Chamaedorea geonomiformis

[XYZ]

Chamaedorea geonomiformis is a fairly common, very handsome dwarf palm native to much of the Caribbean versant of southern México and Central America. There are also disjunct populations on the Osa Peninsula (Pacific versant) of Costa Rica and, apparently, another in central Panamá. Originally described from cultivated material in Europe, purportedly of Guatemalan origin, these palms are now known to be widespread in wet forests throughout the region.

There has been quite a bit of debate over the years regarding the taxonomic status of the populations at the northern and southern extremes of its range, which will appear in most popular works on palms as C. tenella. It is my understanding that both Michael Grayum and Donald Hodel now appear to agree that this name is invalid, and that the morphological characters that “supposedly” separate the two are not constant throughout the species’ range. I fully agree with this conclusion. The traditional view is that those plants with spicate female inflorescences, short apical notches on their leaves and “glossier” leaf laminas are C. tenella, with plants in the central portion of the species’ range (Guatemala and Honduras) being considered textbook C. geonomiformis. It is also my understanding that plants in cultivation in the U.S. and Australia are largely of Belizean and Mexican origin.

Plants grow to ca. 1.85 m tall (6’), although most mature individuals are closer to 1.00 m (3’+) in overall height. They share their habitats with a fair number of other Chamaedorea spp. throughout their range, but are perhaps most closely associated with C. ernesti-augustii and C. oblongata in northern Central America. I have also found them growing in sympatry with C. neurochlamys, C. nationsiana, C. elegans, C. adscendens, C. cf. falcifera, C. schippii and C. tepejilote. In my experience, they tend to be located in shadier pockets within any given forest. While they are most often encountered in tropical forests, they do range up into premontane habitats between 900 and 1,000 m.a.s.l.

I would characterize this palm as very easy to grow, quick to mature to flowering size from seed, and tolerant of more abuse than many other species in the genus with simple leaves. It is a superb pot plant. I would suggest sharp drainage, bright shade and warm, humid conditions as the preferred cultural regimen for this species. It has been saddled with the common name of “necklace palm”, apparently in reference to the similarity between ripe infructescences and strings of black pearls. Some creative soul in the trade HAS to come up with a better moniker for this palm than this one...

While I know that some will disagree, I consider that the finest-looking plants of this species occur on the Guatemalan-Honduran border, where they blend the physical characteristics of both “forms” perfectly. Some individuals show varying degrees of leaf mottling when well-cultivated, and in my mind are strongly reminiscent of certain simple leaf Pinanga spp. I grow both these plants and others from a population on Guatemala’s Caribbean coast, to the exclusion of other populations. If they were to become available in culture, I would also be interested in cultivating the smaller ecotype from southwestern Costa Rica which is depicted as having glossier leaf laminas and more pronounced marginal teeth than plants from further north.

Below, I have attached a series of photos of this species in habitat and seed-grown plants in cultivation at my home. In order to bolster the argument that C. tenella is indeed a junior synonym of C. geonomiformis, for illustrative purposes I’ve selected eastern Guatemalan plants that share the supposed “key” characters of both taxa. The wild plant is, in my opinion, one of the finest individuals I have encountered. Please note backpack alongside for scale. This particular palm has exceptionally long and well-shaped leaves.

Nevertheless, I suspect that my buddy Jason will still disagree with the demise of "tenella".

Ciao,

SJ

[XYZ]

A closeup of the leaves:

[XYZ]

A seed-grown plant from the same population, 32 months old:

[XYZ]

Again, same population, four year-old plant showing very pale leaf mottling:

[RainForestt Robert]

Stone Jaguar,

Thanks for continuing the series on Chamaedoreas.  Lovely photos.  Very informative.  Gives an appreciation for a remarkable genus.

Robert

[Kim]

The habitat photos are always very much appreciated, thank you.  I wonder if you can comment on the ruffled appearance of the leaf in the young pot-grown plant?  I've seen some of this on other undivided leaves such as C. ernestii-augustii.  I see in the later photos the leaves seem to have smoothed out.

(I hope you are writing a book, if you haven't already.)

