The Tropical Fruit Forum

Sometimes patience is needed. I once bought Citrangeremo, grafted on Swingle Citrumelo, from Zdenek's old shop. It is now well over ten years ago. The first bloom and the first fruits were this year.
The plant was a vigorious grower from the beginning. It first stood in a sunny greenhouse. But that was probably also the reason, why it was serverly frostbidden some few degrees below freezing. But it soon recovered.

Out of some bureaucracy issues, I had to move my greenhouse or I shall better say rebuild it at a place under a huge poplar tree were it had shadow from about 14:30 o'clock to about 17:30 o'clock. Not ideal indeed but also not so bad as expected. It was save from too hot temperatures and most citrus trees (Citrumelos, Poncirus, Keraji etc.) grew well there.
The Citrangeremo in special had originally an acceptable amount of sun but was then more and more overgrown by Swingle5Star seedlings on the right hand and African Shadock x Poncirus on the left hand. It found its way into the light nonetheless but had certainly not enough sun.
Now this is its place and condition:








As you see the greater part of the plant is overgrown by the trees from the right and left.

Here is a view into the greenhouse from the front:



You see it is pretty full. But what you see here is already the greenhouse update from this year. The original greenhouse was only half as high so that the bigger plants were pressed together under the roof. You still see it when you look at the citrumelo with the yellow fruits (Swingle 5 Star mutation by the way). Rebuilding the greenhouse was a lot of work and I did not finish the roof until mid of November this year.
I say that in order to help you assessing what I am going to write about the fruit quality of Citrangeremo. I will speak about fruits from a plant that did not grow under the best conditions, that stood in a greenhouse but was from July on exposed to our rainy and cool summer, not protected by a roof. The leaves are also a bit too yellow and growth was not the best this year (reason unclear).

Patience... Having said all that you have also needed patience. My first bloom was this year. And this year, I also got the first fruits (after well over ten years).

The fruits. First some pictures:









You see the fruits are very small, 1,5 cm at most. And they may be not totally ripe. There is still a whiff of green on some fruits.
I come to the interior qualities.
The peel is extremly thin, 1mm at most, perhaps even less. It has almost no white part, yet fruits can be easily peeled. The peel is full of oil glands that are relatively big when compared to the thin peel. The peel has no Poncirus off-flavours but tastes bitter. It reminds me a bit of Calamondin peel but is more bitter.
The pulp consists of more or less round orange juice sacks. They are quite firm but juicy. They have no tendency to plopp out of the fruit as do the round juicy sacks of Fingerlimes. They stay where they are. They even stay at their place, when you peel a fruits that has already been cut into to halves.
The pulp is mildly sour with an orange taste. It tastes quite similar to Calamondin but goes more into the direction of orange taste than to mandarine taste although both flavours are present. The fruits are pretty aromatic but I have the impression that Calamondin has more taste. The pulp is NOT bitter and has no Poncirus aromata.
Segment walls are no hindrance for enjoying the fruits but are well developed.
Generative aspects: Citrangeremo had only well developed flowers with pistil and stamen but it did not produce pollen. The stamen remained closed and it also did not help to dry up the stamen and grind them. There did not appear any yellow or dusty substance. I pollinated every flower of my Citrangeremo with fresh pollen of Staraji and partly also with fresh Poncirus pollen. But I have so far not found a single seed, not even an underdevelped one. I have not checked all fruits yet but have  open enough of them to conclude that Citrangeremo is likely to be a very difficult elder for breeding.

My overall evaluation: Is Citrangeremo is great variety for eating or breeding?
Hmm, the pulp is tasty but the bitter peel is really a detriment.  Ok, it can easily be peeled. But who wants to peel such small fruits? I am willing to believe that Citrangeremo bears better fruits under better growing conditions. Maybe much better fruits. But will not the peel remain bitter?
Another disappointment for me is that the fruits are not really early ripening. We have now Dec. the 8th and they are not fully ripe. Ok, my climate is a challange and Citrangeremo was not amoung the early blooming varieties. It started blooming a bit later than Staraji but overlapped with its blooming period. Poncirus is much earlier, Citrumelos also earlier. Late bloom can be an advantage where late frost is to be feared. But look the small fruits of citrangeremo and now Swingle 5 Star (Mutation) with its much bigger fruits. The latter ones are now also almost ripe. See here:


The Citrumelo fruits have suffered from the same weather but have a taste that is quite ok for Citrumelos. Citrumelos are so much more productive.
Ok, Citrangeremo is not really late ripening but seems to be not early either. Who wants to breed early varieties shall not be deterred knowing that Citrangeremo is half E. glauca and E. glauca is early. A breeder should not look at the phaenotype but at the genotype. Yet, how can you breed with something that does not produce pollen and seeds?

My overall judgement is: Citrangeremo is an interesting curiosity and it is not bad. But it is not as great as it is rare. Buy something else for fruits and breeding.

I am looking forward to the next years and to the experience of other. If you ever had Citrangeremo fruits, please post your comments! When I get fruits again next year I will inform you.

I would like to know more about the chemical nature of sticky substances like poncirin etc. Perhaps here is somebody who has scientific background (genetics, chemistry, or just read something) that can help me to get a bit deaper understanding.

