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Author Topic: roland-gosselinii vs rothii  (Read 656 times)
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Robin
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« on: June 30, 2014, 11:00:41 »

Hey y'all

Three years a go my roland-gosselinii sent out a "typical" inflorescence - green with relatively longish, not overly inflated paddles.  This year the inflorescence is different - the paddles are yellowish with bright red blush and they are short.  I wouldn't really bother ('cause it is still freakishly beautiful) but because they look so much more like rothii I have been questioning the validity of the id but also the two separate names.

I have trawled around fcbs.org as well as bromeliad.org.au and resolution is even further away!  There seems to be so much confusion between these two taxa: some say rothii is of hybrid origin (roland-gosselinii x xerographica or even that these is jalisco-monticola involved) whilst others just cant seem to find a differentiation between the two. 

Is rothii just a smaller inflorescence form of roland-gosselinii that occurs in respionse to environmental factors?  Does anyone have a formal description of either so that i can compare them?

I will post pics when I have a chance - still waiting for it to develop a bit further.

Cheers

Robin
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« Reply #1 on: July 04, 2014, 06:34:08 »

They are completely different plants.  The short of it is that T. rothii have fat, inflated paddles that are typically shorter.  T. roland-gosselinii have longer paddles that aren't inflated.  Both have large range of size.  T. r-g has a very huge geographic distribution (some populations have inflos up to ~1m tall, some as short as ~25cm).  The speculation is that T. rothii is of hybrid origin between T. r-g and T. j-m (which would explain the inflated paddles).  I don't know how to tell them apart simply by leaves, vegetative size, etc...it is about distribution and inflorescence.
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Robin
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« Reply #2 on: July 04, 2014, 09:09:49 »

Hey Andy!  I was hoping you would jump in here.  I had a look at your pics on bromeliad.org.au and read the discussion - and then looked at other pics on fcbs etc.  Man, I just can't arrive at a definite answer.  I guess its the same with a lot of plants from other genera - location is what separates them - however if you don't know the origin of the plant it poses a problem.  It is none of those tough ones.  Some taxonomists are more lenient with this than others.  The new/separate taxon however generally have some novelty and is clearly defined in terms of morphometrics.

I do however Q the validity of the separate names - isn't it better to recognise it as one variable taxon? Is there a definite break in the cline?  Or are there intergrades between them?

I would dearly like to see the formal descriptions of each - just what are the differences between the two and is there overlap.

Cheers

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« Reply #3 on: July 04, 2014, 16:44:31 »

Hmmm, didn't realize that my emails and pictures were being published there....
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« Reply #4 on: July 04, 2014, 17:42:48 »

I'll see if I can pull up the descriptions, but still they are very different plants 'in the flesh'.  Can you post pictures of your plant?  The branch length is longer (overall as well as before the paddle even starts), the paddles more narrow, more pointed, less inflated, the primary bracts seem much longer (maybe exaggerated by the longer scape so there are more of them?) on T. r-g.  It is really hard to explain what is much more clear and intuitive in habitat when seeing many, many plants showing the phenotypic range and variability.  The problem with descriptions is that they are rigid and taken with limited samples and usually from limited locations...and they are often not updated to reflect other populations found or any other new evidence.  Frankly, I find many of the discussions had by the Australians as quite entertaining where they draw hard conclusions from such limited data, knowledge, and experience.  Or at least when they argue ad nauseam about things that are unresolvable with the data they have.

