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Lemna.'] civ. PisxiACEiE. 477 



the nucleus. Radicle at the opposite extremity from the Jiilam, 

 — Floating frondose plants^ minute and usually lenticular or 

 with large lobed fronds. 



k 1. Lemna Linn. Duckweed 



i. ' 



Hi; 



SpatJia membranaceous, urceolate. Stam, 1—2, distinct, each 



bearing a 2-celled didymous ajither (the cells bilocular?). 

 J'rMiY utricular. '" -. -.^ . » 



'/«ce of 



floating 



far mor 



clefts of the parent frond ~ioMch, growing out on 2 opposite sides 

 into new plants, and these again producing offspring in the same 

 imj, while still attached to their parent, present a most curious 

 appearance. ~^a.m&: X^fiva, of the Greeks, it is said from 

 \imc, a scale. 



1. L. trisulca L. {Ivy-leaved D.) ; fronds thin elliptic-lan- 

 ceolate caudate at one extremity, at the other serrate roots 

 solitary. E. B. t. 926. ' 



Clear stagnant waters. Less frequent in Scotland than in England 

 0. 6 7. — Fronds 1_| of an inch in length, pellucid at the margins', 

 reticulated. Roots sohtary, calyptrate at the extremity, as in most of 

 the genus. Stamens 2. Ovary with a single ovule. Seed solitary 

 transverse, attached by a short stalk to the bottom of the utricle. 



2. l^. minor L. {lesser D.) ; fronds nearly ovate compressed 

 roots sohtary. E. B. t. 1095. ' 



BlE 

 tOtt' 



Iril Stagnant waters, common. ©. 7. — About a line or a line and 



tors a lialt long, of a rather thick and succulent, but compact texture 



recoJf shghtly convex beneath. This is the most abundant of all the species' 



covering the surface of ditches and harbouring numerous insects and 

 mollusca?,the food of ducks and other waterfowl, whence the Eno-lish 

 name o^ Duckweed. The young fronds constitute the Lemna <^Mza 

 ot the l^rench authors. Stamens 1. Or«ry 1-ovuled. The w^ncZe is 

 single-seeded ; seed transverse, with its hilum " directed towards the 

 narrow end of the frond :" Wilson. 



3: L. polyrhiza L. {greater D.) ; fronds obovate-rotundate 

 ^ coinpressed, roots numerous from the same point. E. B. t. 2458 

 ^^ bpu-odela Schleid. 



l-'l Stagnant waters. Rare in Scotland: near Glasgow. Flowers 



y ;f "«7, in Britain. ©. _ The largest of all the species, half 



„# dn inch long and nearly as broad, succulent, firm, faintly striate 



p: a little convex below, where, and at the margin above, the frond 



^' ' js of a deep purple colour. Spiral vessels are conspicuous throughout 

 > the whole plant ; but in all the other species there are either none 



Jr tney are evanescent. Boots numerous from a central point' 

 Starnens 2; filaments tapering below. Ovary with 2 erect ovules 

 Ihe fructification of this species has not been observed. 



