24 ENGLISH BOTANY. 
seen. Rare, and local in Ireland, where it occurs about Limerick, 
Dublin, Westmeath, and Mullingar. 
England, Scotland, Ireland. Perennial. Flowers not known in 
sritain. 
Fronds } to % inch across, more orbicular than many of the pre-_ 
ceding species, bright green above, generally purple beneath, with a_ 
tuft of numerous roots from a point towards the base of the frond, 
from which point radiate a number of veins containing spiral fibres. 
The flowers have never occurred in Britain or France, and seem to be | 
very little known. Reichenbach figures them as coming from the 
upper side of the frond. Lamarck, who is probably right, represents 
them as produced from a lateral cleft near the base. Both these figures 
have been copied on our Plate MCCCXCVII. 
Greater Duckweed. 
French, Lenticule a plusieurs racines. German, Vielwurzelige Wasserlinse. 
Section V.—WOLFFIA. Jaril. 
Fronds floating, herbaceous, not tailed, wholly destitute of root-_ 
fibres, and furnished with a membranous-edged basal cleft from which — 
the young frond is produced, which remains sessile and attached for a 
short time to the parent frond; cells of the epidermis bounded by 
straight lines. Flowers from a pit on the upper surface of the frond 
Ovary containing a single erect ovule. Fruit indehiscent, 1-seeded. 
SPECIES V—LEMNA ARRHIZA,. Linn. 
Reich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XIV. Fig. 14. 
Billot, F\. Gall. et Germ. Exsicc. No. 3478. ‘ 
Wolffia arrhiza, Wimm. Coss. & Gern. Fl de Par. ed. ii. p. 716. Welwitsch im 
Seemann’s Journ. Bot. 1865, p. 113. Trimen in Seemann's Journ. Bot. 1866, — 
p- 220. 
Wolftia Michelii, Schleid. Beitr. z. Bot. Vol. I. p. 233. 
Bruniera vivipara, F'ranchet, in Billotia, Vol. I. p. 25. 
I 
Fronds opaque, floating, cylindrico-convex above, and more so be 
neath, oval-oblong, entire, not apiculate or tailed at the base, destitu 
of roots; the under side with spongy tissue. Young fronds solita 
and sessile from the very base of the parent frond. 
Discovered in a pond near the railway station at Staines, Middlese 
by Dr. H. Trimen, in June, 1866, and afterwards near W aa 
Essex, by Mr. Traherne Moggridge. a 
2 
England. Perennial. Flowers unknown in Britain. 
4 
Fronds very minute, !; inch long by about half as broad, differing 
