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Hydrocharitaceæ, Lemnaceæ, Pontederia- 

 ceæ, Potamogetonaceæ, Gentianaceæ (Lim- 

 nanthemum), Nymphæaceæ 



by C. H. Ostenfeld — Copenhagen. 



Hydrocharitaceæ. 

 Blyxa Thouars. 



1. B. sp. (octandra (Roxb.) Planch.?). 



It is impossible to determine the collected specimens of Blyxa because 

 they are sterile. 



Rice-field near Lem Dan. 



Area (of B. octandra): Tropical Asia and Australia. 



Halophila Thouars. 



2. H. ovalis (R. Br.) Hook, fil., Fl. Tasman. II, p. 45; B.Balfour, On 

 the Genus Halophila, Transact, and Proc. of the R. Soc. Edinburgh vol. XIII, 

 1879, p. 290; Caulinia ovalis R. Br., Prodr. Fl. Nov. Hollandiæ p. 339; 

 H. ovata Gaud., in Freycinet, Voy. Bot. p. 429, t. 40, f. 1 ; Hook, f., Fl. 

 of British India V, p. 663. 



The few present specimens which are sterile, belong to f. minor 

 (Zoll.) Aschs., Linnæa 1867, p. 174 (Lemnopsis minor Zollinger, Verzeichn. 

 1854, p. 75). 



Between Koh Riat and Koh Mesan, in 3—5 fathoms water (coral-sand). 

 Area: Shores of the Indian, Malayan, Australian and Pacific Oceans (from 

 the Canal of Suez to Luchnan Islands (Japan)). 



3. H. decipiens Ostf., n. sp. 



Leaves oblong-elliptic, their ventral surfaces hairless, but their 

 dorsal surfaces and the margins covered with very fine, short, uni- 

 cellular star hairs or teeth; the same hairs are found on the out- 

 side of the scale- and spathe-leaves ; from the midvein of the foliage 

 leaves 6 — 9 lateral veins pass on each side outwards to the intra- 

 marginal vein; the petioles Vs — 1 time as long as the laminæ. 



Plants monoecious, flowers unisexual, 1 male and 1 female 

 flower enclosed in the spathe-leaves, corresponding in regard to 

 structure etc. very closely with those of H. Baillonis (see: Theo. 



