How to differentiate between 2N, 3N and 4N?

[Nelson Wong]

How do we know or differentiate if an orchid is a 2n, 3n, or 4n? are there any characteristics? or do we have to actually do a test?

 

[NYEric]

Visually, increased ploidy plants exhibits thicker leaves, and the foliage is almost imbricated. They are usually slower growing but better shaped blooms.

 

[Nelson Wong]

do you have an example of imbricated foliage? some visual could help

 

[NYEric]

Not me but see if there are photos of 4N plants on this site or on Orchids Limited's site.

 

[CharlesD]

You would have to do some research but for Cattleyas at least there are flower characteristics (beyond just being bigger) that indicate polyploidy. Look at Roy Tokunaga’s writing in the AOS magazine or look up papers by haruyuki kamemoto also don wimber. Without counting chromosomes the breeding behavior of a plant will help you differentiate. Eg 3N being mostly infertile. Sometimes diploids will breed readily but the offspring may not be fertile depending on the other parent. 4N plants will dominate the other parent if bred to a 2N. There’s a lot info to dig into about ploidy

 

[big923cattleya]

4N Cattleya seedlings or plants, with which I am the most familiar, are indeed slower growers, I agree that they often show thicker leaves, rounder leaves and they typically produce flowers with heavier substance. The color of the flowers is often deeper, richer. As seedlings, they often show several new leads at once rather then just one or two.

They could be larger but that is often controlled a bit by culture. If you grow a 4N Cattleya poorly, something tells me that the flowers are not automatically larger.
I agree, unless you run a dna test, how could you possibly know for sure. But like I said, you have to grow them well.

 

[littlefrog]

Indicate only... The only way to know for sure is to count the chromosomes. Problem is if you do a visual analysis you have to compare to a known standard. To get a known standard you need to count. Anything short of that is guessing. Perhaps educated guessing, but still guessing. Breeding behavior is a pretty good indicator, but that takes years to figure out... Longer than I have.

With phrags it is kind of a shorthand to guess that something is polyploid based on the presence of extra tissues or 'teeth' on the flowers.

 

[Happypaphy7]

Exactly. Those can be all misleading and should not be labeled as 4N unless actual chromosome counts have been conducted on the said plants.

 

[gonewild]

The old fashioned way was to try pollinating the flowers. If it refuses to set a pod it's likely 3n. And if it refuses to set seeds it really doesn't matter what the ploidy is.

 

[sergeharvey]

Read: https://www.mdpi.com/2223-7747/11/4/469

 

[mrhappyrotter]

Indicate only... The only way to know for sure is to count the chromosomes.

This is essentially my response, too!

Having said that, the sarcastic response is: Read the tag (if you bought from a reputable vendor). These will usually indicate if the plant is anything other than diploid. And the best tags will list parental cultivars. If so, you can sometimes further research the ploidy of those individual cultivars if you're savvy enough and know where to look.

The practical answer is: Sometimes you can make an educated guess based on appearance, sometimes based on the plant's provenance, and for breeders, they can sometimes tell from seeing what other individuals they are sexually compatible with (schwing).

Also, polyploid orchids (3N or more) are generally regarded as more valuable than diploid orchids, so this is a case where there's economic incentive to "advertise" if the plant is 3N, 4N, or higher.

 

[littlefrog]

...
Also, polyploid orchids (3N or more) are generally regarded as more valuable than diploid orchids, so this is a case where there's economic incentive to "advertise" if the plant is 3N, 4N, or higher.

For showing and overall vigor, 3N seems to be the sweet spot. I'd say for the vast majority of collections that works. If you want to breed, then tetraploid is best Phrags at least.

I'm not sure about paphs... While there are certainly polyploid hybrids (most of the bulldogs, I think), it doesn't seem to do much for the species. Long way back I bought a bunch of different colchicine treated flasks or seedlings. It didn't work out. Most of it grew very slowly and I don't think anything bloomed. That was back when I was young and optimistic - maybe someone else had some luck. I don't have the space to bloom out dozens of each, perhaps it works if you have a bench full.