Polyploid plants contain more than two sets of chromosomes (diploid). A tetraploid, for example, has four complete sets of chromosomes in each of three apical layers, expressed as 4-4-4. A ploidy chimera, on the other hand, has different ploidy among the apical layers (for example, 4-2-2). The list which follows includes both those which are totally tetraploid and ploidy chimeras.
Many hosta cultivars have been suggested to be polyploids, but relatively few have actually been checked to verify it. One method to determine ploidy level is by flow cytometry. This research has been conducted primarily by Zonneveld and van Iren at Leiden University in The Netherlands.
Thick leaf substance is one indication of polyploidy, particularly when a sport or seedling is compared to the parent plant. However, leaf substance alone does determine ploidy. Hosta 'Grand Tiara' for example, is thin-substanced (.007" thick) but is fully tetraploid (4-4-4). On the other hand, hosta 'Blue Mouse Ears' was previously thought to be tetraploid because of its thick substance (.014"). Testing by flow cytometry, however, has recently revealed that 'Blue Mouse Ears' is merely diploid (2-2-2).
While the list below includes all hostas which are currently thought to be polyploids, those species and cultivars which have been confirmed to be so through laboratory testing are indicated with an asterisk (refer to the list of "Hostas Analyzed by Flow Cytometry"). The diploid or polyploid parent is shown in parentheses.
In an effort to keep this list accurate and up-to-date, please email all corrections and additions to