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Message |
    
Hellenophile
| | Posted on Saturday, January 12, 2008 - 02:39 pm EST : |   
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Not a lot in flower at the moment so a few pictures of leaves to illustrate the variety that can be found. This subspecies is restricted to Crete, especially in the white mountains and near Platanias and Malaxa.
Hellenophile
- Surrey,
Zone "?"
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Terryk
 Supporting Member
My Weather
My Garden
My Time
| | Posted on Saturday, January 12, 2008 - 03:04 pm EST : |
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Well I can see why you have a glasshouse full of graecum! I first thought you were posting photos in black and white but see they are not.
I can't pick a favorite, they are all great.
Terryk
- NY,
Zone "6"
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Growit
Supporting Member
My Favorite Photo
My Weather
My Time
| | Posted on Saturday, January 12, 2008 - 03:05 pm EST : |
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Beautifully photographed. Really shows off the leaf patterns. I much prefer the leaves to the flowers of most cyclamen.
Growit
- Hampshire,
Zone "8/9"
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Tony_willis
| | Posted on Sunday, January 13, 2008 - 11:15 am EST : |
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here is my ssp candicum.Each leaf is about 3 inches long and the plant is completly unlike any other in my collection
Tony_willis
- Lancashire,
Zone "7"
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Matthias
Supporting Member
| | Posted on Sunday, January 13, 2008 - 02:40 pm EST : |
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Melvyn, these leaves really are breathtaking! Numbers 4 and 5 would be my favourites.
Do you know of any theories, which evolutionary advantage the "silver" shields or veins could have in Cyclamen? In my garden I have observed in herderifolium that the tissues under silvery parts of the leaves are more resistant to frost damage than the pure green parts on the same leaf.
Maybe the air bubbles between the upper and lower cell layers acts as a kind of nano-glasshouse???
Matthias
- South Germany,
Zone "7"
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Hellenophile
| | Posted on Wednesday, January 16, 2008 - 03:47 pm EST : |
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Hello Matthias, No I dont have any theories but having observed Cyclamen graecum at Monte Smith on Rhodes and at Pilos in the Peloponnese (both places where plants grow in the open as well as under the shelter of mature trees close by) it is very clear that the plants growing in the open, exposed to full sun, often have silvery leaves whereas those growing under the nearby trees do not.
Hellenophile
- Surrey,
Zone "?"
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Matthias
Supporting Member
| | Posted on Wednesday, January 16, 2008 - 04:26 pm EST : |
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Yes, that is what I have very often observed in Cyclamen purpurascens in North Italy. The hotter and sunnier the location the higher the percentage of silvery leaves. One can almost reliably predict silver leaves for certain local climates and situations. What appears silver to our eye is the effect of strong reflection of the whole spectrum of the sunlight = very little absorption/energy input/heating/burning of the tissue. Leaves that appear green absorb red and blue light which means much more energy etc... input.
More open situations also offer less protection from occasional light frost and also here a sliver coating seems to be favourable.
Matthias
- South Germany,
Zone "7"
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Loretta
Supporting Member
| | Posted on Friday, January 18, 2008 - 10:04 am EST : |
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Beautiful leaves. Beautiful photographs. Really makes a nice photo series. Such great texture.
Loretta
- NJ,
Zone "6"
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Jan_bravenboer
| | Posted on Saturday, January 19, 2008 - 02:28 am EST : |
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Yes Matthias, that's what I thought as well. However I know many mountains in the Lake Garda area where you will not find a single silver leaved C. purpurascens, not even when it is a very hot place. Even on the top of many mountains (and in their valleys) around Lake Garda you sometimes find not a single silver leaved one.
Once I thought that closer to Lake Garda is warmer and the chance to find silver leaved plants would be bigger. On my last trip I found hundreds of silver leaved plants, far away from the hot Lake Garda area, on a cool and wet location very close to a brook, in total shade. What is your explanation for this ? I think there must be more than temperature.
Regards,
Jan
Jan_bravenboer
- -,
Zone "7a"
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Berthold
| | Posted on Saturday, January 19, 2008 - 07:31 am EST : |
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What about this one? Is it a candicum too?