On further reflection (and study on the subject), I think the hybrid origin hypothesis put forward by Gardner has a good chance to prove true.  It is hard to draw the lines on species anyways, but when adding the wrinkle of distant hybrid origin and gene flow that has continued it is going to be messy.  But everything in this case is pointing in the right direction.  Part of the problem about the hybrid origin is that the parents may no longer be in close physical proximity (or even both extant).  Or the opposite problem, if the speciation event is still in mid-process...without a new species stabilizing or possibly just being an intermediary that is providing a means for gene flow between the two species.  So many scenarios.  And add the habitat destruction and fragmentation, we have no way of even guessing where evolution is going and what will stabilize and succeed.
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« Reply #5 on: July 05, 2014, 14:19:45 »

I always wonder how many of those hard to find in the wild broms that we have really are species or just as you say "the speciation event is still in mid-process". I read one of Foster's books about collecting in Brazil and he on occasion collected the only plant in sight or from very limited availability.
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« Reply #6 on: July 05, 2014, 16:51:42 »

It is hard to say.  But everything by definition is in 'mid-process'...either expanding, diversifying, contracting, hybridizing, introgressing, suffering from a genetic bottleneck.  Life is a continuing process.  The only thing that isn't are the extinct species.  The status of the Bromelioideae subfamily is such a taxonomic disaster because they are so young that there is a lot of flux as the different groups and species are diverging (and probably still swapping some genes).  Was it (and is it still the case?) that Ae. orlandiana or Ae. correai-aroujei was only known from the collection of a single plant? The arguments about the genus Aechmea is one of my favorites...it is by definition and 'academic' argument (sort of).  Once you remove the groups that make it paraphyletic/polyphyletic it is pure personal philosophy whether Portea should retain generic status or should be subsumed into Aechmea (along with the other cases).  Neither Leme who says Portea is invalid nor the other taxonomists are 'wrong' as long as they are self-consistent and follow their definition of what it means to be a genus.  There is no hard line that 100% determines whether something is its own genus or not.  Just like with many species, the designation of the name is an artificial creation that the plants don't care about!  It is only useful to (and for) humans.  Of course I'm not arguing that everything is the same species like some people in the past on the forum (or was that way back in GW?).

But we have to realize when it is worth fighting or not.  Which comes back to Robin's question about T. rothii and T. roland-gossselinii.  Clearly they are closely related.  It is a safe bet to say there is still gene swapping going on between the two (as well as with other species that they each grow with locally).  If we go by the way we have traditionally treated the T. fasciculata complex, from a 10 meter view they are the same plant--(just like when we see a grayish-green rosette Tillandsia with branched inflorescence with colorful paddles we instinctively/reflexively call them T. fasciculata.  If we care to take a closer look we can find differences that have at least somewhat of a geographic boundary.  Is it possible to divide another species or two out of T. roland-gosselinii?  Actually more likely than most people would probably feel comfortable with.  There are monster-sized plants down south that probably have been intrograding with other species which makes them much larger and almost surely genetically unique.  Does anyone really care, no.  Phenotypically they are just a larger form of T. roland-gosselinii!  That is why no one has really tackled the complexes of T. fasciculata, T. capitata, and others (T. ionantha).  The T. fasciculata complex has been chipped away at......but it is somewhat useless until someone does a complete and systematic look at it (hint, hint, hint).
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Gnarly dude!


« Reply #7 on: July 06, 2014, 00:17:54 »

Perfect timing for this post, let's see if you can guess which one is the roland-gosselinii and which is the rothii?
And I'll bet you're wrong.

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« Reply #8 on: July 06, 2014, 00:50:45 »

I'll take a stab...T. rothii in the middle flanked by a pair of T. rolands?  Based solely on leaf width.  But even the one in the center has fairly narrow leaves for a T. rothii.
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« Reply #9 on: July 06, 2014, 12:57:30 »

Left and middle =rothii, right one is roland-gosselinii.
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« Reply #10 on: July 06, 2014, 19:51:53 »

Well, not too bad...2 out of 3.  Could have been a lot worse.  Although I should have guessed that you would have more T. rothii as it is much more common in cultivation than T. roland-gosselinii.
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« Reply #11 on: July 06, 2014, 23:01:40 »

Okay processed some pictures (I forgot how much of a pain it was to upload into photobucket first!).  I'll start with T. rothii.

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And a few of T. roland-gosselinii:

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I should have some more photos.  If I come across them I'll process and post them.
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