Are these thousands of cultivars all cloned and grafted? I thought the vast majority were all hybrids descended from a handful of parent plants, like African Violets. No?
An Acer cultivar is a proper clone of the original plant, either grafted or a rooted cutting (or layered, tissue cultured, etc.) Some of the original parent plants are certainly hybrids, others mutations. A. palmatum has a very unstable genome. I don't know anything about African Violets, are seedlings allowed to be sold as named cultivars? Or are they apomictic or something? There are a few palmatum cultivars that are completely diluted and practically meaningless, e.g. atropurpureum (as opposed to var. atropurpureum). And there are some seedling selections that are supposed to come true, e.g. A. tartaricum ssp ginalla 'Flame'. How similar they are to each other is anyone's guess... There are even interspecies hybrids that are then grafted along, e.g. 'Yasmin' -E
emery, thank you. if a cultivar is a proper clone of the original, why does it have to be grafted? for african violets, most of the varieties? cultivars? not sure the right scientific name are bred down from one or more of the species plants and known hybrids and then cloned for the larger market or mutations that are then cloned. Very few cultivars come true from seed. You can't name a cultivar or hybrid without going through one of the AF or gesneriad authorities, as far as I know.
All Acer palmatum cultivars belong to just the one species, no hybridity involved. Any truly hybrid Japanese maples that might happen to be grown will not be listed correctly as A. palmatum this or that because listing a cultivar with the name of a (non-hybrid) species preceding it - when done correctly - indicates it is a pure form of that species.
Ron has elucidated where I wasn't very clear. The example of Yasmin is interspecies between shirasawanum and palmatum (it is believed). There are many of these both known and as naturally occuring hybrids. Personally I think it likely that some of these are pollinators, producing palmatum selections that are then grafted on and labeled (incorrectly as Ron points out) as palmatum. I think this must happen to us all. When I grow a seed bed of say Villa Taranto, there's a wide variation between seedlings. As I grow on the more interesting ones, I can't know whether they're interesting because the japonicums or shirasawanums nearby hybridized, or just because there was an cool mutation. I'll label the plant "AP ne Villa Taranto" (with the other pertinent info) because that's the best information I have. The answer to your question about grafting is that that's just the most economical way to vegetally propagate at industrial scale. However, there are other ways, and sometimes cultivars are very difficult to graft. So a rooted cutting (which some authors consider unreliable, but seems to be coming into vogue for certain cultivars), air layering are also used (ex. for the beautiful A. pictum 'Usugumo'.) What I'd like to see is reliable grafting understock produced clonally by tissue culture, so that we could avoid so much loss from inferior stock that freezes, gets sick, etc. Well, I can dream can't I! :) -E
That is a wonderful dream, emery, and one I share where out rootstocks are clean and healthy so the whole plant (rootstock & grafted cultivar) does not die or develop some compromising disease. I am so tired of losing lovely A palm cultivars despite lavishing them with loving attention all to naught.
...about acer pictum Usugumo ,a see in Villa Taranto that is propagate with very good % of successful by air layering :) about palmatum cultivar born from seeds and after many years of observation ,if the character remain stable ,cloned by graft on palmatum because is very hard maybe impossible another equal plant from seed natural hibrydize is possible in cultivation one is griseum x pseudoplatanus; in forest one is acer x ramosum (campestre x pseudoplatanus)
