188 153. AROIDEX.—154. LEMNACER. 
This is the common Acorus of China, and is very variable in 
size. The larger forms have been confused with A. Calamus, 
Linn., from which they are readily distinguished by the absence 
of a distinctly thickened midrib to the leaves and spathe, a more 
slender spadix, and a shorter spathe. A. Calamus seems to be 
rare in China, as I have seen but two specimens. Owing to the 
confusion of names, only specimens actually seen are here 
quoted, except one on the authority of Dr. Engler. 
154. LEMNACE. 
(By C. H. Wuicnr, A.L.S.) 
1. Lemna minor, Linn. Sp. Pl. ed. l, p. 970; Lour. Fl. 
Cochinch. p. 550; Hance, in Journ. Linn. Koc., Bot. xiii. (1872) 
p. 129; Bretschneider, Early Res. p. 181; Hegelmaier, Die 
Lemnaceen, p. 142; Debeaux, Fl. Shangh. p. 62; Franch. et 
Savat. Enum, Pl. Jap. i. p. 12; Hook. f. Fl. Brit. Ind. vi. 
p. 556. 
Curmi: Peking (Bretschneider, 777 !); Kxaxasv : Shanghai 
(ex Debeaux); CukKrIANG (ex Debeaux); Howakowa (Hance). 
Herb. Kew. 
“ Frequent in S. China. Common also in N. China” (Bret- 
schneider). 
Temperate and warmer regions of the world. 
2. Lemna paucicostata, Hegelmaier, Die Lemnaceen, p. 139; 
Mart. Fl. Bras. ii. 11. p. 20, t. i. fig. 5; Franch. et Savat. Enum. 
Pl. Jap. ii. p. 12; Hook. f. Fl. Brit. Ind. vi. p. 556. 
Lucuvu AnonrPELAGO (Wright, 824!). Herb. Kew. 
Throughout the tropies. 
This has been confused by many authors with Lemna minor, 
Linn., from which it differs in its less symmetrical frond and 
erect ovule. 
3. Lemna polyrhiza, Linn. Sp. PL ed. 1, p. 970; Flor. Dan. 
t. 1589 ; Syme, Engl. Bot. ed. 3, t. 1397 ; Kurz, in Journ. Linn. 
Soc. ix. p. 267; Hook. f- Fl. Brit. Ind. vi. p- 557. 
Spirodela polyrrhiza, Schleid. in Linnea, xiii. p. 392, et in Ann. Sci. 
Jat. 2"* sér, xiii. p. 148; Maxim, Prim, Fl. Amur. p. 266; Mart, Flor, 
Bras. ii. 11. p. 21, t. i. fig. 6; Hegelmaier, Die Lemnaceen, p. 151, t. xiii, 
figs. 10-16, tt. xiv.-xv.; Franch. et Savat. Enum. Pl. Jap. ii, p. 13. 
