Hello. I am trying to self a Primulinum cross and am wondering if there is a list of known sterile Paph hybrids. Anybody know? J

Not sure if there is a list or not but anytime a species is crossed to another subspecies or genera, they are usually sterile.

There isn't a list, it is just a matter of knowing your plants. Any plant that is a 3N is not a likely breeder when bred with 2N species or hybrids. Sometime, 3N plants will produce fertile hybrids with a 4N parent. Some plants are simply not fertile, especially if chromosome counts are incompatible. The easiest method is to breed 2N with 2N.

Informative and interesting subject!

what does the 4n and other N's mean???

Try these links -

http://en.wikipedia.org/wiki/Ploidy
http://www.bedfordorchids.com/ploidy.htm

Within genus Paphiopedilum I don't think you can make any general statements about any particular hybrid always being sterile. Some individual clones may prove to be essentially sterile if many and various crosses have been attempted and have not been successful, and fertility may be very low for most triploids and when chromosome counts of parent plants are mismatched, but the large number of potential seeds in a single pod gives at least a small statistical possibility of success.


In somes cases it can make a big difference whether you use a plant as the pod or pollen parent, and what species or hybrid you pair it with. In many cases self-pollination is less successful than outcrossing. And it also depends on the ploidy of the parents of the hybrid, and every hybrid can be made many times with different parents. In theory, any hybrid should have reasonable fertility if both parents are tetraploids.

what does the 4n and other N's mean???

Most species plants have one matching paired set of chromosomes. These plants are called diploid (or 2N). A few plants may have 2 full paired sets of chromosomes, and these plants are called tetraploid (4N). Eggs and pollen produced by a plant typically split up the paired chromosomoe sets of the parent, so a 2N plant produces 1N eggs and pollen and a 4N plant produces 2N eggs and pollen. So if you cross a 2N plant with a 4N plant you get 3N (triplod) seedlings.

In rarer cases you may find 1N (haploid), 5N (pentaploid) or 6N (hexaploid) plants, but I'm not sure these have been shown in orchids. In some cases you can accidentally get an extra chromosome (or several) and these unmatched sets are called aneuploid. In animals these unmatched sets of chromosomes usually are not viable or may caused abnormalities (like Down syndrome) but in plants they are often healthy and normal in appearance.


Different species can have different characteristic numbers of paired chromosomes making up a set (different chromosome counts). If you cross a plant with 18 pairs of chromosomes with a plant that has 23 pairs of chromosomes the seedlings may be perfectly healthy but it is difficult to split the mismatched pairs to make viable eggs and pollen, so fertility is reduced. Triplod or aneuploid plants also produce eggs and pollen with unbalanced sets of chromosomes, and show reduced fertility. But in all of these cases of mismatched chromosomes a few eggs and pollen may happen to end up with viable combinations, so sterility is rarely complete.