Prague Citsuma

Prague Citsuma or   +Citroponcirus 'Prague'

Prague Citsuma may be the best citrus available that combines cold hardiness and taste.  Surviving 3°F (-16°C) 1, and 1°F (-17°C) 2 without damage, making it hardy in Zone 7a, and perhaps Zone 6b

Ripe fruit are sweet without the bitterness of Poncirus.4 Leaves are small and widely spaced.  The leaves vary between trifoliate, bifoliate and unifoliate.  Branches are thin and slightly pendulous.

The origin of Prague maybe unknown.   B. Voss received it from the from greenhouses ITSZ from Prague. ITSZ is the abbreviated name of the Institute of Tropical and Subtropical Agriculture. This is a Faculty of Agriculture University. It is suggested that it came from Russia.  It is possible it could be the Chinese chimera Hormish, but small fruit of Prague are not  pubescent.

Chimera
While in a hybrid all the cells are genetically identically the same,  'a chimera is a plant composed of two or more genotypes in the layers that make up the shoot tip' 3  For Prague, based on taste and appearance, the fruit cells are Satsuma, and the stem tissue and part of the leaves are from Poncirus, possibly Dragon.

 Woody plants have three dividing cell layers at the growing tip.  They are named L1, L2, and L3.  L1 is the source of the exterior of the stem and the top of the leaf.   It makes the epidermis, stomata, and sacs in fruit. 4  In the diagram, the green color are the cells from Poncirus, L3

It is probably a chimera 2  for the following reasons
1) Quality of the fruit
2) Appearance of the leaves in the winter indicating a mixture of genotype.
The L1 epidermis
L1 sub epidermal layer
L3 corpus, inner layer, center of leaf, also vascular bundle.  L3 is poncirus

Schmidt (1924) presented the “tunica-corpus” concept to describe the stratified appearance of the cell layers in the shoot apical meristems of flowering plants. Most dicots have three distinct apical cell layers (L₁, L₂, and L₃) that remain independent from each other...In citrus fruit, both the juice sac and pericarp epidermis originate from L₁; L₂ ordinarily produces seeds, segment walls, the hypoderm, and the mesocarp of pericarp; while L₃ develops into the vascular bundle

According to the “tunica-corpus” theory, a plant chimera is a mosaic in which genetically different cells exist in the shoot apical meristem that gives rise to cells that develop into organs of the plant.5

Pictures taken in January 2020 showing the yellow in the center of the leaves from Poncirus cells. 
 
 

Virginia Fruit Grower Video

 

Nansho Daidai, Taiwanica

Nancho Daidai sour orange

Citrus taiwanica

 'is a very hardy tree and an upright, vigorous grower with long, narrow leaves and huge spines. The fruit is large, oblate-spherical, and bright yellow. Over the years, Nansho Daidai has proven to be one of the hardiest evergreen citrus. A citrus pioneer in Montezuma, Georgia had a large Nansho Daidai that endured 0°F in 1985 without any noticeable leaf drop, and no loss of crop the next year. How much below zero this citrus can take is unknown, but it’s certainly a hardy variety. Fruit quality is only mediocre, though the fruit can be used as a lemon substitute and for making very good -ade type drinks. Hardy to 5°F easily. Flavor: Sour lemon, some off-flavors, fair quality.' (1)

Related to sour orange (2)(3)

 Depending on location and weather prior to cold events, hardy to about 5 degrees(4)

 30% of seed is zygotic

Eyeckr provided these fruit. Fruit is juicy, flavor is very similar to a bitter lemon, however when diluted and sugar added tastes like lemonade. Fruit is seedy, having 37 large seed. Large fruit, 116 gms, small fruit, 96 gms. Brix 11.9

Swamp Lemon

From cache of Citrus forum:
http://webcache.googleusercontent.com/search?q=cache:izGDY9FcFX0J:citrus.forumup.org/about3639-.html%26highlight%3D+&cd=1&hl=en&ct=clnk&gl=us

Posted: Thu Oct 09, 2008 12:42 am    Post subject: Swamp Lemon
Not sure if this should be listed here or roostock. Anyway... Terry sent me some fruit with the below story attached. The fruit is the size of large Trifoliata fruit. Same look & texture. The thing is these fruit don't have the stink of standard Trifoliata. Too late to take photos, I will get some tomorrow, clean the seed and let you know what I find. Quote: Swamp Lemon Story   I finally got up with the guy who has the Swamp Lemon.  What a neat old guy.  He reminded me of my grandfather. Here's what he told me so far.     That he was 14 when he was hunting on the Livingston Creek in Delco, NC.   He saw the swamp lemon and asked he's older hunting companion about it.  His friend said that the Swamp Lemons had grown wild there on Livingston creek for as long as he could remember.  This guy Charley said that as that was 60 years ago and adding his friend’s age would make it about 125 years that these lemons were growing wild there.       I think the 60 years is reliable. I'm not as sure of his old friends extra 45years.  So, this Swamp Lemon has been growing there for 60 to 125 years.     He said that most people who live in that areas have these lemon trees growing in their yard by digging them up from this creek.  But as far as I know the Swamp Lemon trees are only growing wild along the west side of Rte. 74 where it crosses the Livingston Creek.     So I'm thinking that some one brought a fruit there from FL about 60 to 125 ears ago. The trifoliate may have been cross-pollinated from an orange.  But the fruit doesn’t look much different than trifoliate. I am surprised that in 60 to 125 years that all of the Cape Fear river isn't covered with Swamp Lemons because Livingston Creek flows into the Cape Fear River.  The Lemon site is only about 30 miles from Wilmington. Maybe the brackish water helped. After a lot of effort I obtained some fruit and seedlings and some cuttings. Now here’s the thing. The fruits flesh has no trifoliate taste or smell. None at all. The peeling has a slight off smell and a gummy nature to it. It doesn’t taste good or bad it’s kind of bland. The taste is closer to an orange than a lemon but definitely citrus. I don’t know if a regular Trifoliate has a lemon or orange taste. All I remember of the one I tried to taste was the terrible smell that was nauseating. But, unlike the usual trifoliate you can eat it. I was told that some have made lemonade with it. So, I tried it. On a scale of 1 to 10 I’d give it a 5. If you live in a zone 9 or 10 it wouldn’t impress you. If you live in a zone 6 or 7 and wanted to say you drank a Trifoliate lemonade it wasn’t bad. My question is,” If a Swamp Lemon used this to re-make some of the early trifoliate crosses do you think I would be ahead of the game taste wise? This doesn’t seem to be a soil generated taste difference. The Swamp Lemon that I got is at the least third generation from the original tree and is 10 to 15 miles from the original tree. The flesh seems more yellow than Poncirus and the juice has an agreeable sour taste. There were Poncirus oils in the skin though, and the fruit size (external appearance) was more similar to Poncirus than citrange.

