and creeks. And just like its American cousin, Mexican Sycamore is found in the same types of environments in its own original native home.
Strength: Drought Tolerant
The Mexican Sycamore is a tough survivor and surprisingly drought tolerant. Even though in its native Mexico it grows naturally along rivers and streams, it is still well-adapted to upland sights. During severe summer droughts when it hardly rains for two months, the Mexican Sycamores will drop some leaves and not look as awesome. Newer plantings could even die without supplemental irrigation. If so, normally these new plantings will re-grow from the base. Never a total loss, considering how fast a Mexican Sycamore grows. However, established trees should survive and return to being attractive when rains returns.
Strength: Disease Resistant
Mexican Sycamore is marketed as being very resistant to a couple of problems that our native American Sycamore has been known to have, especially in other parts of the country and our state. Mexican Sycamore, though similar, should not be confused with American Sycamore when reading about Sycamore tree problems .The lesser problem of American Sycamore is called Anthracnose and can occur in wet cool springs. This fungus can cause some leaves to turn brown and fall off but new leaves will quickly replace the old and usually no lasting damage is done. A more damaging disease for American Sycamore is Bacterial Leaf Scorch which can happen in the summer and cause some damage to limbs, die back of the crown and weakening of the tree over a number of years. This has been a problem elsewhere, but not in our area. American Sycamore trees continue to thrive all throughout Texas and most of the Country. Nevertheless, Mexican Sycamore is more resistant to these problems than American Sycamore, even though these problems are not a big issue here with American Sycamore either.
Weaknesses of Mexican Sycamore
All trees have strengths and weaknesses. You should consider a trees weaknesses, as well, when making an informed decision. You will be happy to find that this trees strengths overcome its weaknesses.
Weakness: Not As Long Lived As Oak Tree Choices
Mexican Sycamore is not as long-lived as other good choices such as Monterrey Oak or Texas Red Oak. And of course, no tree, good for our area, comes even close to living as long as a Live Oak. This lack of longevity, perhaps living a hundred years, keeps the Mexican Sycamore at #2. If you want to leave behind a legacy for future generations and neighborhoods, the Oak trees are a better choice. If you want to enjoy a large tree while you are still alive, even though your grandchildren may not, consider the Mexican Sycamore.
Weakness: Drought Tolerance Exaggerated:
I have seen many Mexican Sycamore trees doing quite well under drought conditions. But as drought becomes worse, I have seen trees lose leaves until rains return, but not die. There is “drought tolerance:” the ability of a tree to stay alive during drought and then there is “drought looks”: the ability of a tree to still look good during drought. Other large shade trees like the Live Oak and Texas Red Oak will look less effected by drought than Mexican Sycamore.
More Drought Tolerant Than American Sycamore?
Keep in mind that the Sycamore trees native to South-Central Texas are called American Sycamores (Platanus occidentalis) not Mexican Sycamores. However, the two are very close cousins and so look alike in many ways. But as was the case with the “over- marketing” of the drought tolerance of certain turf grasses, so goes the Mexican Sycamore's marketing story as well. Many professionals are excited about the drought tolerance of this tree. The fact is that American Sycamore and Mexican Sycamore are about equally as drought tolerant and surprisingly quite drought tolerant at that. Drought tolerance is really not a weakness of American Sycamore when compared with Mexican Sycamore. Along these lines the drought superiority of Mexican Sycamore over our Texas-native American Sycamore has been overstated. Even though both of these trees grow naturally along waterways, yet they both do well in residential and commercial settings in terms of drought tolerance.
Weakness: Not as Good of Fall Foliage as American Sycamore
There is one comparison with American Sycamore that I think the Mexican Sycamore loses on and that is traditional fall foliage. I say “traditional” because Mexican Sycamore does have an interesting fall appearance but the look comes late and the color is non traditional- yellowing foliage on what leaves remain, coupled with the white leaf undersides. Interesting and even attractive, almost like Christmas ornaments on a “Charley Brown” tree! but not the normal fall foliage one would expect. The American Sycamore, on the other hand, is one of our best fall foliage trees in the Hill Country. The immediate San Antonio area does not usually enjoy as vivid of fall color, on any type of tree, due to the lack of cool nights and dry sunny days and the presence of fall rains which encourage new green growth rather than fall foliage.
