^04: CLI. LEMNACE^ (bROWN). [Wolffia, 



Frond with a colourless process from the lower edge of 



the bud-cavity. 



Frond always distinctly denticulate on the margin ; 



colourless process about 4 times as long as the 



frond and not half as broid . . . . \. W. repanda. 



Frond entire, or occasionally denticulate ; colourless 



process about twice as long as the frond and § 



as broad 2. W. Delilii. 



Frond without a colourless process. 



Frond 2-3 lin. long, very thin, pellucid, undulated . 3. W. Welwitschii. 

 Frond minute, ^^ lin. long, thick. 



Frond nearly as broad as long, fiattish above . 4. W. MicJielii. 

 Frond much longer than broad, convex above . 5. W. cylindracea. 



1. "W. repanda, Hegelmaier, in Journ. Bot. 1865, 113. Frond 

 minute, J iin. long, J lin. broad, elliptic-oblong, thin, flat above, con- 

 vex beneath (con-vex on both sides, ex Welwitsch), denticulate on the 

 margin, producing from the lower edge of the cavity from which the 

 young frond emerges a flat linear colourless process, resembling a root, 

 about 4 times as long as the individual fronds. Flower in the centre 

 of the upper surface of the frond. Fruit about J lin. long, ellipsoid. 

 — Hegelmaier, Monogr. Lemn. 129, t. 4, fig. 20-30, and in Engl. Jahrb. 

 xxi. 301 ; Durand & Schinz, Conspect. Fl. Afr. v. 485 ; Engl. & Prantl, 

 Pflanzenfam. ii. iii. IGl, and 151, fig. 101, H ; Rendle in Cat. Afr. PI. 

 Welw. ii. 92. 



Xiower Guinea,. Angola : Loanda ; plentiful in deep ponds near Bemposta, 

 mixed with' Lemjia paucicostata, Hegelm., Welwitsch, 205 ! 



In two of Hegelmaier's figures and in that of Engler & Prantl's Pflanzenfamilien, 

 the curious root-like process is erroneously represented as arising near the middle of 

 the undersurface of the young frond; this is never the case. This process is, in 

 reality, nothing more than the stalk tl;at attaches the young frond to its parent, 

 vv^hich, after their separation, elongate-; in a remarkable manner to fully 4 times the 

 length of the frond, and somewhat resembles a root, but has no root cap, and cannot 

 in any sense be regarded as a root. 



2. W. Delilii, Schleid. in Linnxpa, xiii. 390. Frond very small, 

 1 lin. long, J lin. broad, elliptic or elliptic-oblong, thin, fiat, very 

 obtusely rounded at the end, entire or occasionally minutely denticulate, 

 producing from the lower edge of the cavity from which the young 

 Irond emerges a broad fiat linear colourless process, about twice as long 

 a,s the individual fronds, and | as broad. Flower seated in the upper 

 surface of the frond a little to one side of the middle, and nearest the 

 ba^al end, according to Hegelmaier's figures. — Kunth, Enum. iii. 4. 

 W. hyalina, Hegelmaier, Monogr. Lemn. 128, t. 4, figs. 11-19, and in 

 Engl. Jahrb. xxi. 301 ; Engl. Pfi. Ost-Afr. C. 423 ; Engl. & Prantl, 

 Pflanzenfam. ii. iii. 164, and 154, fig. 101, F, G ;* Durand & Schinz, 

 •Conspect. Fl. Afr. v. 485. Lemna hyalina, Del. Fl. ^gypt. 27. 



Ifile jfiaad. Darfur: Surudj district, in fresh-water pools on Gebel Barkin, 

 Ffutid (ex Hegelmaier). Kordofan : Bara, Pfund, 235 ! 



