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Carol23
| | Posted on Thursday, November 16, 2006 - 09:52 am EST : |   
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Berthold, wouldn't there have been experiments to prove or disprove this ?
A deep, large clay pot planted with one each of hederifolium, cilicium, coum, mirabile and graecum - all planted at soil level might make or break the theory. There would be no additional organic matter added. What time frame would be necessary?
Since we cannot grow graecum in the garden here, an outdoor experiment is impossible. I've observed large coum and hederifolium tubers right at the surface many years after planting in the garden.
Berthold, have you noticed your graecum tubers digging themselve deeper in your garden?
Carol23
- Southeastern PA,
Zone "6B"
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Geoforce
My Weather
| | Posted on Thursday, November 16, 2006 - 10:09 am EST : |
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Carol, A possible alternative to the contractile roots hypothesis is the fact that Tony says this is a routinely plowed area. Perhaps the plow turned the tubers to a deeper location and they stayed there. A rebuttal to this option, however, would be if the tubers in the burnt-over area were also at the same depth despite not having been plowed. Still, I think your experiment would be a valid investigation to pursue.
Geoforce
- Pennsylvania,
Zone "USDA 7a"
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Berthold
| | Posted on Thursday, November 16, 2006 - 10:52 am EST : |
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Carol, I did it myself because I am a little afraid of frost. There are other Cyclamen species without this strong roots growing very deep sometimes. How do they manage to dig themselves?
Berthold
- NRW, Germany,
Zone "8a"
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Guff
| | Posted on Thursday, November 16, 2006 - 12:20 pm EST : |
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Tony_willis, super pictures.
Guff
- NY,
Zone "?"
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Jgwoodard
My Garden
| | Posted on Thursday, November 16, 2006 - 01:07 pm EST : |
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Years ago I was surprised to find Erythronium americanum with bulbs around 30 cm (12 inches) underground in seemingly dense, compacted soil. It amazed me to find them at such depths considering how tiny the bulbs are. That's how I first learned about contractile root hypotheses, but there is no way to know if the bulbs I found 12 inches down were there primarily from the pull of roots or basic growth into those areas. These bulbs are of course connected by a series of roots and bulblets and connective points (they almost behave as if stoloniferous, like some other members of the lily family). In this way they produce new growth points relatively far away from the original... up, down, or sideways. Contractile roots represent just one factor in the movement of such plants.
For a plant like C. graecum the repeated swelling and dessication of thick roots during times of moisture and drought, combined with similar changes in the soil itself, could certainly create space for movement through soil (therefore potentially digging themselves deeper), but it seems like it could take many years depending on the substrate? For plants on slopes it would be helpful just to anchor the plants and protect against erosion of soil layers.
Jgwoodard
- TN,
Zone "7"
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Geoforce
My Weather
| | Posted on Thursday, November 16, 2006 - 01:41 pm EST : |
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Yes Joseph, I too when young decided to move a few Erythronium into my garden. After digging down over 18" in a sandy leafmold soil, I decided that they could not be safely moved anyway unless in a dormant state, and then how was I to find them at that depth. Needless to say, I gave up on moving them.
Geoforce
- Pennsylvania,
Zone "USDA 7a"
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Matthias
| | Posted on Thursday, November 16, 2006 - 02:04 pm EST : |
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Tiny tubers of very young cyclamen seedlings are always very close to the surface. The seeds germinate on or slightly below the surface and are normally covered by leaves and other material. Adult tubers of e.g. C. purpurascens or C. repandum, on the other hand can be found up to 30 cm below the surface and even below rocks. C. purpurascens forms what is called floral trunks (why floral? they carry vegetation points for both leaves and flowers!) while C. repandum sends both leaves and flowers up from 30 cm below the soil surface. In both cases the tubers are not only covered by organic material that falls in the autumn, but they can sit very deeply in the mineral horizon of the soil. This clearly indicates that the tubers move or are moved downwards. It is interesting to note that C. purpurascens in northern Italy can "behave" very differently: in the high mountains the tubers are buried very deeply and are thus protected from severe cold, while a few kilometers further in a warmer habitat all tubers sit very closely to the surface.