Weakness: Not Technically Native to Texas
Many of us agree that we need to plant Texas native trees. Consider that the Mexican Sycamore is not technically native to Texas. Besides, we have a great Sycamore tree that is native to Texas that we should be planting more. Yet, we can plant both and have the best of both worlds!
The Sycamore genus (type of tree) is native to Texas, Mexico and many other places. The Mexican and American Sycamores are very close cousins. In addition, the idea that we should only plant natives has been modified by most of us. We now realize that, not only should we plant natives, but we should plant well-adapted trees too. And so we have many examples of plants and trees from all over the world that do well here and the Mexican Sycamore is one of those, though not so far from home.
Comparing/Contrasting Mexican Sycamore-Platanus mexicana and Platanus rzedowskii To Our Texas-Native American Sycamore -Platanus occidentalis
It is not as if we in the San Antonio area have never seen a Sycamore tree before. One need only take a short drive out in the hills to see our native creeks dotted with groves of Sycamore trees, always a beautiful sight. These trees, that grow native along our creeks are technically called “American” Sycamores (Platanus occidentalis). They also grow throughout the United States.
Our native Sycamore has been underused because of the fear of Sycamore diseases that other parts of the state and country have experienced, and lately, because of overwhelming enthusiasm for the Mexican Sycamore. Yet, these diseases have not been a big problem in the San Antonio area. One needs only to take a drive out into the Hill Country and notice all of the American Sycamores looking beautiful and healthy along our streams and rivers. You can also see many fine examples of American Sycamore trees growing throughout the San Antonio and South-Cental Texas area neighborhoods and throughout most of the entire country. The same can be said of another great tree that has been underused in our area because of the fear of disease elsewhere: the American Elm and the accompanying Dutch Elm Disease, which has not been a problem down here. Not all plant diseases thrive “down here!”
Similarities and Differences Between Mexican and American Sycamore
Both the Mexican Sycamore and the American Sycamore are beautiful and very similar in appearance and also very close relatives. It is not as if the Mexican Sycamore looks drastically different from its native Texas cousin. Both have large maple-like leaves. Both have beautiful whitish to tan bark that peels off as the tree grows.
Differences Between Mexican and American Sycamore
Different Underside Leaf Color
The main difference between the native American Sycamore and the Mexican is the more distinctive white underside of the Mexican Sycamore leaf. This has been its most identifying and desirable trait and is what many people think of when they speak of Mexican Sycamores. However, it is not as if American Sycamore does not have the white downy leaf underside as well. It is just not as pronounced on the entire tree as with Mexican Sycamore. I have seen many American Sycamores with white leaf undersides, especially on new emerging leaves. But the Mexican Sycamore underside is more prevalent and distinctive on the tree. This is especially true of the more popular varieties of Mexican Sycamore known as 'Alamo' and 'Trinity.'
Different Topside Leaf Color
Leaf coloring helps when differentiating Mexican Sycamore from our native American Sycamore. When comparing the two you may notice that the topside of a Mexican Sycamore leaf appears a shade darker than the American Sycamore leaf. The topside color is medium green, perhaps an olive green with a light shade of white mixed in. This is not remarkable in and of itself except that the very white leaf undersides create a unique contrast which really brings out the topside green color in a unique way. The American Sycamore appears a shade lighter green with a definite golden hue or yellow green color. From a distance, this overall color difference is one of the easiest identifying characteristics.
Whitish Leaf Undersides Effect Topside Leaf Color
The darker green topside leaf color of Mexican Sycamore is partially the result of the prominent white underside. This white downy growth actually makes the leaf thicker than American Sycamore and blocks some sunlight from penetrating through the leaf. This makes the leaf less translucent to sunlight and therefore it appears a darker green since less light passes through. If you were to take a leaf of any tree, hold it up to the sun, and then put your palm behind it, or a blank sheet of white paper, you would cause the sun to be blocked and the leaf would appear a shade darker. The whitish downy growth does the same for the Mexican Sycamore leaf.
Leaf Translucency Effects Leaf Color
On the other hand, the American Sycamore lacks the thickness of the white downy underside and so is slightly thinner and more translucent to golden sunlight. As sunlight more easily passes through the thinner American Sycamore leaf , the sun's golden rays give a golden hue to the American Sycamore. Each tree color is attractive and healthy in its own right, but different.
