Yeah, for a while now, (i.e., in the past decade!) the Rockville tree has looked bigger and fuller than the Barnes tree.

I would hate to accuse a fine Philadelphia cultural institute of horticultural mismanagement, but I've heard it happens at the best of facilities. (har har har) I do wonder if this is a case of benign neglect versus codling to death. In plants susceptible to root rot, too much fertilization can tip them over the edge, although there's probably a fine balancing act, with too little keeping them from outgrowing death. One can imagine some "certified" or "trained" or "degreed" garden manager thinking all the established specimens at the Barnes would benefit from a spring dose of fertilizer. Who knows.

SO...now it's just down to the Rockville tree, the Baltimore tree, and the smaller South Jersey and NW DC trees. (the one just outside the entrance to Dumbarton Oaks). Oh wait, the Norfolk tree is still there right? I think there's still one on Staten Island, but I remember some on Long Island have frozen out over the years.

I don't think anyone should plant these on the east coast, but it's worth saying a friend of mine I've lost touch with...a very well known horticulturalist in the DC area...insists that they are mostly hardy enough for the area (DC), but they have to be planted on non-clay soil. And not just a little raised berm obviously, but the whole root run of a large tree. He said the one he planted a few years earlier would certainly have survived long term: he bought his house just for the soil. Apparently parts of Silver Spring, MD have a light, schist soil that drains very well. (that was what was Silver in the springs!) But he was selling his house to downsize and all the rare plants were removed. He drove me to one about 10-15' tall, a few blocks away. (IIRC this was the same tour where I saw the 80' Sequoia sempervirens in S.S. and a mature Dalbergia hupeana) Whether Silver Spring will someday be known as "land of the east coast Monkey Puzzles", eh, remains to be seen. ;-) I wouldn't bet on it. I first saw the Rockville tree 20 years ago and it has grown a lot. Maybe the soil there is somehow atypical. Most DC suburbs west of Silver Spring would be pure red clay until you got out to the mountains. I think it's more likely the tree itself is somehow atypical - an outlier with genes for better resistance to our very non-Chilean climate, weather and soil! That tree also, based on the size when I first saw it in 99, had to survive the winter of 94 when it went well below 0F. I'd say at least -6F at that location if not lower. My childhood garden near Dulles airport was -10F or so. Lots of destruction to a budding young plant collector's collection LOL. The Potomac froze so solid you could walk from DC to VA. Last time that has happened...not even the 'polar vortex' winters were that cold.