I've noticed a lot of "confusion" about what sub-group a tree belongs to. Most of the confusion seems to revolve around the Shirasawanum group. What is the criteria for defining a plant as a shiraswanum?? Who decides what a plant really is - or is not?!? Thanks,
Acer palmatum is easily told by having leaves with 5 or (usually) 7 deeply cut lobes, whereas Acer shirasawanum has leaves with 9-13 shallowly cut lobes. More difficult to distinguish is Acer japonicum, which has very similar leaf shape to Acer shirasawanum, but it has downy shoots, whereas Acer shirasawanum has glabrous (hairless) shoots. Best observed in spring, as by late summer, the hairs on A. japonicum shoots can wear off. In the wild, Acer japonicum has a more northerly / higher altitude distribution, Acer shirasawanum a more southerly / lower altitude distribution.
Saying this without looking it up (never very wise) but aren't shirasawanum's flowers held upright, whereas japonicum's flowers are pendant? -E
Yep, Emery, you get the point, what I understood from my readings is that one of the key factors (if not the main) to classify (and sometimes re-classify) a cultivar between japonicums and shirasawanums is this characteristic. I need to looking it up also (I don't have on hand my JM books in this moment). Nelson
Thanks for the info. I keep discovering that cultivars I bought as Palmatums are actually Shirasawanums. Green Elf, for example. Mine is labeled as a Palmatum. If its that easy to tell, it looks like the vendors could get it right!
