What cows should not eat...

At last, a mystery solved.

For months I've been eyeing a plant in one of the planter boxes on the eastern side of the terrace. It came up near the jewelweed, and I had no idea what it could be. Neither did anyone on the plant ID forums I belong to. We wus stumped.

Now that it's in bloom it is obvious: white snakeroot, Argeratina altissima (formerly Eupatorium rugosum). Famous for killing Mrs Lincoln (mother of Abraham), by way of her cow. Milk sickness was passed on to humans and calves by cows who'd grazed on the plant,  and apparently killed thousands of people in the 19th century before they figured out the cause. I wonder if it still does, occasionally?

I know this silly plant. It's in bloom all over the New York City right now and crowds the paths in woodland areas. When I was Litter Mobbing in Prospect Park we were surrounded by it for weeks. It is all over the abandoned backyards on either side of us. But I wasn't expecting it in a planter box on the terrace, and had never paid special attention to the young leaves, and so failed to recognize it. This shady spot has inadvertently become the native corner. I like it.

(Speaking of woodlands: there'll be an edible botanicals walk this Saturday in Central Park, from 12pm - 2pm. Details to follow.)