The Tropical Fruit Forum

Thanks Ilya, I'll continue to observe the seedlings.

Tai-tri and 5* are mostly nucellar though, correct?

My impression had been that while there are a decent number of poncirus hybrids floating around, most of them are highly nucellar. These new ones from the USDA being nearly 100% zygotic struck me as exceptional. Curious about Bishop though, I've not heard of that one before aside from I think some of your posts kumin.

On related note, it'd be nice if there were, and there may well be, somewhere with data on these cold hardy hybrid varieties in a table. Would make trying to find the %nucellar, parentage, or estimated cold hardiness much easier to reference.

There are indeed cold hardiness tables, keeping them current to the latest introductions may be a challenge.
Bishop Citrandarin arose as a likely chance seedling among stock purchased from Stan McKenzie. The tree didn't fruit initially, but after a period it flower and fruit.
The initial discoverer provided me with fruit and grafting materials. It's seedlings show variability due to a degree of zygotic embryony.



Overripe Bishop Citrandarin fruits.

A few of the Conestoga selections have flowered and set fruit this Spring. Hopefully the fruitlets will persist until maturity. Some of the flowers were pollinated by Bishop pollen. Others were pollinated by Meyer lemon and 5* Citrumelo pollen



Conestoga 010 fruitlets.

Conestoga 006 fruitlet.

Conestoga 026 seedlings showing little to no variation. Clearly the majority are nucellar seedlings.


5 Star seedlings, there are likely some zygotic seedlings present.

 Variable Bishop Citrandarin seedlings.

There's a good chance this Poncirus Plus seedling is Tetraploid. Deep green, broad, short aspect and thick leaves are all indications of tetraploidy. Notched leaf margins are an additional indication.

Quote from: pagnr on April 26, 2023, 09:11:29 AM

The Bitter tasting fruit could have multiple functions. It could repel some creatures that eat seed, or don't effectively disperse the seed, but attract others that disperse the seed. A lot of wild fruit are not palatable to humans, some are toxic, but consumed by other mammals and birds.

The literature suggests citrus are consumed mostly by arboreal mammals (rodents, bats, primates) and frugivorous birds. There are some interesting overlaps between citrus's 'native' range and that of fruit bats.

I somewhat suspect citrus thorns are more to prevent megafauna (deer, elephants) from overly grazing upon the stems and leaves than they are to protect the fruit. Big thorns don't stop birds or small mammals. I'm curious whether citrus trees stop growing thorns at a certain height, like some trees do. (Once they get above how high their predators can graze)

\rodents and squirrels will of course eat nearly anything. They are basically tiny deer.

Poncirus thorns are most prominent on rapidly growing suckers and sprouts. They become much smaller higher in the fruiting canopy.

I planted the initial test plot at 20 seedlings per square foot. Survival rates were so low that the survivors were uprooted and replanted to recover space.. Advanced hardier populations will need to be planted at lower densities due to the increase in percentages of survivors. Moving forward, I expect higher percentages of survivors when crossing hardy x hardy parents.
Some of my crosses will be hardy to -5 F parent x 10 F parent. Perhaps 20 - 25% of these may be hardy.
A few of my selections approach Poncirus hardiness, however the proof remains in fruit taste.
The very hardiest trees had no dieback at prolonged 2°F temperatures. A month of such temperatures would likely be the death knell for them.

5* Citrumelo flowers just started to bloom. I've pollinated a number of these with Conestoga 010 pollen. Hopefully some of the seedlings will be hardier than 5*.

Several Conestoga selections blooming and several are fruiting for the first time. I'm discovering the first year flowers on a seedling tree are often predominantly staminate flowers. Last Spring 006 and 010 flowered, but failed to set fruit, as many of the flowers lacked styles. This being the second year, many of the flowers are perfect.



006 fruitlets

006 fruitlets



010 fruitlets

010 fruitlets

Many of these flowers are pollinated by either Myer lemon, or Bishop Citrandarin pollen.
I'm discovering that 010 and 006 are nearly identical in cold hardiness. 011 is very hardy, but likely equal to 006 and 010 rather than superior to them.

Bishop Citrandarin has survived the Winter in better condition than I expected. It certainly has the potential to survive 0°F.

 Bishop Citrandarin, possible progeny of 852 Citrandarin. This tree is grafted onto Poncirus and has only been field planted since last Summer. The tree was exposed to prolonged to 2°F temperatures accompanied by high winds. The tree exhibits obvious damage, but appears to be recovering. The original tree was planted and fruited by Hardy Vermont.