374 NaiadecE. [Ruppia. 



2. P. pectlnatus, L. Sp. PI. \2j (1753). 



Thw. Enum. 333. Ruppia subsessilis, Thw. Enum. ;^'^2,. C. P. 3531, 

 3214. 



Fl. B. Ind. vi. 567. 



Stem filiform, copiously distichously branching, forming 

 with the 1. tassel-like masses when taken out of the water; 1. 

 all submerged, alt., 1-4 by oVtV i"-. filiform, acute, opaque, 

 1-3-veined, or lower 5-veined, stipules adnate to the l.-sheath, 

 tips free; scape with the spike 2-3 in., filiform, much longer 

 than the 1., not thickened upwards, fl. few, in few very distant 

 whorls, minute, green; sep. suborbicular ; drupelets \ in. long, 

 turgid, dimidiate-obovoid, smooth, slightly compressed, shortly 

 beaked, dorsally rounded, and obscurely 3-keeled. 



Lakes and backwaters, often brackish, near the coast ; locally 

 abundant. Kalutara ; Chilau; Negombo Lake, very abundant; Jaffna. 

 Fl. Dec. -Feb. ; pinkish. 



Throughout the North Hemisphere; common in England. 



Thwaites's Ruppia subsessi/is (C. P. 3214) is from Jaffna, and is merely 

 a small form of this. 



3. RUPPIA, Lin/i. 



Submerged, brackish-water plants; rootstock creeping, 

 much-branched ; stems slender, dichotomously branched ; 1. alt. 

 or subopp., filiform, formed of 2 parallel tubes, sheath elongate, 

 narrow ; infl. a very small, 2-fld., shortly peduncled spadix, 

 enclosed in an axillary, spathulate, compressed, hyaline spathe, 

 ped. lengthening after flg. ; fl. minute, sessile, 2-sexual; 

 perianth o; anth. 2, sessile, cells reniform, nearly free, slits 

 extrorse, pollen tubular; ov. 4, stipitate, obliquely narrowed 

 into a short style; ovoid, stigma peltate, ovule solitary, pendu- 

 lous; achenes 4, very small, ovoid, long-stipitatc, endocarp 

 hard; seed pendulou.s, uncinate, embryo macropodous. — Sp. 2; 

 I in FL B. Ind. 



R. rostellata, Koch, ex Reichenb. Ic. Crit. Cent. ii. 66 (1824). 

 1"1. B. Ind. vi. 568. Griff. Ic. PI. Asiat. iii. tt. 257-759. 



Whole plant forming tangled submerged masses of filiform, 

 leafy, flaccid stems and branches; 1. 2-4 in., very slender, dull 

 olive-green; ped. ;^-i in., not spirally coiled; fl. minute, 

 binatc, stipes of ov. rapidly lengthening up to i in. long after 

 flg. and spreading; achenes jV in. long. 



In brackish lagoons on the coast ; very rare. Only seen from 

 Matalan, N. Prov., where it was collected in i88g by Mr. Nevill. Fl. 

 Feb. 



Throughout Europe and Asia. Occurs in England. 



