callosum or barbatum?

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PaphMadMan

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...
Thank you all for your input. I posted the question to highlight the problem of species/nat hybrid/artificial hybrid being more widespread than just in the cochlo group which seems to get all the bad publicity, while there is a bigger problem in the most extensively hybridized group, which would call into question nearly every name from Maudiae onwards:evil::rollhappy:

I would add that even a "pure" species, traceable back to specific well documented and characterized collected plants, could be unrecognizable after a few generations of selective breeding. And in virtually all cases we have only the most recent grower's word for what it should be.
 

TyroneGenade

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Tyrone,

Both first and second editions of Cribb's The Genus Paphiopedilum agree on the separation of barbatum and callosum on the basis of petal stance, petal length, and dorsal sepal shape. Excellent drawings/photos of these differences in each edition.

Tom, can you share the diagnostic criteria here? What are the differences in petal stance etc... as Cribb describes them?

Thanks
 

tomkalina

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Tyrone,

P. callosum = "Petals strongly sigmoid, deflexed, usually more than 5 cm long;
dorsal sepal large, often apparently ob-ovate, usually more
than 5 cm wide."

P. barbatum= "Petals linear,spreading,less than 5 cm long; dorsal sepal ovate,
usually less than 5cm wide."

Not much to go by, but apparently enough for Cribb to separate them.
 

Rick

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Tyrone,

P. callosum = "Petals strongly sigmoid, deflexed, usually more than 5 cm long;
dorsal sepal large, often apparently ob-ovate, usually more
than 5 cm wide."

P. barbatum= "Petals linear,spreading,less than 5 cm long; dorsal sepal ovate,
usually less than 5cm wide."

Not much to go by, but apparently enough for Cribb to separate them.

But on pg 334 of his second editon:

"With a range of variation that is virtually continuous between the extremes of northern Thailand P. callosum and southern Malaysia P barbatum, it might seem reasonable to consider them conspecific. However, the extremes are readily distinguishable and whilst realizing the biological reality, it would undoubtedly cause considerable nomenclature confusion to reduce P. callosum into the synonymy of P. barbatum, or even treat it as a subspecies or variety of the later. Recognizing P callosum and P barbatum as specifically distinct is a compromise that is nomenclaturally and horticulturally satisfactory."

So the systematic characteristics probably are good for identifying the extremes in the two species, but not for splitting out the contiguous intergrades in the Malay peninsula.
 

gonewild

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So unless you know where they were collected you can't be sure what they are. In that case it probably makes no difference, just choose whichever name you like best.
 

tomkalina

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Wow! You guys have lost me on this one. Given the key, what floral morphology specific to barbatum do you see in this callosum?
 

Rick

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Yes, unfortunately (along with Cribb's key) it's all we have.


The key is all messed up.

On page 337, Type description of P callosum var. sublaeve:

Dorsal sepal 3.4 - 4.2cm long and 3.0 - 4.1cm wide, shorter broader and less sigmoid petals (than nominal north Thai variety).

On page 330, Type description of P barbatum:
Dorsal sepal 3.9 - 5.0 cm long, 4.3 - 5.5cm wide.

His Type description of the North Thai P. callosum does have dorsal sepal dimensions going to 6cm.

So if you have flowers from plants originating from the Malay peninsula then the smaller ones can just as easily be a callosum (var sublaeve) than a barbatum.

There are also light and dark barbatum so "darkness" is not characteristic of the species (although the darker forms are usually selected for).
 

Rick

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One wonders why he (Cribb), after taking all these things into consideration decided to separate them.....

"it would undoubtedly cause considerable nomenclature confusion to reduce P. callosum into the synonymy of P. barbatum".

Sounds like he was trying to save us splitters from ourselves.:eek:
 

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