On June 26th we drove over to Thompson’s Trout Pond. We took the old flat-bottomed boat, and with one slab board for a paddle, steered slowly over the whole surface of the lake,—a beautiful, clear little mountain mirror, with good-sized fish swimming about. I searched along the shores for the long-desired Purple-Fringed Orchises, but still without success. Fleur-de-lis grew abundantly about the lake; and in the little dents and bays among the sedges and cat-tails, I found the Yellow Spatter-Dock or Cow-Lily (_Nymphæa_), so named in the time of Christ by the ancient herbalist, Dioscorides, who first gave it the Greek name _Blephara_, and later, in Latin, _Nymphæa lutea_ and _Nenuphar citrinum_. It was known in England in 1500 as Yellow Nenuphar or, Water Lily. The swamp birds are tame and saucy here. Paddling our boat into the reedy shores among the alder bushes, where they were nesting, they seemed to take no alarm at our approach, but stood their ground pouring forth beautiful liquid notes. In one place near the centre of the lake, we crossed an expanse of deep water where long rootlets of the Water Persicaria (_Polygonum amphibium_) supported glossy carmine, lance-like leaves, which swayed gracefully on the surface of the swelling waves as we approached. These strange deep-water weeds send forth rich crimson or pinkish flowers a little later, seeming fairly to stain the lake. I had never seen this species before growing in such depths of water. It is a species of the Buckwheat Family, and a near cousin of the barnyard smart-weed and the knot-grass or door-weed. The generic name, _Polygonum_, comes from the Greek, meaning “many knees.” It is so called on account of the swollen joints of some of the species of this family. The leaves of the Water Persicaria are brilliant crimson on the lower surface, and with age and exposure the upper surface turns deep Indian-red. These plants were rooted at least fifteen feet below the water’s surface in the mud. They may be found, too, along the shallow shores of Pownal Pond. They also grow in ponds and lakes far northward to Quebec and Alaska, and as far south as New Jersey and Kentucky, and westward to California. They thrive at an altitude of two thousand feet, in the lakes of the Adirondacks, blooming there, as a rule, in July and August. Thoreau observed this species in the lakes of the Maine woods, during his journey in 1853.