[XYZ]

Kim:

Thanks. The batch of seedlings that the young female in the photo came from are all noticeably "beefy", as is their mom. I used this plant to illustrate the diversity within even a small population when contrasted with the wild adult. I strongly suspect that the texture and creasing of these youngsters leaves, as well as the speed with which they started flowering is due to a constant but small excess of some nutrient that is producing very mild leaf deformity sans spotting or brown-tipping. The four year-old is growing outside under more normal regimen (= gets fed when I remember to do so, rather than on a fixed schedule), so it has a flat lamina with more normal base color. The very short petioles are from the amount of light that the seedlings get under bright glasshouse culture.

The book's already been written: Donald Hodel's beautiful and definitive monograph "Chamaedorea Palms",  readily available a few mouse clicks away at the IPS bookstore for a reasonable number of dollars. Can't say that I'd ever care to attempt to eclipse it...

Cheerio,

SJ

[aussiearoids]

jolly good show old chap

[jam99]

Jay, thanks a lot! I love your posts!

I have the DH's 2006 monograph "What's new in Chamaedorea" (Jason the Librarian feeds me with Kami papers) but it only briefly mentions the demise of "tenella" pointing to the MG's 2003 publication. So what was the main reason for synonymizing tenella with geonomiformis? How come DH has changed his mind and now agrees with MG?

Please please keep these posts coming. I am sure a lot of us appreciate your willingness to share your knowledge.

Cheers, Jan

[chris.oz]

I have C. tenella and C. geonomiformis, thanks to Jason,  and to be honest one looks like a mini version f the other !

It seems that now the tools are there using DNA to establish clearly the relationships between species,  in a way that was not possible using the appearance of the plant the leaves and the flowers.

Recent DNA studies allow analysis of Date palm varieties to see the relationships within a single species.

Maybe such studies have been done on C. tenella and C. geonomiformis ?    SJ,  has there been much work in molecular studies of Chamaedorea?

BTW SJ, just love the info in your posts !

[Kamipalms]

(stone jaguar @ Aug. 25 2006,01:48)

QUOTE

Nevertheless, I suspect that my buddy Jason will still disagree with the demise of "tenella".

[Kamipalms]

I read about the updated synonyms in the "Chamaedorea" issue of the PSSC Palm Journal but at the time, didn't think too much of it untill realizing the name changes had gone through with the Kew Checklist .

I prepared an email to Michael Grayum including my reasons they should be kept seperate but caught John Dransfield on the net so I run things by him insted.

John suggested I discuss this with Don hodel and over the last couple of months we have discussed this coming to the conclusion that from a taxonomists point of view there wasn't enough evidence to keep the two " forms" as seperate species.

Heres part of what Don and I discussed;

along with some pix to help explain...

I've numbered these plants to help explain whilst using the "previous" species names.

Above and below

Plant's 1 & 2- C.geonomiformis

Plant's 3 & 4 - C.tenella

As a size verses age referance both plants 1 & 3 are from 2001 seed while plants 2 & 4 are from 2003 seed.

I also argued the point that male plants of  "C.tenella"  have a spicate ( singular) inflorescence while C.geonomifromis have a branched inflorescence. This didn't hold up so well as Don said he had seen plants in habit with both spicate and branched inflorescence and no I'm eating my own words cause some of my males are branching....

From there we went on to physical size in every aspect and Don said that they are the outer extreme of the scale when compared but horticulturaly , they are different enough.

[Kamipalms]

We also discussed leaf color  , texture , size toothed margins and so on,

C.geonomiformis

C.tenella

but there is one more point of differance that is still to be investigated and SJ is welcome to add to this;

The differance in flowering charictoristics between the two I've noticed is that with  a male C.tenella all flowers reach anthesis together, droping all pollen at once where as a male C.geonomiformis flowers starting from the tips of the rachis,  changing from green through to yellow  consecutively flowering back up the rachis towards the initial dividing point of the inflorescence.

Now, this observation is with cultivated plants and wheather plants in habit are the same or not.

Don said he would check up on this but I doubt this alone will be enough to satisfy a Taxonomist.

Jason.

[jam99]

Well, they look different to me but it's always difficult to draw a line between possibly two species which at the same time could be members of the same species with great variability among specimens.

Today I noticed Henderson et al. 1995 also thought of tenella as a synonym.