I got the question because of some observations:

--> Poncirus contains a sticky substance called poncirin. It is often described as bitter and certainly as disgusting. Yet not all types of poncirus get bitter fruits (bitter in the narrow sence of the word: bitter like vermouth) while all - so far as I know - contain a sticky substance.

--> Some poncirus hybrids that I have tasted (Morton, Swingle 5 Star, African Shadock x Poncirus, a certain Citrumelo probably Sacaton) contain flavour components associated with the sticky substance of poncirus, some however very deluded (Morton). Yet pure poncirus juice often looses its disgusting flavour when it is allowed to stand one night in an open glas so that the sticky substance sinks to the ground. Even the odour of the juice is then pretty good. The same is true for Morton juice which hardly contains any sticky substance. If even the odor of the juice becomes good is then the bad taste perhaps something more volatile than the sticky something?

--> A fruit of Dunstan citrumelo that I could taste definitely contained a sticky substance but I found its taste not disguisting at all. The fruits were a bit sticky but tasted very good. So is the sticky substance really the reason for the bad poncirus taste or is the bad taste something independant of the sticky something? Does the sticky substance only accumulate the bad taste that would be there even if there was not resin in the fruits? Or is the sticky substance in Dunstan Citrumelo something chemically different from that in poncirus fruits?

--> C. ichangensis also contains a sticky substance around its seeds. But it tastes different from that in poncirus and is, at least to my taste, much more tolerable than that of poncirus. Is it chemically different?

--> C. australasiaca has some "glue" around its seeds not much but something. It tastes, however, ok.

--> The peel of pumelos (C. maxima) has a taste remiscent of poncirus fruits. Is it the same substance as in poncirus fruits?


To sume up my questions:
--> How many different sticky substances exist in citrus (including poncirus and eremocitrus)?
--> To what degree shall we distinguish between the sticky substance and disgusting taste?

Hello,

I was wondering what happens when you double the chromosome number of a citrange. Will it be more tasty or more hardy? Has anybody an idea or even practical experience? I am a bit inspired by kumins seedlings but do not no if the tetraploid state of one of his hybrids matters.


I have by the way drunken my first pot of Morton Lemonade. Outstandingly good! Very tasty! The trick was to let the juice stand open for one night so that the (weak) Poncirus off-flavours faded away. (That also works well with pure poncirus juice if you don't use the bottom fraktion of the juice with the poncirin.)

I am curious now what will happen if I make for example the Morton citrange tetraploid. Will it be even better or more hardy?

Hello,

I had to prune my Changsha Citrandarin - tragically enough. There was critical bark die back due to a wound infected by mould during our wet winter. So I had to cut off one of its two biggest branches, about 80 cm long and very well branched. Now I have this otherwise very strong branch and can send it whole or in parts to those who would like to have budwood or cuttings.

I have the plant from www.pflanzen-des-Suedens.de (Mr. Meeder, Germany). It is still listed there (https://www.pflanzen-des-suedens.de/Citruspflanzen/In-Vorbereitung/; No. 9). I have not yet gotten fruits. So all that I can say is that it is a strong plant on Poncirus rootstock that has thick thorny twigs and thick evergreen leaves.

In case that more than one person is interested I would divide the branch. I live in Germany. So I can ship to countries in the EU, probably to Brittany, Switzerland and all countries that have no importation bann for Citrus plants.

Yours,Till

Hello,

I just want to share with you a picture of a Calamondin X Poncirus hybrid that I created. It is slow growing but look healthy. This plant, and a very tiny sibling, were the only seedlings of that year that grew under hot summer conditions in full sun and in mostly moist loamy soil. Root development was good. No signs of root rot at all. They did not grow well in half shadow and under cool conditions. Yet, they had no root problems under these conditions, either. The last growth, as you see, was not finished before winter. That is the reason for the yellow leaves.
Here the picture of the bigger seedling:


I had a few more Calamondin x Poncirus hybrids. But not all survived. Some germinated readily but grew only to the point when all nutritients from the seed were consumed. No obvious root problems. But finally they died. I suppose a genetic reason.
I am though very encouraged to try this type of cross again. Although Calamondin is highly polyembryonic I received some monoembryonic seeds and hybrid embryos from polyembryonic seeds. My pollination technics was quite superficial. I did not castrate the flowers. I did not even care that the flowers were newly opend and fresh. Bees were present all the time. But still I got a handfull hybrids from perhaps 30 fruits.

I also tried to pollinate Limquat with Poncirus. That also worked well. I had about three hybrids. But they died. The roots were too sensitive. But under different conditions I might have saved them.

Why did a do these crosses? Well, my idea was to produce something like a Citrangequat with higher Poncirus influence. I want to see to what degree Kumquat genes can suppress the bad taste of Poncirus. And I hope that my hybrids inherit from both Poncirus and Kumquat the feature that they bloom before shooting. If they do that would mean one more month for the fruits to ripe, that is one more month for fruit development before winter comes. I read it is hardly possible to cross Kumquat with Poncirus directly. So I tried Kumquat hybrids.