Further to my recent posts about Elaeagnus, I think it will be informative for me to comment about PHYTOGEOGRAPHICAL REGIONS for plants.
I note that phytogeography is much favoured in some ‘floras’.  I have a copy of ‘Wild Flowers of Pakistan’ Nasir & Roberts (1995) to which I contributed 4 photos
(sent as slides but never returned, regrettably).
There is a section on ‘Phytogeographic Regions’.  The authors (based upon the work of Ali & Qaiser in 1986) state there are 4 recognized regions in Japan.   One of these they give as the Sino-Japanese – to which they assign Kashmir and NWFP (incl. parts of Hazara, Chitral, Astor).
When I read this, it came as a surprise to me, as I knew of hardly any plants common to both Japan and Kashmir.
According to the authors the ‘Sino-Japanese Region’ is a narrow belt extending from Japan, Korea, SW China westward through upper Assam, Taiwan, Bhutan, west Nepal and Himachal.  
Apparently, there are MANY Sino-Japanese elements in this ‘Himalayan’ zone (which was NEWS to me).  Yet, most of the examples given ARE NOT found in Japan. I suspect this is due to a combination of MISIDENTIFICATIONS and a MISUNDERSTANDING of old SYNONYMS and SPECIES NAMES USED BY MORE THAN ONE AUTHOR.
In most large countries in roughly the same part of the globe you will find a certain number of species in common, though this is hardly indicative of COMMON elements.   Also one needs to understand that Hooker’s FBI (which covered what is now Pakistan) had a NARROW view of species AND is OUT-OF-DATE.
Collet in Flora Simlensis frequently talks of ‘British’ species being found at Shimla, which subsequently have been recognised as belonging to DIFFERENT species altogether.
Kashmir’s flora and much of the NW Himalaya has a flora distinct from the wetter, eastern districts of the Himalaya.
Let me give some examples the authors of the above book CLAIM as ‘Sino-Japanese’:
Androsace umbellata – this is found in both countries and China, so qualifies but barely a ‘Himalayan’ species – more a one of the Indian plains…..
Boeninghausenia albiflora (Hk.) Reichb. ex Heynh. is found in Pakistan forests but in Japan there is only one species – B.japonica Nakai – syn. B.albiflora sensu Japon. NON Reichenb…  Oh dear!
Euonymus japonicus – yes, very common & much-planted in Japan – Stewart says PLANTED IN GARDENS IN PLAINS & LOWER HILLS FOR ITS FOLIAGE – SO NOT A NATIVE BUT A CULTIVATED PLANT!!!   How could this be included??
Geranium nepalense – this is v.common in the NW Himalaya but whilst there was a G.nepalense in Japan it was merely var. thunbergii – which is Geranium thunbergii, a separate species.  Oh dear!
Lonicera quinquelocaris – which I am familiar with from Kashmir is NOT listed in Japan!
Lysimachia japonica – yes, this plant is found in Japan but it is L.japonica Thunb. Stewart recorded L.debilis Wall. with yes L.japonica as a synonym but L.japonica Hk.f.  NON- Thunb!!  Oh dear, Oh dear….
Oxalis acetosella – yes, this is found in both countries but also Europe and Central Asia – so hardly ‘Sino-Japanese’….
Rhus japonica – I can find NO mention of this species in Stewart’s Catalogue of Pakistan plants!  I can find no mention of it in Flora of Japan either!!   According to The Plant List this is an unresolved name dating back to a 19th C publication on Nepalese Plants….  MIGHT be a synonym of R.chinensis…..
R.succedanea – is reported from both countries.   
Viburnum cylindricum – Stewart reports this as very rare (rather an odd choice) in Pakistan but NO record for Japan!!!!!
If these were the BEST examples, then MY assertion that there is NOT a Sino-Japanese ‘element’ to the Pakistan flora, seems pretty conclusive……
I am sure nobody wishes further examples…..