Growing Environment Effects Leaf Color
These leaf color differences are especially noticeable when the trees are well watered and not under any kind of environmental stress, such as drought stress, or fertilizer deficiency in nursery pots. Adverse conditions will cause the Mexican Sycamore, also, to take on a yellow green cast and the American Sycamore may appear more golden yellow or even brown. With or without irrigation and fertilizer, this yellow green color will immerge naturally, in both trees, as fall conditions begin and continue.
Reflective and Translucent Influences on Leaf Color
One might think that this gives the Mexican Sycamore more of a duller green color. To the contrary, the white leaf underside bleeds through to both the bottomside and topside leaf surfaces, especially on the younger leaves. This lights up the topside green, at times making it also a lighter green. The direction of incoming sunlight, or lack thereof, plays upon the color at any given time of day. In addition, the whitish underside reflects sunlight and so the Mexican Sycamore leaf seems brighter with more contrasting color from topside to bottom side. Yet, the Mexican Sycamore leaf is less translucent but more reflective. The American Sycamore leaf is more translucent and less reflective.
Differences and Similarities in Bark Color
Both the Mexican and American Sycamore have very similar bark color. Early in the season it is more of a tannish or light gray color on both trees. As the season progresses the bark peels away revealing a whiter inner bark that is very distinctive. Perhaps the darker green leaf color of Mexican Sycamore accentuates its white bark making it appear even whiter than American Sycamore bark.
Differences in Leaf Size
Both trees have large healthy leaves that are shaped very similar. All Sycamore trees are known for their large leaf size. A Sycamore trees leaves are larger than the various types of Maple trees throughout the country. A good description of a Sycamore leaf is that “it looks like a giant maple tree leaf.”
Young trees and young shoots may show very large leaves on both the Mexican and American Sycamore. It is not unusual to find the largest leaves of Mexican Sycamore measuring 15 ½ inches wide, from point to point, across the width of the leaf, and 11 inches long from top to bottom! Not to be outdone, the same can be said of some American Sycamore leaves: 13 inches wide from point to point, across the width, and 11 ½ inches long from the top to the bottom of the leaf. Climate and growing conditions and age effect the size of the leaves on both trees.
One should not expect to see a mature tree covered in this large of leaves. Leaves typically grow larger in shade and under well watered conditions and smaller in full sun or where conditions are consistently on the dry side. On a mature Mexican Sycamore it might be common to find leaves 9” inches wide and 7” inches long, still very large. Of the quality shade trees in our area, Mexican Sycamore offers the largest leaves, even larger than American Sycamore.
Differences and Similarities in Leaf Shape
Observations that claim that the two trees can easily be told apart by differences in leaf shape do not always hold up under closer scrutiny since any one single tree has leaves of different shapes. If you simply choose one leaf (halotype) as an exact replica for all other leaves on that same tree, you will find that not all of that particular tree's leaves fit its own model leaf. It is true that you could deliberately choose a leaf off of a Mexican Sycamore and then deliberately choose a leaf off of an American Sycamore to show that the two leaves have obvious differences in shape. On the other hand, you could also deliberately choose a leaf from a Mexican Sycamore and then find a nearly exact shaped leaf that matches an American Sycamore! So American Sycamore trees have some leaves that look more Mexican and Mexican Sycamores have some leaves that look more American.
Noticeable Differences in Leaf Shape
However, in general, there are some distinctions in leaf shape that are widespread and noticeable:
Smoother-Sided Leaf Lobes
The Mexican Sycamore has three distinct leaf lobes. The top lobe is a triangular or star-shaped projection pointed at the end and is in the 12 o'clock position. This pointed lobe may have a few lesser points on the side of the triangular projection but these points are few and not nearly as pronounced as the top point. One distinction of the Mexican Sycamore leaf, in contrast with the American leaf, is how relatively unpointed or untoothed the sides of this top lobe are. The American Sycamore's top lobe, on the other hand is less triangular and more rounded with many side points and also mini-lobes and indentions on the side of the top main lobe. It is less star-shaped as the leaf is more palm-like. The triangular lobe projections are more muted and there is less indentation between lobes. American Sycamore's top lobe is not as star-shaped although it is pointed and in the 12 o'clock position like Mexican Sycamore.