Berthold
- NRW, Germany,
Zone "8a"
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Matthias
Supporting Member
| | Posted on Saturday, January 19, 2008 - 10:27 am EST : |
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Jan, I agree that the situation in the wild can be very puzzling. And I also totally agree if you say we should be careful with finding and giving easy answers. You will have noticed in my previous post that I was talking about my observations of higher percentages of leaf patterns depending on local climate conditions. In a vast mountainous area in north Italy east of Monte Baldo I regularly found almost no silver leaves in the beech woods in the higher locations above 500 metres while the percentage of silver leaf plants was over 50 % every time I went down into the many different valleys in that area.
Absolutely the same distribution pattern can be observed in a high mountain range in Istria: Dull green patterns on the mountain and as soon as you come down there are (can be!) high percentages of silver leaves in some places, but not everywhere.
The same distribution pattern can easily be observed on Monte San Salvatore in southern Switzerland. Absolutely no silver leaves in the summit region but as you come down there are high percentages of silver leaves in some places, but again, not everywhere.
In all cases in deep valleys or at the foot of a mountain where I found silver leaved purpurascens the sites where below partly barren, steep limestone cliffs. Let us for a minute consider evolutionary processes: Organisms adapt to environments, sometimes very fast, sometimes slowly if pressure is not very high. The age and comparatively little variation in the genus Cyclamen suggest that the genus is good enough adapted to a Mediterranean and subMediterranean climate in shaded habitats. Selection pressure must have increased strongly during the ice ages which lasted about one million years and during which woodlands were absent in the more northerly parts of the distribution range of Cyclamen. "Suddenly" (for such an old genus) selection pressure became high or even very high in many areas and only silver leaf forms with their high reflection capacity were able to survive in those totally exposed locations: It was a matter of adapt or go extinct.
I believe that in those cyclamen populations that survived the ice ages on these open habitats and unwooded cliffs in full sun the silver leaves became at least the majority if not the rule. When the woodlands gradually returned about 10.000 years ago the cyclamen had to readapt to shade and turned predominantly green. But the disposition for silver leaves is still present in the general gene pool (it is present in the whole genus, as we all know). So wherever today cyclamen grow in open places AND the specific local gene pool offers the material for silver leaves these may develop.
What, in your example, is a cool, wet and shady little canyon or valley today may 10.000 years ago have been a sunny, hot cliff and the local gene pool may still be set for the production of high percentages of silver leaved plants.
Also remember that seeds can be washed away (even today) from sunny places into shady valleys thus “exporting” local adaptations to different habitats.
But I’m convinced that silver leaves are not well adapted to deep shade: They can survive but in the long run (longer than our lives) the “stronger” green forms will take over.
I’m far from saying that these are the only explanations or that they are the only true explanations for the striking distribution patterns, but to me they appear at least plausible. If it does not go beyond the intentions of this forum a broader discussion of the topic would be very welcome ...
Matthias
- South Germany,
Zone "7"
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Berthold
| | Posted on Saturday, January 19, 2008 - 12:00 pm EST : |
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Matthias, are there any measurements of the light reflection rate of silver leaves compared with green leaves? The silver colour of the leave dosn't mean necessarily a higher reflection.
Greetings Berthold
Berthold
- NRW, Germany,
Zone "8a"
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Jan_bravenboer
| | Posted on Saturday, January 19, 2008 - 01:41 pm EST : |
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I agree Matthias. Will travel to the Lake Garda area again this year, this time the first two weeks of September. I always visited the area the end of June, want to search for forma album this year.
Regards,
Jan
Jan_bravenboer
- -,
Zone "7a"
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Matthias
Supporting Member
| | Posted on Saturday, January 19, 2008 - 01:58 pm EST : |
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Berthold, silver is a slightly greyed white - agreed? The sunlight is white and is composed basically of red, green and blue - agreed? A white surface is white because it reflects almost all visible light: red, green, blue - agreed? Newly fallen snow reflects up to 98% of the incoming white light.
A green surface is green because it reflects most the green light component while red and blue is largely absorbed. Photosynthesis has two maxima in blue and red. If there is an excess of sunlight on the leaves (cyclamen have typical shade leaves) this will inevitably lead to some kind of damage - at least photoinhibition which means that photosynthesis comes to a halt.
Every camera and also our eyes measure the much higher light reflection rates of a silver surface compared with a dull green one.
I think the reflection is caused at the inner cell surface of the one-cell-layer cutile which is slightly detached from the mesophyll. Interestingly the silver impression vanishes during periods of frost.
Matthias
- South Germany,
Zone "7"
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