An another questio for you-

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stefan m.
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An another questio for you-

Post by stefan m. »

This is as mind boggling as it gets to me- and yet simple. probably scholarly articles exist but...
What is the reason behind the opuntias ( and consoleas and others)' cladode weird flat shape?
Is it the sun? The wind? Pollination? defense? I havent come across a straight answer for this one.
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ElieEstephane
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Re: An another questio for you-

Post by ElieEstephane »

Ease of propagation comes to mind but that's probably not it.
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stefan m.
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Re: An another questio for you-

Post by stefan m. »

Not likely, cylindropuntia is better at it. Youd think that being flat would help you have the advantage being fallen on the ground, cover a large surface area means more sunlight energy absorbed... but thats circumstantial at best. It does apply for photvoltaic panels however.. And even though plants do absorb energy from the sun, the rule for panels is "bent at the equivalent geographic latitude angle toward the sun(90 deg), so that the max solar energy is absorbed" and "more surface area, more energy absorbed ...". But we all know opuntia plants are too chaotic in their growth patterns for that to be true. Maybe for consolea though. But again, circumstantial.. Maybe the plants face side with least sun exposure, maybe are self shading(like dracaenas...)
Its not like someone bothered to measure each pads individual angle sun facing or otherwise...
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TimN
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Re: An another questio for you-

Post by TimN »

I don't have the real answer, but I know that Opuntias are considered more "primitive" plants, less developed. To me, the shape doesn't make much sense, with the thin, wide shape instead of globular they don't get the advantage of less surface area per unit of mass. I"m not an Opuntiod expert, but I wonder what the split is between cladode or pad species and the cylindrical species. Are there more species with pads or not. My stab in the dark guess is that species with pads are in the minority.
Disclaimer: I'm in sunny Arizona, so any advice I give may not apply in your circumstances.

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stefan m.
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Re: An another questio for you-

Post by stefan m. »

Yet somehow they are spread from canada to galapgos... and invaded every other continent (except antartica).
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Re: An another questio for you-

Post by DaveW »

Opuntia's like all cacti, except a Rhipsalis in Africa, are native to the America's and were introduced by man to the "Old World" and elsewhere. In most cases the Spanish missionaries originally spread them to the Old World on their return for their fruit etc. Opuntia ficus-indica is sometimes called "Mission Fig" since it was set at the Spanish Missions in the America's as a fruit plant. The Spanish evidently also introduced O. ficus-indica to the USA from Mexico.

"One of these is Opuntia ficus-indica, which was introduced around 1500 from Mexico (its exact native distribution is not known) into Spain and, later, throughout the Mediterranean ... The plants spread vegetatively by the pads although seedlings are also produced and play a role in establishment and spread of the species."

See:-

http://tephro.com/index.php/the-journal ... html?id=44

https://davesgarden.com/guides/articles/view/4238

http://www.amjbot.org/content/91/11/1915.full

The original habitat of what were considered useful plants by native populations is often lost in obscurity since they were gradually moved around the country and eventually to other countries before any scientific recording of their original habitats and distribution took place. Another example is Trichocereus peruvianus and T. pachanoi, grown for their hallucinogenetic properties and so spread far from their original habitat by man.
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ElieEstephane
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Re: An another questio for you-

Post by ElieEstephane »

This article has opuntia history at the bottom
https://www.dbg.org/blog/evolutionary-history-cactus
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stefan m.
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Re: An another questio for you-

Post by stefan m. »

As interesting as that was, and explains and confirms half of what i know, still does not answer why the opuntias and the like are so weird. I understand pretty much everything except that. I dont really see the cause and effect connection for the flat pads. And we all know plants dont do things for the "lulz". Everything has a reason, especially with cacti, while weird just by themselves, a pattern to their appearance is noticeable, with the exception of those few related genuses.
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stefan m.
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Re: An another questio for you-

Post by stefan m. »

Only theory i got is that the common ancestor of all the opuntias was a crested plant, and somehow managed to pass on genes or something. But thats far fetched as it gets...
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Re: An another questio for you-

Post by DaveW »

I think Darwin got the wording wrong, it's not so much survival of the fittest, but elimination of the unfittest, leaving any variation not actually detrimental. Some tell me that means the same, but I think it is a different emphasis. Any mutation that does not prevent the plant from breeding and passing on it's genes before it dies survives. Darwin's Natural Selection alone works too slowly, therefore we now know mutation plays a big part and whilst anything that enhances survival and breeding survives, so does any mutation that is not actually detrimental to it.

The more severe the habitat the closer to the ideal configuration for it are. As an example take cold seas, most of the fish are similar shapes and colours, but in kinder warm waters and coral reefs the variation in colour and shape is tremendous, since they are not under the same survival pressure, therefore any mutation not detrimental to it passing on it's genes before it dies survives.

