The Tropical Fruit Forum
Citrus => Citrus General Discussion => Topic started by: kumin on February 03, 2020, 10:51:44 AM
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I've noticed a twig with 3 consecutive sets of paired thorns on a F2 citrange specimen. Some distant Citrus relatives are armed with paired thorns,(Hesperethusa crenulata on occasion) I'm not certain how common this feature is among Citrus. Hesperethusa's compound leaves have a resemblance to Poncirus, although fruits and bark are quite different.
I see there's an additional pair at the base of the scion.
(https://i.postimg.cc/PLJcYJWZ/Feb-1-2020-Conestoga-11-outdoors-on-Poncirus.jpg) (https://postimg.cc/PLJcYJWZ)
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The only true citrus with paired thorns is C. inodora which is found in a limited area of Queensland, Australia.
See http://www.homecitrusgrowers.co.uk/australia2016/australia2016inodora.html (http://www.homecitrusgrowers.co.uk/australia2016/australia2016inodora.html)
This species does hybridise very easily and the resulting seedlings often have the paired thorns.
However, I've never noticed any twin thorns on Poncirus or its trifoliate hybrids.
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Great post Citrange.
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There are additional grafted scions of this clone showing the same thorn twinning. Apparently it's an identifying characteristic of Conestoga #11.
Another twin thorn #11 scion.
(https://i.postimg.cc/PpyLFdcT/Conestoga-11-twin-thorns.jpg) (https://postimg.cc/PpyLFdcT)
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Years back Citrus Joe gave me a young seedling that had twin thorns. I can't remember the name of the variety. I no longer have it. All I remember was that it was an Australian cultivar.
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Do you have any other information about the variety Conestoga #11?
I can find no references to it and it is not listed in the CVC at Riverside.
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Millet *citrus inodora.
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citrange,
Conestoga is the name given to a number of cold hardy F2 citrange survivors from a trial in the winter of 2018-2019 in the southeastern part of Pennsylvania, USA. None of these have fruited at present, so naming them may be premature.
Their only claim to fame is having survived -11.8 deg. F. (-24.3 C) in January of 2019 without protection against the winter temperatures. Except for cold hardiness, little is known about their characteristics.
The 12 surviving plants came from an initial population of 20,000 C-35 citrange seedlings of which 85% were nucellar seedlings. This trial is still in it's relatively early stages.
(https://i.postimg.cc/vg7wfDVQ/IMG-20190131-071759.jpg) (https://postimg.cc/vg7wfDVQ)
(https://i.postimg.cc/nMFjwmhf/IMG-20190309-063619.jpg) (https://postimg.cc/nMFjwmhf)
(https://i.postimg.cc/RNq3vztP/IMG-20190504-183036.jpg) (https://postimg.cc/RNq3vztP)
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Thanks for the information and photos.
I remember reading about this experiment and thinking that it's good someone has the time, facilities and interest to carry it out over several years.
I know modern genetics suggests different characteristics are separately coded, so that it is theoretically possible that 'hardiness' is combined with 'deliciousness' in a hybrid.
But another way of looking at it is to consider an offspring being anywhere along a line between the parents with their characteristics gradually changing from one to the other.
Using this model, an offspring could sometimes be virtually identical to one of the parents.
So, I fear your surviving plants may be indistinguishable from the Poncirus parent.
Let's hope this experiment proves me wrong!
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citrange,
I'm fairly close to agreement with your premise. By virtue of selecting for the extreme cold hardy genetics found in Poncirus, there is also by necessity, a similar selection against many desirable Citrus genes. The hybrids selected do, however, have genetic diversity amongst them. There are monofoliate, as well as nearly thornless individuals in the hardy population. The critical question is which Citrus genes are still present in selected breeding stock.
By maintaining the hardiest population as breeding stock, the cost and complexity of overwintering the plants can be lowered.
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One never knows about seedlings.. A chance lemon seed planted in Los Angles, California in 1858 by Mr. Thomas Garey, turned out to be one of the world's biggest success stories....the Eureka Lemon. Garey's seedling quickly became instantly loved because of its precocity, thornlessness, and everbearing nature.
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In a strict sense this Conestoga population should not be called F2, since it was produced from seeds of open pollinated flowers of C35 citrange.
We probably will never know what kind of other citruses were flowering nearby.
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You are correct, Ilya. The seed orchard being nearly 3,000 miles away, there's no way to be certain of the configuration of the parent tree layout. The one likelihood is that the pollen originated from trees blooming at the same time.
Having no connection to the industry, any other conjecture would be idle speculation.
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Numerous twin thorns on Poncirus
(https://i.postimg.cc/sBNSCpTQ/Poncirus-twin-thorns.jpg) (https://postimg.cc/sBNSCpTQ)
Today, during thorn removal on Poncirus in preparation for future grafting, I noticed many twin Poncirus thorns. A few observations that stood out:
1. One of the thorns tends to be longer.
2. There is only one bud despite two thorns.
3. A few of the thorns have several bud scales near the sharp point.
4. A few have partially developed onto short branches.
5. I believe the second thorns are imperfect branches that have arrested development.
6. The fact that some of the thorn/branches are transitional, not quite thorns, not quite twig/branches lends credence to this theory.
I had never really noticed this phenomenon prior to today.
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I found a Poncirus branch with shoots that are transitional between thorns and normal shoots.
(https://i.postimg.cc/Q96f2Rz0/IMG-20200714-110505.jpg) (https://postimg.cc/Q96f2Rz0)
(https://i.postimg.cc/4KQL5KQC/IMG-20200714-110519.jpg) (https://postimg.cc/4KQL5KQC)
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I had a key lime I grew from seed years ago. It used to produce flowers at the tip of the thorn & fruit as well.