Hi all. I just had a quick look at the accepted names list on the Maple Society website. I am very pleased that Acer palmatum has been split into A. palmatum and A. amoenum as that is clearly a logical division between two easily differentiated species and I believe has been the accepted division used in Japan for quite some time. (Similarly A. takesimense and A. tenuifolium are recognised as species rather than sub-species of related maples.) A. amoenum is further divided into varieties as follows: The varieties amoenum and matsumurae (and their named forms) are well known but Acer amoenum var. nambuanum is not. I can find very little apart from the mere mention of the name on google, a search of this forum only brings up discussion of the accepted names list and there is no information about it in Yano's 'Book For Maples' (although it is included in the species list). Does anyone have knowledge of this maple variety and what its characteristics are?
@maf good morning M, I have no direct knowledge of this one, but found this link that might help you. Acer palmatum subsp. amoenum - Japanese maple | The Dawes Arboretum D
This is from J-L Hélardot's website, but it's in latin and the translation into French is a bit... surprising sometimes : Untitled Document It's listed here, but no photos or descriptions. Could be useful if you want to use the name of taxon in Japanese, forsearching on the web for instance : ムクロジ科 学名 - 野山の花たち 東北と関東甲信越の花
Thanks Alain, the google translation from Latin into English is no less interesting, not quite sure where the bearded men come into it! I think these types of documents need a human translation to elucidate which sadly is beyond me. I'd already seen the second link but hadn't thought to use the Japanese characters to start another search. However, after going through the first couple of pages of results very little information is forthcoming regarding description and no photographs. A couple of the links provide a geographic origin but they disagree with each other so cannot even count on that information.
I don't know var nambuanum, Doug Justice here at UBC might know about it (being a member of the species group). I can give you the sources, it is from the Bulletin Tokyo University Forest, 1965, pp25, but I didn't find anything with a quick google scholar search. Could ask Dan Crowley if he's got a description, if you like (or you could ask yourself if you know him). He'll either know or know who to ask.
Thanks @emery, I don't know Dan Crowley but if it is in any way possible for him to find a description it would be much appreciated. Also, if @Douglas Justice has anything to add it would be equally appreciated. Strange how there is so little info readily available about this variety yet the other two vars are so well known.
Dan got back to me with a copy of Aceraceae in Flora of Japan (K. Ogata). There is a brief description of var nambuanum, which I will cite (it's a photograph, so I can't copy and paste; wonder why this didn't show up in a search?): var. nambuanum ... Japanese name: Nanbu-koha-momiji Leaves small, 3.5-5.5 cm long, 5-8.5 cm wide, usually 7 lobed with simple regular serrations. Japan: Pacific Ocean side of N. Honshu (from Iwate to Miyagi Pref.). Endemic. Compared to A. amoenum, the leaves are much much smaller, and amoenum is 5-,7-, 9- lobed (usually 7). I guess there is a historical differentiation, leading to a local nomenclature, based on the distinctive morphological difference.
Thanks @emery, my take on that description is that leaves are similarly shaped to var. amoenum but, as you say, notably smaller. As far as I know Flora of Japan is not digitised and available on the web, it is certainly not on efloras.org.
