Thanks, Richard. I replied a bit on an earlier thread devoted just to Kokuso. It’s amazing how much of the info bandied about for years is completely wrong. I thought, and was told, it was from Korea, but it was bred in Japan well over 100 yrs ago for leaf production used as silk worm fodder. Just reiterating here for clarity.
I’ve generally seen Kokuso 20 listed as Morus latifolia, but my impression is that Morus taxonomy is kind of a mess, particularly the ‘other’ Asian species macroura, bombycis, latoflia, etc. all of which are variously classed as alba depending who you ask. Kind of reminds me of readjng about taxonomy for some of the other notoriously tricky genera, like Salix, Amelanchier, and (especially) Crataegus. Probably this sort of thing is changing somewhat with latest bio-tech methods, but I recall reading that botanists classify North American Crataegus into as few as ~10 and as many as ~200 depending. I guess you call that dichotomy the ‘big tent’ vs ‘little tent’ or some such, but basically it’s predicated on assumptions about what degree of difference is sufficient to constitute a species. With everything being observational and morphologically based, the genera that hybridize freely would seem to really stretch the species concept, if not turn it on its head!
In any case, your Morus phylogeny project sounds like a rad one. Thanks for tackling it and sharing about it with us all. I look forward to the seeing the results someday.
Funny about the ‘dwarf’ leading the pack. I’ve seen enough Hollywood movies to know that underdog has a pretty good chance though!
I’m wondering if you’ve thought to include (or been able to source) any of the Ukranian varieties? I’m thinking of ‘Black Prince’, ‘Ukranian Giant’, ‘Plodovaya’, ‘Shelli 150’, and others. It seems some of these may be highly bred vs many of our cultivars. I recall seeing somewhere a description of ‘Black Prince’ in particular suggesting it was a complex hybrid of some type. I don’t have ‘Black Prince’, but I do have several others. I don’t have anything rooted at present, but I could probably send you some scions next year if you’re interested.
Of the ones in your collection so far, I’m most interested to see how Gerardi shakes out. It’s so different in appearance than all others I’ve seen, it has to have something going on genetically. Louis Gerardi claimed it was a successful hybridization with macroura, I believe. USDA lists it as a nigra cross last I looked. How many licks does it take? The world may never know…
I’m focusing on cultivars offered commercially in the U.S. I need to have sales receipts to publish the ploidy determined for a specific cultivar from a specific nursery.
Marta sells (cuttings of) both the Ukrainian varieties Shelli and Galicia via Really Good Plants, and she has a CDFA nursery stock license. But, with her current business model she’s only listing stock available once or twice per year, and the most recent one was just last month. But she might be willing to make a special out of season sale to include those cultivars in this project.
Marta is a geneticist who is careful about claimed species. I’m seeking out retail plant sites and wholesale suppliers with suspicious claims of Morus species. If I end up with ploidy data that does not match their claims, I will first notify them and then after a reasonable amount of time publish an article stating their response, if any.
Well gotchas aside- I agree many nurseries are less than through or scrupulous in their claims- it’d be great to know more about the genus in part to better know how it might be shaped to our own ends.
I came across a source a few years ago espousing a rethinking of the rubra / alba dichotomy. Continents apart maybe justification enough for making a clear delineation, but I spose genetics might someday have something to say about it. They share ploidy, anyway, and cross readily. My education is merely at an undergraduate level, but I remember learning that the rough standard for differentiating species is viability of the 2nd generation, I.e. non- mule sterility. Maybe a rough approximation for something with clearly a lot of exceptions.
Someone (you @Richard ? ) posted this interest paper some time ago about the origins of Morus nigra.
Again, my plant science is a little elementary here, but basically they looked at 12n hybrids of alba x nigra and the syntax of their alleles (probably a term here I’m missing) is apparently similar enough that they readily form viable hybrids, suggesting that perhaps nigra came about through a curious spontaneous manifold doubling of ploidy. Wondering if you’ve read the paper @ Richard and what you’re thoughts are.
“Fairly regular meiosis of 22-ploid M. nigra and of the hybrid between M. migra and M. alba suggests that this highly polyploid form with 308 chromosomes may have originated by an increase in ploidy level of one and the same genome, with concomitant mutation for restricting multivalent formation. The bivalent formation between the chromosomes of M. nigra and M. alba points to the same conclusion. Had there been different genomes involved in the origin of 22-ploid…”
Continued>>>
“ However, Abdulaev and Djafarev (1962, 1965) succeeded in germinating self-pollinated seeds by artificial means. Seedlings raised in this manner are shown in Fig. 4a. Fig. 4 b shows a two-year old plant and Fig. 5 shows 308 chromosomes at mitotic metaphase in a young leaf of a 2-year old plant. This indicates that the seeds of Chart-tut form arising through self pollination may give rise to a 22-ploid plant similar in every respect to the population raised through vegetative propagation. The fact that seeds may be induced to germinate supports indirectly the hypothesis of Janaki- Ammal (1948) that the origin of this species took place through recurrent poly- ploidisation. The capability of seeds of Char-tut form to germinate artificially suggests that in the past propagation took place through seeds. However ancient the species M. nigra may be, in all probaritity, it has originated from the diploid
M. alba which is far more ancient than M. nigra.”
@hobilus
That paper was published in 1970 (Pak. J. Bot., 2 (1): 65-76). The authors provide an excellent report of M. nigra cytology. They also propose that M. nigra “probably originated by an increase in ploidy of diploid M. alba”. I believe they intended that statement to be read in the context of evolution, not as a single one-off. Their experiment is interesting although I don’t know if anyone showed it to be repeatable. Google Scholar only lists 2 citations for the paper.
Regarding the identification of different Morus diploids – what a pandora’s box that is! Contrary to gossip among fruit growers, M. alba and M. rubra are named for the color of their bark, not the colors of the fruit they produce. Also, it is clear that M. rubra is a western hemisphere species and M. alba was originally isolated in the eastern hemisphere. There are also other diploid M. species names floating around in the eastern hemisphere but the number is narrowing as nations swallow their pride and realize they have a race of M. alba.
Differentiating M. rubra, M. alba, and M. rubra x alba (in either order of cross) is still a difficult endeavor, in part because of the pollution of native M. rubra by M. alba in the past century. Although some have claimed to have a genomic test to distinguish them at present there is none. This is of no concern to me. I am only interested in testing ploidy to distinguish diploids, M. macroura, and M. nigra.
Reproductive isolation is a better way of thinking of species differentiation, of which hybrid sterility is just one possible mechanism. Populations can be prevented from interbreeding through many mechanisms; for example, geographic isolation (they grow in different areas), temporal isolation (they bloom at different times), mechanical isolation (for example, the pollinator for one species can’t reach the stigma of the other species), etc. For many species, multiple mechanisms are at play.
In flowering plants, sterility of hybrid offspring is probably a less important factor than in animals, mammals in particular. That said, it’s fairly common for plants to undergo chromosome duplication, generating a new population that can no longer produce fertile offspring with its neighbors. The same process can also restore fertility to an infertile hybrid, giving rise to a new species of hybrid origin. You can also have situations such as “ring species” where neighboring populations are interfertile, but the populations at opposite ends of the geographic range are too distantly related to interbreed, although this is more common in animals.
Today I finished the summer pruning of the mulberry cultivars (all in pots). The most aggressive of them by a long shot has been the AgriStarts Dwarf Everbearing. None of them turned out to be M. nigra except two ‘Persian’ I recently acquired from One Green World (not shown).
Are there any such hybrids available? Have their fruits been evaluated for quality? A berry with the flavor of nigra and the ease of care & propagation from alba would be quite a treasure.
