C. japonica var. radicans is a botanical designation for trees with a columnar habit. Presumably here in the West a vegetatively propagated clone is being dispersed under that name, in which case a new cultivar name should be coined. If part or all of these are also or instead being raised from imported seeds it should be kept in mind that there could be some variation in resulting seedlings.

'Sekkan' is a tree form with yellow foliage mostly on top, lovely in a sheltered position but sometimes scraggly and discolored in open places. New here yet one in Seattle was already over 17' tall a few years back.