93. LEMNACE.E. 94. POTAMOGETONACE^E. 349 



with not more than 3 large seeds. Thickets in the Undercliff, 

 Isle of Wight. Mr. Hambrough. P. VI. E. 



Order XCIII. LEMNACE^E. 



Fl. monoecious, 2, in a spath, but without a spadix. Perianth 

 0. Stam. 1 2, distinct. Ovary 1-celled. Style short. Stigma 

 simple. Fr. bladdery, not bursting. Seeds with a coriaceous 

 ribbed testa. Floating, leaflike, small ; no distinction of st. or 

 leaf. 



1. LEMNA. Spath membranous, urn-shaped. Stam. 1 2. 

 Anth. 2-celled, didymous (cells bilocular?). Fl. from just 

 below the edge of the frond. Increasing chiefly by buds. 



1. LEMNA Linn. Duckweed. 



1 . L. trisulca(L.} ; fronds thin pellucid elliptic-lanceolate tailed 

 at one end serrate at the other, roots solitary. E. B. 926. R. 

 vii. 15. Roots tipped with a sheath. Fronds half an in. long, 

 proliferous at right angles. "Filaments recurved, filiform." 

 Schleid. Plants truly annual, producing gemmae which survive 

 the winter as in the other species. Stagnant water. A. VI. 



2. L. minor (L.) ; fronds obovate compressed opaque, roots 

 solitary. E. B. 1095. R. vii. 14. Fronds 1 2 lines long, nearly 

 flat beneath, of a compact texture. Filaments recurved, filiform. 

 Stagnant water. A. VI. VII. 



3. L. polyrrhiza (L.) ; fronds roundish-obovate compressed, 

 roots many clustered. E. B. 2458. R. vii. 15. Spirodela 

 Schleid., Endl. Fronds half an in. long, green above, purple 

 beneath. " Filaments narrowed below." Schleid. Stagnant 

 water. A. Fl. have not been seen in Britain. 



4. L. gibba (L.) ; fronds obovate nearly flat above hemispheri- 

 cal and spongy beneath, roots solitary. E. B. 1233. R. vii. 14. 

 Telmatophace Schleid., Endl. Fronds 1 2 lines long, remark- 

 ably gibbous and cellular beneath. " Filaments recurved, dilated 

 in the middle." Schleid. See an excellent account of the germi- 

 nation of this plant, by Mr. Wilson, in Bot. Misc. i. 145. t. 42. 

 Stagnant water. A. VI. VIII. 



Order XCIV. POTAMOGETONACE^. 



Fl. perfect or imperfect. Perianth inferior, 4-parted, or 0, or 

 replaced by a membranous spath. Stam. free, 1, 2 or 4. Ovaries 

 4, distinct, each with 1 ovule, and 1 sessile stigma. Fr. a drupe 



