But BB is a recent shrub, not 20 years old. Or is it?

Luis, I believe you are right..... have to read better. LOL

They are arborescence, right?

Annabelles will go white to brown... now i’m in a guessing game Mme Emile Mouillere LOL

They look like H. macrophylla to me, not arborescens, but I can't help as to the cultivar.

I grew Mme. Emile Mouillere for years in my old garden but mine never turned purple. I don't know of any white flowered mac that turns purple as it ages......I'll have to do some research :-)

Thanks everyone!

To confirm, yes, it's H. macrophylla (not H. arborescens).

Also, it was purchased 20 years ago so it's a lot older than Blushing Bride.

@hyed thank you for that picture! Here in Georgia Blushing Bride keeps reblooming, but I haven't seen the flowers dry well on the shrub. Its fun to see that it ages beautifully elsewhere.

I am pretty sure it's not Mme. Emile Mouillere because her sepals have a deckled edge and I read on Hydrangeas Plus that they age specked pink.

Any other leads?

I've checked through my resources and I'm not sure I have any difinitive leads. First, there are not all that many white mopheads, or at least those that have been around for 20 years. And there are so many factors that will influence the coloring as the flowers age that you won't find many absolutes stated about that phenomenon - it will be extremely variable depending on location, siting, soils and weather.

About the closest I can get for you is 'Soeur Therese' (Sister Theresa), which has been around for decades and will age to a pinky-lavender, that could conceivably darken to purple under the right conditions.

Hi Hills can you tell us how large HxW these Hy get ... and what is your take

Hi Hyed, The are 4' tall and my take lines up with gardengal, that they are likely 'Sister Theresa'.

Both Mallet and Dirr describe the aging flowers in a way that best matches with 'Sister Theresa':
-Mallet says it keeps its flowers until first frost and that they turn sea green in autumn (this lines up with the color of the flowers where the sun doesn't hit them). Mallet was writing from Normandy, France, so may not color well there, but we have the same green in the shade.
-Dirr says flowers become green tinted red when ready to dry and this lines up closer to what I saw at my mother in law’s.

Thankfully there aren’t that many white H. macrophylla mopheads that would have been around 20 years ago and in reading the descriptions of, for instance, ‘Le Cygne’, ‘Mme. Emile Mouillere’, ‘Regula’, ‘Schwan’, ‘Woodworth White’, I’m certain it’s none of those, so when I start second guessing ‘Sister Theresa’, I go through the process of elimination again and arrive right back at ‘Sister Theresa’. Phew. Hydrangea detective work is fun and stressful! Thanks for everyone’s input!