That means the flat pads on Opuntia's need not have a purpose, only be a mutation that does not affect their survival. In some ways that can be an advantage since ultra specialisation for a habitat, or pollinator, can be a literal dead end if habitat conditions change. Whereas a number of surviving variations which were not optimum for the original habitat could then produce one more suited to it if conditions change.

Anyway that's my theory why you find greater diversity of forms in one habitat to another, since if it was survival of the fittest there would eventually only be one form in every habitat.
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stefan m.
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Re: An another questio for you-

Post by stefan m. »

Except opuntia pretty much has entered almost every habitat available, from the "potato shaped " opuntia fragilis, to the colorful desert opuntia fragilis, to the oddball braisliopuntia brasilolensis and the almost cylindrical tiny opuntia aurantica.
So, you said that it doesnt need to be a useful trait to survive, so just not harmful. But its clearly a trait has opuntiads pretty much the most widespread cacti in their native habitat, and also on the planet.
My only assertion is that clearly weird cladode plants are doing something right, because if the flats pads were not beneficial in some way, theyd have been confined to only a relatively small area(eg to be widespread as the similar tribes like pachycereae, limited to a few states (south-west usa to mid mexico and central america ).
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Re: An another questio for you-

Post by esp_imaging »

I'd assume it's at least partly to increase the surface area for photosynthesis. I think the most xeric opuntiods tend to have more-or less spherical or short cylindrical cladodes, to minimise tha ratio of surface are to volume. Opuntias with more flattened (and increasingly thinner pads, Brasiliopuntia springs to mind) are presumbaly adapted to areas where drought periods are less extreme.
Apparently pad orientation tends towards maximising the ability to photosynthesise (and presumably there can be a balance with other factors, so a tree-like plant, say a Nopalea, with a distinct trunk, must have roughly the same number of cladodes on its shadier side as its sunny side, otherwise it would topple over).

From https://www.botgard.ucla.edu/cladode-or-phylloclade/ -
"Research on cactus cladodes has shown that the pads (cladodes) for a plant tend to become oriented so as to maximize PFD interception by the plant canopy over the course of the year. So it is found that optimal cladode orientation is different at different latitude and on different slopes. Earlier interpretations hypothesized that the pads were oriented instead to minimize midday solar heating during summer, but that interpretation apparently is incorrect and is basically a secondary result or benefit of maximizing light interception and, hence, total biomass accumulation."
Last edited by esp_imaging on Fri Dec 22, 2017 1:59 am, edited 1 time in total.
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Re: An another questio for you-

Post by esp_imaging »

TimN wrote:I don't have the real answer, but I know that Opuntias are considered more "primitive" plants, less developed. To me, the shape doesn't make much sense, with the thin, wide shape instead of globular they don't get the advantage of less surface area per unit of mass. I"m not an Opuntiod expert, but I wonder what the split is between cladode or pad species and the cylindrical species. Are there more species with pads or not. My stab in the dark guess is that species with pads are in the minority.
I think regarding them as "primitive" as you describe misses an important factor. "Primitive" refers to closeness to an original ancestor, rather than meaning "sub-optimally adapted to their environment". The fact that they survive, and thrive, demonstrates that they are well adapted to their environment. So they don't need to be "advanced".
I'd guess that the flattened cladode is an adaption to posess some of the larger surface area that benefits plants with large leaves, but in a succulent, and still very drought resistant form. So opuntias with large pads are a very well adapted to occupying an "evergreen shrub" (and small pad forms as "evergreen cushion") ecological niche in low-water environments. The fact that they are not tiny geophytes or tall columnar trees or small barrels does not mean they are not successful and extremely well adapted to their particular niche.
I'd guess that flattened cladodes are more predominant in higher rainfall areas than cylindrical forms, or else where there are other specific environmental factors (can't think of any..) favouring a flattened cladode shape.
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stefan m.
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Re: An another questio for you-

Post by stefan m. »

So, somebody did measure how the pads are growing regarding conditions...
Thanks esp_imaging.
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Re: An another questio for you-

Post by DaveW »

Yes we had the "Primitive" - "Advanced" argument in a cactus society I was in years ago and decided "Greater or Lesser Specialisation" for the habitat were better terms. Extreme specialisation can be a dead end in ev0lution should climate or pollinator change, then the species would be wiped out. Whereas lesser specialisation may mean a species can adapt mere easily to the new conditions and survive.

One reason mankind has spread around the world into so many different habitats is said to be because we are not an over specialised animal, therefore can adapt to many different environments because we are a "jack of all trades, but master of none". Many other creatures are probably better suited to the particular environment we live in than we are.
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