Enter the numeric sub part of the chromosomes text to search.
For example: enter "28" to search for "28 + 1B", or "14" to search for "14, 27, or 30"
This query finds cultivars by number of chromosomes. This may be helpful if you are hybridizing a new cultivar and you wish to see if the flower you are considering as a parent is a viable choice.
Daffodils and other flowering plants are fertile when the number of the chromosome sets can be divided by two and this gives a whole number. There are exceptions and mismatched chromosomes have occasionally produced offspring.
Theo Sanders of Germany has done an extensive study of pollen volume and chromosome content of daffodils. This study and others, including one about the possibilities of hybridizing, are available on Theo's site theo-sanders-daffodils.de.