Lemna. | CLI, LEMNACEZ (BROWN). ‘201 
1. LEMNA, Linn.; Benth. et Hook. f. Gen. Pl. iii. 1001. 
Flowers seated in a cavity at the margin of the frond, enclosed in a 
‘minute membranous spathe, very minute, very rarely seen in some of 
“the species. Stamens 1-2; anthers 2-celled ; cells opening by trans- 
verse slits—Fronds small or minute, with one or more roots from their 
under surface, floating on still waters, thin and flat, or flat above and 
more or less convex beneath, suborbicular, elliptic, oblong, obovate or 
‘Spathulate in outline, entire, or in one species minutely denticulate on 
the margin; roots tipped with a distinct sheath-like root-cap. 
Species about 16, Widely distributed in all the warm and temperate parts of 
doth hemispheres, 
Each frond with several roots . : z é - 1. LZ. polyrhiza. 
Each frond with one root only. 
Fronds subrotund, 14-8 lin. in diam., underside very 
convex and greenish-white . : . . 2. L. gibba, 
Fronds elliptic or elliptic-oblong, 3-2} lin. long, 
rather thin, flat above, not very convex beneath. 
Root-cap obtuse ; root-sheath not winged . . 3. DL. minor, 
Root-cap acute ; root-sheath winged . . . 4. L. paucicostata. 
Fronds elliptic, 3-2 lin, long, obtusely keeled above 5. L. equinoctialis. 
Upper Guinea. Lower Niger: Onitsa, Barter, 583! ; 
Nile Land. British East Africa: Meshra, on the Ghazal River, Schweinfurth, 
1281! Mpororo district, Stuhlmann (ex Hegelmaier). 
Widely distributed in most warm and temperate regions, 
Linn. Soc. xvi. 685; Durand & Schinz,Conspect. Fl. Afr. v. 484; Schwein- 
furth in Bull. Herb. Boiss. ii. App. ii. 53, 105; N..E. Br. in Dyer, Fl. 