Then, there are the upper two side lobes, opposite each other. These extend out wide and horizontally on the Mexican Sycamore. As with the top lobe, these side lobes also have smoother edges with less toothing and mini-lobes than the American Sycamore. These two side lobes are pointed prominently on the top and bottom corner of the lobe. These more square sided middle lobes will have lesser points along the length of the square between the more prominent points in the corners.
So there is some degree of toothing and mini lobes on the three main leaf lobe edges on both the Mexican and American leaf. But the Mexican Sycamore has less toothing and mini lobes, with some leaves having almost completely smooth leaf edges like a star. Mexican Sycamore's top three lobes look more star-like than American. The top lobe and two upper side lobes can come to a single point on the star-shaped, smooth sided triangular projections. The American, on the other hand has more toothing on the lobe edges and more mini lobes on the outside edges of the main lobes. Its lobes also tend to be more rounded or palm like.
Using a traditional clock to illustrate, the top lobe of both species is in the 12 o'clock position. The middle lobes show some difference. The American's upper two side lobes are slanted upward in the 10 to 11 o'clock position and the 1 to 2 o'clock positon. The Mexican's upper two side lobes are sometimes more horizontal closer to the 9 to 10 o'clock and 2 to 3 o'clock positions respectively.
The bottom two lobes are not always distinct on either species, but when they are more defined, they tend to follow the same pattern of less toothing and mini-lobes on the Mexican and more on the American. When the two bottom lobes are less defined, the two look very similar. As will be also mentioned below one can find Mexican Sycamore leaves that look very much like American in their lobing patterns. But on the whole, less toothing and mini lobes are more prevelant on the Mexican Sycamore leaf. The leaf holotype (example) chosen by Nixon and Poole to represent the general characterisitcs of Platanus rzedowskii llustrates this distinguishing mark as well. See our discussion of Nixon and Poole, respected experts on the various kinds of Sycamore trees growing in Mexico, and the possibility that Platanus rzedowskii and not Platanus mexicana is the true originator of our San Antonio area Mexican Sycamores.
Growers of Mexican Sycamore
Various growers have attempted to grow Mexican Sycamore. The results seems to show that there are legitimate Mexican Sycamores that do not show as distinctive of features as others. Some of these trees were produced by growers who gathered seeds from Mexican Sycamore trees that possessed the qualities they wanted to reproduce, such as the distinctive white underside. Yet, some of these seedling trees did not inherit all those qualities to the degree that the parent tree possessed.
Hybridization of Mexican Seeds With American Pollen?
Some have proposed that what has happened is a “hybridization” with American Sycamore. The idea is that pollen from American Sycamore was present in the area where the Mexican Sycamore tree was growing when seed balls were taken from it for propagation. Even though the original growing parent Mexican Sycamore was purely distinctive in terms of the pronounced whitish underside, its seed balls became pollinated or “contaminated” with American pollen, thus the loss of some of the pronounced distinctive characteristics. Some would claim that these trees are inferior and could be referred to as “Tex-Mex” Sycamores. This theory has not been proven, and even if it were true, it does not prove that one tree is better than the other since hybridization tends to make a tree more adaptable to its new environment.
Legitimate Quality in Variety
In my first propagation efforts with Mexican Sycamore I had much success in getting seeds to germinate and grow into beautiful trees, but I did not have as much success producing seedlings with the consistently distinctive white undersides that I desired. On the other hand, I found that some of my seedlings did possess those qualities. I also found that most all of the trees I grew from seed did possess the “top-side” characteristics I wanted that I have described above. They did possess very large leaves with the medium mexican- green color. Some also had the distinctive star like lobes but others had more of an American Sycamore leaf shape. I planted one of these trees in my daughters yard 5 years ago and now it is about 30 feet tall and beautiful! It is not inferior at all. I have also recently noticed that more of the leaves are beginning to actually develop the distinctive white underside that I originally wanted. The tree looks very Mexican in every way but not all of its leaves are white underneath. The bark on the tree is distinctively white as well. It is the most beautiful tree on her street in her new neighborhood. I would highly recommend it and other Mexican Sycamores that may not be as distinctive from various growers.
