Water milfoil.

August 16.

Myriophyllum ambiguum, apparently var. limosum, except that it is not nearly linear-leafed but pectinate, well out how long?

H. D. Thoreau, Journal, August 16, 1857

See July 29, 1859 ("The water milfoil (the ambiguum var. nutans), otherwise not seen, shows itself. This is observed only at lowest water.") and August 16, 1856 ("Am frequently surprised to find how imperfectly water-plants are known")

August 16. See A Book of the Seasons,  by Henry Thoreau,  August 16

 

A Book of the Seasons,  by Henry Thoreau

"A book, each page written in its own season,

out-of-doors, in its own locality.”

~edited, assembled and rewritten by zphx © 2009-2021