Citrus Boards and Blogs

If you know of Hardy Citrus Boards or Blogs, send a link, thanks.

Czech:  http://www.citrusy.estranky.cz/

Czech: http://www.subtropicke-rostliny.cz/forum/viewforum.php?f=22

English and Finnish:  http://citruspages.free.fr/

English (UK):  www.homecitrusgrowers.co.uk

English (US and International): archive of citrus forumup.    It has a lot of information that cannot be found elsewhere.  Thanks to Sylvain for all his work.  

English (US): The new English site for Hardy Citrus
             http://tropicalfruitforum.com/index.php?board=14.0

English (US):  http://www.permies.com/t/20777/trees/Cold-hardy-citrus-trees

French:  http://www.agrumes-passion.com/

French: http://www.forum-agrumes.com/viewforum.php?f=13&sid=d7fa104a25a06c688b6dade0dfd6e403

French: https://myfruitgarden.wordpress.com/

German:  http://www.exotenundpalmen.de/f5-Bananen-Citrus-Palmfarne-Baumfarne-Gehoelze-Bluehendes-mehr.html

German:  http://zitrusgarten.net/

Hungarian:  https://plus.google.com/107150318774510322151/posts

Hungarian:  http://citrusfa.blogspot.hu/

Italian:  http://www.fruttama.it/forum/viewforum.php?f=10&sid=8f996a5466d05c321949830667daea24

Polish:  http://cytrusy-mrozoodporne.blogspot.com

Polish:  Citrus in general http://www.cytrusy24.pl/  Specific hardy section http://www.cytrusy24.pl/forum-cytrusowe/cytrusy-mrozoodporne/

Russian:  http://forum.homecitrus.ru/topic/18215-tcitrusovye-v-otkrytom-grunte-v-polusubtropik/

Russian (Ukraine):   http://citrusforum.org.ua/

Russian (Ukraine):   http://myflora.org.ua/forum/viewforum.php?f=4

Spanish:  http://foro.infojardin.com/forums/citricos.85/

Not a board but a small book.  Hardy Citrus of the Southeast by Tom McClendon. pdf file   Dozens of hardy citrus varieties described

Strange plants

 Miniature plant almost 3 years old.

Diploid Poncirus top leaf, Tetraploid Poncirus bottom leaf.

Tetraploid Swingle

Natural high ploidy seedling

Leaf thick and leathery.

F2 from probable Hirado Buntan x Poncirus

Ventura Lemandarin

Lemandarin is a cross between Citrus tiawanica x (Keraji or Satsuma) It looks like a satsuma.  Resistant to soil diseases that have killed my other seedlings.  Vigorous. 

From the breeder:  As far as hardiness my seedling Lemandarin never flinched in the cold weather until this past brutal weather. It survived at least to I think 11°F, -12°C degrees and a few 13°F and 14°F, -11 and -10°C events in the past. This winter it reached its max tolerable temp where it died at 5.5°F, -15°C on its own roots. Less than a foot away I had a back up graft of it on flying dragon about 4 feet up that defoliated with branch die back but is growing back very well. I can attest to that at least when high grafted it can at least withstand about 6°F, -14°C.

May come true from seed.

Mild lemon flavor.

Update: January 21, 2020
Eyeckr provided another fruit.  Smell is good.  Taste is excellent, like an orange with some lemon.   Brix 13.3  Peels more easily than a mandarin.  2 3/4 inch, 7 cm diameter.  3.8 oz, 108 gms. 28 seeds.  Skin bitter. 

Where to buy

USA:

  New:  Simply Citrus Nursery 
     In Columbia SC


All kinds of hardy citrus in SC, Stan is a great guy:  Mckenzie Farms

Huge assortment of plants grown from seed in SC: Woodlanders

Hardy Citrumelo:   Chilly Palms

Citrus in Virginia: Pungo Palms

Another Citrumelo: Logees

Eight kinds of hardy citrus in Ca: Rolling River Nursery

A few from Tennessee:  Ponds n Plants

Three mandarin in NJ:  Triple Oaks

Flying Dragon in NC: Useful Plants

Sudac and others:  One Green World

Satsumas and more: 
Hardy citrus restricted to Fl:  Just Fruits and Exotics

Yuzu and mandarin and more in Ca:  Four Winds Growers


Europe:

Czech:  Exoticke Erostliny

             Good source of information

            Adavo

 Germany:  Flora Toskana

France:  Jardinerie Riera
              La Pépinière du Bosc
              Le Monde de Agrumes Baches
           
Italy: Oscar Tintori

         AgrumiLenzi

Netherlands: Citrus BaLi

Spain:  Citrus and Life

 Switzerland:  Eisenhut