Hello!

The botanical garden of my town, Mainz (Germany), has a citrus tachibana shrub. The fruits are like small mandarines but are so sour that they are almost inedible. But anyway, I got interested in the plant. I have found in the internet that the plant is reasonable cold hardy. But does somebody of you know how hardy it is? I am of course also interested in other information about or experiences with citrus tachibana.

Greetings from Mainz where the sping is slowly approaching.

Till

Hello Till.
Not much of help, anyway:

"C. tachibana exhibits significant cold hardiness...
and may be usefull in developing cold hardy citrust ypes"
http://hortsci.ashspublications.org/content/27/1/43.full.pdf

Distribution
Asia
Japan - Honshu [s.w.], Kyushu, Ryukyu Islands, Shikoku; Taiwan

"The widespread occurrence of the tachibana, from southern Taiwan to the southwestern province of the main island of Japan, makes it very probable that it is in fact a wild species that has persisted since prehistoric times."
at http://idtools.org/id/citrus/citrusid

List of variations at IPNI http://www.ipni.org

Interesting, the article mentions the Ryukyu Islands. I lived on the Ryukyu Islands (Okinawa) for two years, and never seen a single citrus tree of any type anywhere. - Millet

Thank you very much for all your replies! I know much more now through your comments.
I myself have found in the internet that Citrus tachibana drops its leaves in the winter. I doubt that, however. But it might be that it has a tendency to do so in an hostile climate like some varieties of Citrus ichangiensis are also said to do. The plant in the botanical garden Mainz has dropped a lot of leaves but I do not know how to interpret that for it is in a very poor state anyway. One thing only is clear: That plant in Mainz stands in a glas house. So it has not seen frost this winter.
I think I make some scions this spring and see how it behaves when it is well fed.

Could it be that Citrus tachibana is a synonym for Citrus depressa from which Shekwasha is a cultivar? Compare the following pages:

http://en.wikipedia.org/wiki/Shekwasha
http://users.kymp.net/citruspages/mandarinhybrids.html#depressa
http://idtools.org/id/citrus/citrusid/factsheet.php?name=Shekwasha

The first two pages mention Shekwasha as Citrus depressa and do not mention Citrus tachibana. But the last page gives C. tachibana as a synonym. As I see it, however, this Shekwasha (= Citrus depressa) is a cross with C. tachibana as one elder, according to the last page. Is that right?

Fast search of "Citrus directory ver. 2.0",
http://corsica.corse.inra.fr/sra/synonym.pdf
gives no connection between C. tachibana and C. depressa (or Shekwasha).

Dear Till, here is some additional information -
http://davesgarden.com/guides/pf/go/121697/
I have seedlings of C.depressa from Japanese seeds and want to try it outdoor with protection in the next year. In the autumn young seedlings has no damage after -7C.
Best regards from Russia.
Anton.

That you two saw no citrus tree in the Ryukyu Islands can mean two things: Either the description of the native region from the internet is wrong, or the tree is hardier than any other citrus tree there but is extremly rare on the islands. It would be good we could again check the islands. But since you are both citrus freaks I tend to believe that the plant has disappeared from the islands or was never there. Both amounts to roughtly the same: Its not hardy enough.

Because the Japanese people use English words in a kind of idiosyncratic way?

No, it's because they pick them green and use them like(as) lemon.

Ah, that makes sense!

Ok, lets gather the facts: Citrus tachibana ist not the same as Citrus depressa. It is a native variety und hardy to -12°C (-10°F). Its fruits are small, extremly sour but aromatic. They can easily be pealed. C. tachibana becomes a big tree. And it is reported to drop its leaves in the winter - at least sometimes.
By the way: Its flowers have a very nice and strong smell.

What we should still know is whether it is polyembryonic or not and when its fruits are ripe.

At any rate, I see it might be interesting for crossing. And I want to have it .

Till, one small correction...that's 10°F, not -10°F