Shimpaku is not a cultivar. Its the japanese word for Chinese juniper.
From the looks of the foliage it looks like my itoigawa shimpaku foliage. Kishu tends to be a little more corse and a blue green color
Perhaps this excerpt from Wikipedia will shed some light on your confusion.
“The Juniperus chinensis is one of the top species used in the Japanese art of bonsai, referred to as "Shimpaku." Among the multiple cultivars of Shimpaku found in Japan, the most desirable due to its tight, fine foliage and excellent growing habits, is the "Itoigawa" variety”
Shimpaku is what the Japanese have called Juniperus chinensis (chinese juniper) for centuries.
As you mentioned, there are selections of Shimpaku (Itoigawa, kishu, tohoku, and many others.) which are regional variants that have been been collected for centuries and propagated as “cultivars”
One thing that makes matters more difficult
Is that Itoigawa refers to Shimpaku that were collected from the mountains of the Niigata prefecture in Japan. Within Itoigawa there is a spectrum of foliage characteristics from extreme fine to more coarse. So not all itoigawa is created equal.
I Chinese juniper is the parent plant . Unique from other junipers to be listed as a separate plant type . Shimpaku is a named cultivar of Chinese juniper . Therefor it is recognized as having unique characteristics and growth habit from the parent plant . Recognized by the plant world as stated by Dirr wiki and the American conifer society . The naming of a cultivar requires proof and paperwork . Someone has done that so it is a named recognized cultivar of Chinese juniper . Said cultivar is native to Japan and obviously has been there for a long time . As the Japanese can attest to . I am unaware what to refer to the other 2 as . Looks like they are variations of shimpaku as described by the Japanese . I see no reference to them being separate cultivars of CJ They apear to be variations of shimpaku as noticed or cultivated by the Japanese . I suppose you could say they are Chinese juniper cultivar shimpaku sub variant ~~~~~. As stated by the Japanese. .Perhaps this excerpt from Wikipedia will shed some light on your confusion.
“The Juniperus chinensis is one of the top species used in the Japanese art of bonsai, referred to as "Shimpaku." Among the multiple cultivars of Shimpaku found in Japan, the most desirable due to its tight, fine foliage and excellent growing habits, is the "Itoigawa" variety”
Shimpaku is what the Japanese have called Juniperus chinensis (chinese juniper) for centuries.
As you mentioned, there are selections of Shimpaku (Itoigawa, kishu, tohoku, and many others.) which are regional variants that have been been collected for centuries and propagated as “cultivars”
One thing that makes matters more difficult
Is that Itoigawa refers to Shimpaku that were collected from the mountains of the Niigata prefecture in Japan. Within Itoigawa there is a spectrum of foliage characteristics from extreme fine to more coarse. So not all itoigawa is created equal.
Im currently growing mine out from rooted cuttings that bought and will be training them as shohin bonsai.Any advice on care guide? Things to be aware of. Best practices, like/dislikes
Very interesting vid like you say . I guess the Japanese refer to all scale junipers as shimpaku . Interesting that the word is not that old . But it all makes sense . We sometimes forget world travel is fairly new to mankind . So on there islands fir all there history they just started referring to there junipers by the area they came from . And there different features might not even been aware there were similar plants in China . At least on a wide spread scaleEvidently the Japanese refer to any Juniperus species with scale like foliage as shinpaku
So rocky mountain juniper (not a juniperus Chinensis) would be considered a shinpaku as well to the Japanese