ACANTHACEA, ~ 501 
1. Elytraria tridentata, Vahl, Enum. i. p. 106; DC. Prodr. xi. p. 64; Griseb. 
Fl. Brit. W. Ind. p. 451; A. Gr. Synop. Fl. N. Am. ii. p. 324. 
Elytraria frondosa, E. ramosa et E. fasciculata, H. B. K. Nov. Gen. et Sp. ii. pp. 234 et 235. 
Elytraria bromoides et E. microstachya, CErst. in Vidensk. Meddel. 1854, pp. 114 et 115, t. 3. 
figg. 1-6. 
Elytraria pachystachya, (rst. loc. cit. p. 116, t. 3. figg. 9-16? 
Elytraria caulescens, Ledeb. Ind. Sem. Hort. Dorp. 1820; DC. Prodr. xi. p. 63. 
Verbena squamosa, Jacq. Hort. Schoenb. i. p. 8, t. 5, fide Nees. 
Elytraria apargiefolia, Nees in DC. Prody. xi. p. 65. 
Arizona; New Mexico.—Mexico and CenrraL AMERICA, common.—Southward to 
Buenos AYRES, and in T'rinrpap and Cusa. Hb. Kew. 
3. NELSONIA. 
Nelsonia, R. Br. Prodr. Fl. Nov. Holl. p. 480; Benth. et Hook. Gen. Plant. ii. p. 10738. 
One herbaceous species :— 
1. Nelsonia campestris, R. Br. Prodr. Fl. Nov. Holl. p. 481; Benth. Fl. Austr. 
iv. p. 543; Endl. Iconogr. t. 79. 
Nelsonia rotundifolia, R. Br. loc. cit. 
Nelsonia tomentosa, Dietr., N. canescens, Nees, N. pohlii, Nees, et N. nummulariefolia, R. et S. in 
DC. Prodr. pp. 65-67, cum synonymis omnibus, fide Bentham loc. supr. cit. 
Nelsonia villosa, Girst. in Vidensk. Meddel. 1854, p. 118, t. 4. figg. 3-6. 
Almost everywhere in the Tropics, including CentraL America. Hb. Kew. 
4. HYGROPHILA. 
Hygrophila, R. Br. Prodr. Fl. Nov. Holl. p. 479; Benth. et Hook. Gen. Plant. ii. p. 1075. 
Herbs or half-shrubs. About fifteen species, widely dispersed in the tropics. 
Bentham and Hooker regard some or all of the following forms as varieties of 
H. salicifolia, Nees, a species that is common in Tropical Asia and Australia; but 
we are not clear which; therefore we leave them under the names given by Nees in 
DeCandolle’s ‘ Prodromus.’ 
1. Hygrophila costata, Nees in DC. Prodr. xi. p. 88; Seem. Bot. Voy. ‘ Herald,’ 
p. 178. 
Souta Mexico, Orizaba (Bottert, 628); Guatemala, Mazatenango (Bernoulli); Nica- 
raqua, Chontales (Yate, 213); Panama, Chagres (Fendler, 198, 202), banks of rivers 
(Seemann, 411).—Southward to Braz. Hb. Kew. 
2. Hygrophila lacustris, Nees in DC. Prodr. xi. p. 86; A. Gr. Synop. Fl. N. 
Am. ii. p. 324. 
Ruellia lacustris, Ch. et Schl. in Linnea, v. p. 96. 
Fioripa; Louisiana; Trxas.—MeExico, Jalapa (Schiede & Deppe). 
