257 

 MONOCOTYLEDONES. 



HYDROUHARIDACEAE. 



Key to genera. 



1. Freshwater herb 

 Salt water herb 



2. Stems branched 

 Plant stemless ... 



3. Leaves whorled... 

 Leaves scattered 



4. Leaves linear, sessile ... 

 Leaves ovate, petiolate 



5. Leaves serrate at the tip 

 Leaves acute, entire 



6. HalopMla. 

 3. 

 4. 



1. Hydrilla. 



2. Lagarosiphon. 



5. 

 5. Ottelia. 



3. Vallisneria. 



4. Blyxa. 



1.— HYDRILLA. 



1. H. verticillata, Royle ; Hook. f. Fl. Brit. Ind. v. 659. Pools 

 along the Lienchow River. Fl. August. 



S.— LAGAROSIPHON. 



1. L. Roxburghii, Benth. ; Hook. f. 1. c. 659. Marshy pools 

 on hills above Pat-heung, Hongkong New Territory ; 

 Lofoushan. Fl, October. 



3.— VALLISNERIA. 



1. V. spiralis, Linn. ; Hook. f. 1. c. 660. Lienchow River. Fl. 

 December. 



4.— BLYXA. 



1. B. Eoxburghii, Rich. ; Benth. Fl. Hongk. 347. In water- 

 courses at the racecourse, Little Hongkong, Shunwan, 

 and Chaiwan Gap, Hongkong ; near Kuntong, Hongkong 

 New Territory ; Swatow ; Hoifung. Fl. white, Septem- 

 ber — January. 



5.— OTTELIA. 



1. 0. alismoides, Pars.; Hook. f. 1. c. 662. Lantao Island, 

 Taipo, and Sanwai, Hongkong New Territory ; Hoifung ; 

 Whampoa ; Sanning ; West River ; Fukwing near Hong- 

 kong on the Canton River. Fl. white, August. 



6.— HALOPHILA. 



1. H. ovata, Gaud. ; Hook, f, 1, c, 663, Kowloon Bay, Hongkong. 

 Fl. . 



.?1515 



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