in Thoreau’s Journal:

The milkweeds, or silkweeds, are rich flowers, now in blossom.

The Asclepias syriaca, or common milkweed; its buds fly open at a touch. But handsomer much is Asclepias pulchra, or water wilkweed. The thin green bark of this last, and indeed of the other, is so strong that a man cannot break a small strip of it by pulling. It contains a mass of fine silken fibres, arranged side by side like the strings of a fiddle-bow, and may be bent short without weakening it.