LEMNACEA. 437 
y. ‘minima, Hegelm. Lemn. p. 138. 
CairorniA.—Souta Mexico, without locality (Hahn).—Ecvapor ; Cui. Hb. Kew. 
2. WOLFFIA. 
Wolfia, Horkel; Schleid. in Linnza, xiii. p. 389; Benth. et Hook. Gen. Plant. iui. p. 1001. 
Twelve species are defined by Hegelmaier; they inhabit Europe, India, Tropical 
Africa, and Tropical and Temperate America. Some of them are so small as to be 
almost microscopic. | 
1. Wolffia columbiana, Karst. Botan. Unters. i. (1865), p. 103; Hegelm. 
Lemn. p. 122, t. 1. figg. 1-13. 
Sout Mzxtco, near the city of Mexico (Hahn). —CoLomBiaA; VENEZUELA. Hb. Kew. 
2. Wolffia lingulata, Hegelm. Lemn. p. 132, t. 4. figg. 31, 32. 
Sourn Mexico, in the vicinity of the city of Mexico (Hahn). Hb. Kew. 
This was found growing with Wolffia gladiata, Lemna minor, L. valdiwiana, and 
Azolla caroliniana. 
In the Kew Herbarium is a specimen labelled by Hegelmaier “var. minor cum 
Ricci nutanti adherens.” 
3. Wolffia gladiata, Hegelm. Lemn. p. 133, t. 3. fig. 24. 
Sourn Mexico, in the neighbourhood of the capital, growing with W. gladiata 
(Hahn). Ub. Kew. 
(The TrivurIDE#, consisting of two genera and about sixteen species, are apparently 
not represented within our limits, though they range from Brazil to Venezuela. Else- 
where the Order is only at home in Tropical Asia. | | | 
Order CLVI. ALISMACEE. 
Alismacee, Benth. et Hook. Gen. Plant. iii. p. 1003. 
Aquatic and marsh herbaceous plants, inhabiting all save the frigid regions. Including 
the Butomew, regarded by some botanists as an independent Order, there are twelve 
genera and about sixty species. 
1. ALISMA. 
Alisma, Linn. Gen. Plant. n. 460; Benth. et Hook. Gen. Plant. i. p. 1004. 
Of this genus there are ten species, having nearly the same range as the Order; 
A. plantago is found in Europe, Asia, Africa, America, and Australia, but it is not 
known from within our limits. 
1. Alisma tenellum, Mart. in Rem. et Schult. Syst. Veg. vii. p. 1600; Kunth, 
Enum. Pl. iii. p. 149; Seubert in Mart. Fl. Bras. iii. 1, p. 105, t. 13. fig. 2. 
Echinodorus parvulus, Engelm.; A. Grey, Man. Bot. Northern U.S. 1865, p. 492. 
