On Thu, 9 Feb 2012 18:08:33 -0800 (PST), Higgs Boson wrote:
Is this too fragile a plant?...Or...? Never saw anything so strange
as the R to L progression.

You probably don't remember Dutch Elm disease... it spread in a linear fashion
down many, many streets. What happened is that the trees had formed natural
root grafts over the years, and when the fungus was introduced into one tree.
it would spread down the road via the root graphs.

That's the first explanation that pops to mind -- root grafting.

If it were indoors in an office, the first explation I'd explore there was
someone dumping their coffee cup or similar in one end of a planter
consistently. g

Kay