The Duckweeds (Lemna).
The Duckweeds—Shakespeare's "Green mantle of the standing pool"—are plants that are well-known to everybody, and consequently very few persons know anything of them. This is a paradox; but they are so common and so small that the average man or woman is content to know them in the aggregate, and cannot condescend to a more intimate acquaintance with individuals, or with the different species, yet like many other small things "unconsidered trifles" they are very interesting to the botanist; for these are among the smallest and simplest of the flowering plants. Taking up two or three plants from one pond and comparing them with some from another piece of water, we shall probably find a difference in them; but they are all possessed of a more or less flattened green body that floats on the water, and which we shall be inclined to call a leaf. It is not a leaf, however, but a plant that produces no leaves, though it has roots and flowers. To be more accurate we will call it a frond, from whose undersurface there goes down one or more simple unbranched roots, and in clefts of whose margin are simple flowers. The flower consists of an envelope or spathe (see page 15), within which is a bottle-shaped pistil, with one or two stamens beside it. Some authorities contend that the pistil and each of the stamens is really a distinct flower similar to those in Arum. These flowers are so minute that they are rarely seen, and so are thought to flower only occasionally. The plant is chiefly multiplied by the production of new fronds from its edges. The four species figured give the whole of the genus, so far as Britain is concerned; but three others are known in foreign waters. The differences in the natives may be thus briefly enumerated:—
