I think knowing the ages with any certainty is unfortunatly ....impossible...My instict ...if those sizes are correct, that the orangeola is possbly the oldest believe it or not!!!...but how old is anyones guess.
As far as the dead Koto No Ito what you have left is a basic red or green seed grown generic JM used as rootstock possibly even another atro...you will never know and it will most likely be NOT "unusual" or "special" in any way except to you ...David

Thanks David. I have an idea of the small ones, but the larger ones like the Oreangeola and the Atro i haven't figure out. I'm guessing are 4-10 yrs. Plus, I thought it may be a good challenge to all you J. Maple lovers/Conneseur

I was also trying to find out if there is a formula per plant that can help with age determination.

I think you will find it pretty difficult to make any specific correlation between size and age - certainly there is no "formula" one can follow. There are simply too many variables that would affect size - height of graft, field versus container grown, soil and planting conditions, climate, any pruning, training or staking that has been used to guide the growth, fertilizing, etc. And growth rate is pretty flexible for many J. maples - some are extremely slow growers, others quite a bit faster.

You might find it easier to make some rather rough generalities based on canopy spread and branch development, as well as trunk diameter, but it's going to be pretty much just a guesstimate. I'd agree that the dimensions stated for 'Orangeola' indicate a somewhat mature specimen. I'm also curious as to what a variegated 'Atropurpurem' may be - the term is used somewhat generically for unnamed upright redleafed cultivars and is probably more accurately used as a forma rather than as specific cultivar. To my knowledge, there are no variegated forms of atropurpureum.

I also would assume the "atropurpureum" is not grafted ( seed grown) or grafted from another so called atropurpureum...seed grown ...As has been stated you NEVER know what you will get with seeds and it is possible it was a generic red leafed "atropurpureum" seed that grew variegated and was propagated...but then whether seed or grafted it really should be renamed cause it is NO LONGER an atropurpureum... just as a bloodgood and pixie are not atropurpureum's but were "begot' from atropurpureum...GG is correct that term of variegated atropurpureum is a oximorom IMHO...but she is also correct that the term itself is somewhat vague being a 'generally' red upright palmatum JM a name that as far as I am concerned is basically useless I have one BTW ( not variegated) and do call it an atropurpureum only to give it a name...and it's sounds neater than just a japanese red maple ;>)I assume many others feel the same way and dealers who are basically trying to make money will sell more of a named tree. David

I might restate something ..I believe the pixie is an offshoot or sport of a bloodgood not atropurpureum but has it's lineage from such. Many of todays cultivars are selected seedlings from generic japanese red maples now known as atropurpureums. JD Vertrees also states the term atropurpureum has lost all meaning and yes there was such a tree I believe originally in Europe...but most likely what 99% of those claiming to have them in this country is not one of them...a relative maybe be not a "cloned" cultivar ...David

The name Variegated Atropurpureum was told to me when purchasing the tree. As the leaves are Chartreuse with white edges (like a butterfly)then turns to a washed out red by end of summer to fall. The owner of the nursery also told me it was a graft and he was pleasantly surprised at how well it turned out as he didn't think it had much of a chance when he first grafted it. I'll post a picture of it.

Here is a link that might be useful: {{gwi:1034704}}

That is interesting. I've heard of variegated reds before ('Yubae'is a purple red leaf that has brighter red variegation I believe, although the variegation is not reliable).

This seems quite different, however. I am curious, is the red color it's fall color? Because if I'm not mistaken 'butterfly' and 'beni shichihenge' have some slight red fall color, although not outstanding by any means. So, if that's the case, it is likely just another variegated variety.

And as far as aging the trees, most likely the best way would be to measure the trunk size. Even with that, it would be very difficult to guess an age within about 5 years.