Large Producers of Mexican Sycamore
Perhaps this problem of inconsistency is the reason why some large growers have produced and developed more specialized varieties of Mexican Sycamore through cuttings and careful selection of seedlings from which to propagate. By selecting the trees that most possess the qualities they desire, they grow the trees from cuttings to ensure more uniform results that display these characteristics from the beginning rather than over time. Two of the most well known varieties at present are 'Alamo' and 'Trinity'.
Trees Available At Wilson's
At Wilson's we carry the above varieties and our own variety that we have grown from seed. Occasionally we also purchase from different growers who have their own variety, whether it be named or not. We want our customers to see for themselves what looks best to them. Distinctive white undersides may not be as desirable a trait for some as for others. We have found that customers seem to like all the different shades of green and white Sycamores that we have. We also carry the truly native American Sycamore grown from Hill Country seeds and seedlings.
Understanding the Origins of Mexican Sycamore Better: Platanus mexicana or Platanus rzedowskii?
Until now, I have used “Mexican Sycamore” and “Platanus mexicana” interchangeably. But for those of you who are interested in understanding the true botanical name and origin of the trees called Mexican Sycamore that are being planted around here, the following more technical discussion is for you. I hope it sheds some light on the subject yet it may also confuse the issue even more. I, myself, am not totally convinced of the Platanus rzedowskii name designation, but I am intrigued, and it seems like a reasonable explanation. Hopefully with time, we will solve any mysteries that remain about the origins and proper naming of Mexican Sycamore. The following is a discussion of why some feel that the Mexican Sycamore being planted around the San Antonio area should be called Platanus rzedowskii rather than Platanus mexicana:
Obviously, Mexican Sycamore trees are native to Mexico and yet more recent research has shown that there are noticeable differences in the various kinds of Sycamore trees growing down in Mexico. Mexico is a very large and diverse country, botanically speaking. Early naming work by tree specialists was not exhaustive and thorough and so the name Platanus mexicana (which is simply translated as “Sycamore, mexican”) was used “up” to describe what is now considered to be only one species of Mexican Sycamore. Unfortunately, for us, this firstly named species of Platanus mexicana does not match the tree that is being planted around here.
So new discoveries of different species of Sycamore trees growing in Mexico have been made. These new researchers did not want to discount the naming that had already been done but needed a way to distinguish these new types of Sycamore trees growing in Mexico. They needed new botanical names to do this. This brings us to the discussion of whether Platanus mexicana is really an accurate name for our Mexican Sycamores. Could it be that a newly named species called Platanus rzedowskii is the real Sycamore from Mexico that is being planted around here?
This research has not been well known by the general public nor to many growers. Many growers have simply not cared much about the issue and have kept using Platanus mexicana to describe this new influx of white under-sided Sycamore trees, from Mexico, being planted all around. But, as will be shown, using the botanical name Platanus mexicana (Mexican Sycamore) tends to gloss over the new discovered species. In fact Platanus mexicana only represents one species of Sycamores growing in Mexico. One might get the impression that you need only simply cross the border and then you will find a Mexican Sycamore that looks like the ones that are being planted around here. An easy solution but one that may not be accurate.
Nixon and Poole Research
The most important work in pointing out these differences was done by Kevin Nixon and Jackie Poole.
Research by Nixon and Poole offer a more detailed understanding of Sycamore trees that grow in various areas of Mexico. In their publication, “Revision of the Mexican and Guatemalan Species of Platanus (Platanaceae)” they have identified variations in Sycamore trees and have announced “Platanus” named species and varieties to represent these differences not acknowledged before in such detail. This research was made public in 2003 but has not become common knowledge. Though it was not the primary purpose of their research, their research is helpful in trying to pinpoint exactly what type of Mexican Sycamore is being planted in the San Antonio and South-Central Texas area.
