The further sexual exploits of Sorbus

One of the earliest posts on this blog referred to the penchant of the genus Sorbus to cross with other Rosaceaeous genera with surprising ease. I've been aware for a while of a couple cultivars derived from such crosses, such as Ivan Michurin's 'Ivan's Belle' (a cross with hawthorn), and 'Ivan's Beauty' (a hybrid with Aronia), but in general such hybrids have been more curiosities than serious attempts at fruit prodcution. That's why I was surprised to find a list of a number of such hybrids (it can be found here, but be warned: it's in Finnish). Here's the part I understood enough to find interesting:

'Eliit'--Sorbus aucuparia x Pyrus sp.
'Zoltaja'--Sorbus aucuparia x Pyrus sp.
'Titaan'--'Burka' x Malus sp. x Pyrus sp.
'Granatnaja'--Sorbus aucuparia x Crataegus sanguinea
'Likjornaja'--Sorbus aucuparia x Aronia melanocarpa
'Burka'--Sorbus aucuparia x [Sorbus aronia x Aronia arbutifolia]
'Dessertnaja'--'Likjornaja x Mespilus germanica
'Rubinovaja'--Sorbus aucuparia x Pyrus communis
'Krassavitsa'--Sorbus aucuparia x Pyrus communis
'Nurmes'--Sorbus aucuparia

(It's worth noting that the USDA GRIN system lists a slightly different parentage for two of these: 'Burka' (S. alpina x S. aucuparia), 'Likjornaja' (S. aucuparia x S. melanocarpa), and it lists the pedigree of'Krassavitsa' as "uncertain". (For those who are interested, the GRIN page for Sorbus is here).

(For those not up on their Latin names, Aronia is chokeberry (or just aronia), Mespilus is medlar, and Crataegus is hawthorn. And really, shame on you if you don't know that Malus is apple and Pyrus is pear...)

Anyway, I have no way of reading the Finnish portion of the PDF, so I don't know what they're saying about these, but this marks the first I've heard of several. Anybody who knows Finnish or knows these cultivars and wants to comment, please feel free to contribute.

Update: I've never had trouble with tables in HTML in the past (which was quite a while before I started this site), but for some reason I can never make them work right here. I always get a giant blank space before the table. I've gone with a slightly less elegant non-table version here, but it's really starting to annoy me. Any suggestions what I might be doing wrong?

Sorbus: Genus of Easy Virtue

I've been poking around for a while, looking things up here and there on the topic of intergeneric crosses. One thing you learn quickly when you start paying attention to plant breeding is that the rules you learned in high school biology about what will reproduce with what go straight out the window. Crosses between species, supposedly not possible, are pretty much the bread and butter of most breeding efforts (to be fair, the real textbook definition of species was 'reproductive isolation', which doesn't mean they can't reproduce, just that they probably won't for whatever reason...but I'm not betting your eighth grade science teacher knew or expressed the difference). That restriction sort of gets bumped up to the next level. In general, you can't make crosses between genera.

In general.

Species and genera are, of course, made by Man, not Nature, and Nature seems to have this thing about finding exceptions to the rules Man has tried to come up with. Intergeneric crosses do work, sometimes. In my yard right now, I have a little plant that looks quite a bit like a strawberry, called 'Lipstick'. Unlike strawberries, however, 'Lipstick' has bright pink flowers. Really quite attractive, though I haven't had fruit yet to attest to it's worth in that respect. It's a cross between Fragaria x ananassa, the cultivated strawberry, and Potentilla palustris, a related species for sure but not a member of the same genus.

Fragaria and Potentilla are both members of the Rosaceae, a family of plants which contains maybe a majority of the fruit crops out there (and yes, as you may have guessed, roses, too). A number of the genera out there are willing to play a little fast and loose with the rules. In addition to Potentilla, strawberries have been crossed with Duchesnea indica, the "false strawberry", and with raspberries. Luther Burbank, perhaps the greatest American fruit breeder (though not a scientist by any means) was perhaps the first to make this cross, which resulted in some rather odd plants.

Burbank was one of the great makers of wide crosses. He crossed apples with pears, apples with rose, pears with quinces, strawberries with dewberries, etc. The Russians were also big on this sort of thing. Partly because their climate is almost universally horrible (I said "almost"...yes I realize parts of it are just lovely), Eastern Bloc breeders have always seemed a little more anxious than most to make weird crosses. One genus that seemed particularly amenable to their fiddling was Sorbus, or mountain ash.

Probably one of the better known intergeneric crosses in the family is 'Shipova', a cross of mountain ash and pear from Yugoslavia. It's available commercially here and there, and is actually pretty good from what I've heard. Russian breeder Ivan Michurin created 'Ivan's Belle', a hybrid between mountain ash and hawthorn, also available here. Hybrids of Sorbus exist with Cotoneaster, Aronia, Mespilus (medlar), and Amelanchier (serviceberry), and it's tempting to wonder how many other obscure ones might work if some one tried them enough. Some of the hybrids, like Sorbaronia have been found occurring naturally!

Ultimately, though, the successes of intergeneric crossing have been few and far between, though its promise to any breeder is obvious: opening up an entire new pool of germplasm. If only it was that easy.