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9
NOTES ON LEMXACEiE AND ON THE DISCOVERY OP
THE RAPHIDIAN CHARACTER IN SYSTEMATIC BO-
TANY.
By Geokge Gullivee, F.R.S.
Aithough our knowledge of the comparative structure of the Duck-
weeds has been much advanced during the last few years, we do not
find a corresponding progress in the descriptions and tigures of these
plants in our books* of systematic botany. The forthcoming plate of
JFoljfia, under the care of the worthy editor of tlie third edition of
' English Botany,' will, no doubt, be at least on a level with the pre-
sent state of science. As yet there have been added in that work only
the flowers of Lemna polyrrhiza to the old plates of the four species of
this genus ; while those important details of structure which are now,
through the memoirs by Hoffmann and others, well known as aflbrding
valuable diagnostic characters, are not figured, and the large vacant
space of each plate is left waste and \iseless. And hence, for a satis-
factory exposition of our own familiar and useful Duckweeds, w'e are
still obliged to consult, besides our great national Elora, the engravings
and descriptions scattered through various foreign and native periodi-
cal works, most of which have been so carefully specified in Dr. Trirnen's
valuable paper on TFolffia, published in a former volume of this Jour-
nal, as to relieve me of the task of citations.
In short, a fair account of the British Lemnacets is now wanting in
our books, and the present notes are intended as a small contribution
towards this desirable object, which involves a few little additions to,
and a revision of, some points respecting these plants and raphides
in the sixty-fourtb number of the third edition of ' English Botany.'
Use of Duckweeds.—As the popular and practical English mind is
wont to raise this question at the threshold, 'English Botany' is ready
there with its answer :— " Although pretty enough to excite general
interest, we has'e nothing to record of the uses of the species oi Lemna."
Too severe a sentence, surely, on even these abject and despised things,
and withal in sad disregard of that plea for the Duckweeds, long since
advanced in the case of L. minor, which proved the utility of one or other
of these apparently mean and worthless plants in the economy of nature.
For certain it is that the most common and abundant Duckweed may be
found, and recognized by its cell-characters, in the stomachs of young