Using Platanus mexicana Confuses Proper Identification
Nixon and Poole believe that using the botanical name, Platanus mexicana, to describe all of the Sycamore trees growing in Mexico confuses the issue. What confuses the issue further is that Nixon and Poole believe that the name Platanus mexicana should indeed still be used to describe one original species of Mexican Sycamore. They have subdivided this remaining legitimate Platanus mexicana species into two varieties named Platanus mexicana, variety “Mexicana” and Platanus mexicana, variety “Interior.” But neither “Mexicana” or “Interior”match the look of the Mexican Sycamores being planted in our area. So the name Platanus mexicana has been “used up” and the idea is that it should not be used again to describe the other species of Sycamores growing in Mexico.
This research of Nixon and Poole, prominent experts in this field, needs to be researched further in order to figure out exactly what kind of Mexican Sycamore species is being planted here in South-Central Texas and what have they specifically named it.
Could Platanus rzedowskii Be The True Mexican Sycamore Being Planted Here?
One newly differentiated species Nixon and Poole have named is Platanus rzedowskii in honor of the Mexican botanist Jerzy Rzedowski for his work with Mexican woody plants and his collections of Sycamore specimens throughout Mexico. Of this species they say “Platanus rzedowskii is one of the most distinctive and beautiful of the species of Platanus.” They go on to describe some of its distinct features. Of special interest is their description of this species “densely white tomentose (short downy or wooly hairs) leaves” which separate its appearance from other Sycamores. This focuses interest on “rzedowskii” as the species of Mexican Sycamore that most closely resembles the trees that are being planted in our area with their “whitish downy hairs” on the undersides of the leaves as well.
Leaf Examples (Holotypes) of Rzedowskii Not Entirely Convincing
The totality of the evidence, however, is not entirely convincing when leaf examples of “rzedowskii” called “holotypes,” which Nixon and Poole provide, are examined. One would expect that the holotype leaves would closely resemble the leaf shape of Mexican Sycamore tree leaves that we can examine from trees growing in our area. The shape of some of the leaves of the Rzedowskii example do match the Mexican Sycamore variety called 'Alamo', for example. Yet other leaves of 'Alamo' look more like Nixon and Poole's holotype examples of Platanus occidentalis, variety occidentalis than they do of Platanus rzedowskii! See also our other discussion of differences in leaf shape between Mexican and American Sycamore for more on this.
Rzedowskii of Northeastern and North-central Mexico
“Rzedowskii” grows in the Northeastern and North-central areas of Mexico, especially in the Mexican states of Nuevo Leon and Tamaulipas. Nixon and Poole's “rzedowskii” has been claimed by some to be the special tree with the “whitish” leaf undersides that we think of when we say “Mexican Sycamore.” Perhaps these “rzedowskii” type trees were the ones from which propagation first began.
It seems that more verification, halotype samples, and especially feet on the ground are needed to
verify growing sights where these have been documented to grow. This would provide a great service to all of us who want to understand Mexican Sycamore better.
These new trees may have indeed begun with certain selections of rzedowskii cuttings and seeds but through selective propagation new enhanced results are being achieved resulting in some of the very distinct trees we are seeing being planted around here. With time, new named varieties will be produced that will become available. Already many have attempted to grow these trees from seed. Not
as many through more advanced propagative techniques.
Platanus mexicana Still Prevalent Right or Wrong
Trees with these characteristics certainly grow in Mexico, regardless of what they are named. But regardless of the interesting research of Nixon and Poole, the more common botanical name for our planted Mexican Sycamores, in this area, continues to persist as Platanus mexicana, right or wrong. Using Platanus mexicana may be an easy solution but it does not help in pinpointing exactly where our planted Mexican Sycamore's originated from and still grow.
A Great Tree, No Matter What You Call It!
The various Sycamore trees that grow in Mexico, whether “rzedowskii” or not, have been successfully propagated, for sure, and are available for sale! We may not understand Mexican Sycamore's origins, propagation history and proper name as well as we might like, but we can still appreciate the beauty and usefulness of this wonderful tree. I hope you will feel the same
Mexican Sycamores For Sale At Wilson's
Each year we usually have a good supply of Mexican Sycamores. Typically these are sold as 5 gallon, 15 gallon, 30 gallon and 45 gallon. Larger trees are available as well.
A Blessing For You
We hope that this plant information helps you as you search for that perfect tree. Whichever tree you choose, may it bring you many years of beauty and peace.
May you and your tree be “like a tree planted by streams of water which yields its fruit in season and whose leaf does not wither.” (Psalm 1:3)
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