Joseph, I have very much sympathy for your explanation with desicating and swelling tubers and resulting hollow spaces in the soil and want to carry on from here: This could actually be the main motor for the downward movement.
On the other hand we all observe, that hederifolium is often and in some areas regularly very close to the surface or even exposed: C. hederifolium has its roots on the upper surface of the tuber and so the roots can not keep the tuber down, when it shrivels in summer.
So I do not think, the tubers are actively pulled down by the roots, but the are held in place while the tuber shrivels and the hollow space on top of the tuber is filled with soil in the wet winter months. Then the tuber swells again and expands in all directions: downward, left, right and upward, a few millimeters each year. It is the roots that always hold it at its lowest possible position.
Matthias
- Southern Germany,
Zone "7"
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Jgwoodard
My Garden
| | Posted on Thursday, November 16, 2006 - 03:03 pm EST : |
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George I totally understand your conclusion, but you should know that those plants are still in my garden and have created little colonies, and they were moved in flower! :-) I treat such matters in a similar manner as careful archeaologists treat a delicate excavation. It is indeed possible but takes a very delicate approach from the beginning and is certainly easiest on slopes.
Jgwoodard
- TN,
Zone "7"
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Berthold
| | Posted on Thursday, November 16, 2006 - 04:45 pm EST : |
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Matthias and Joseph, I see it in the same way. So we should decide that's it.
Berthold
Berthold
- NRW, Germany,
Zone "8a"
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Tony_willis
| | Posted on Thursday, November 16, 2006 - 05:52 pm EST : |
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Oh the passion and controversy of gardening.I might have known the question of depth of tubers would arise and so whilst in Greece I dug down the side of a smallish plant in the burnt area. The soil was quite stone free and I got to eight inches without meeting the tuber.
The ones in the olive grove are not disturbed by the ploughing and I would suggest that they were there before this was started.They would then be under the plough depth. I think the only answer to this question will be when we teach the plants to talk.
At these depths and given that the roots then go on downwards for many inches the plants do not dessicate in summer as there is always some residual moisture
In Turkey I know of a forest road with high banks that are constantly erroding.It is easy to find plants hanging upside down by their roots and thriving.
Here is a picture of another plant I found in Turkey with the tuber out of the ground.
I must also say that I disagree with Berthold in that C. graecum often grows in fire areas. These fires sweep across large areas of both Greece and Turkey in the summer and it is this dry habitat that often contains these plants
Tony_willis
- Lancashire,
Zone "7"
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Berthold
| | Posted on Thursday, November 16, 2006 - 08:05 pm EST : |
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Tony, I agree but I think these dry areas are not necessarily fire areas. Your olive grove isn't.
Your last photo from Turkey with this beautiful leaves especially shows what anchor roots could be good for.
Berthold
Berthold
- NRW, Germany,
Zone "8a"
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Terryk
My Weather
My Garden
My Time
| | Posted on Thursday, November 16, 2006 - 09:54 pm EST : |
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I can't contribute much to the discussion, other than to say, it is great reading and learning from everyone.
Terryk
- NY,
Zone "6"
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Tony_willis
| | Posted on Saturday, November 18, 2006 - 04:44 pm EST : |
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Berthold
I think we are at cross purposes here. What I was trying to say was that the graecum grow across a wide range of habitats,but always much drier than hederifolium.Those areas that are not cultivated are often where the fires occur in the maquis.On the Langada Pass near Sparti in the Pelopennese there was a huge fire about 5 years ago that burnt several square miles of pine forest and a similar one on the Dacta penisular in Turkey neither of which of course contain cyclamen. It is a hazard of the mediterranean just like say California which has a similar climate
Where is NRW in Germany ?
Tony_willis
- Lancashire,
Zone "7"
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