430 NAIADACEJE. [TBJGLCCHIN. 



1. T. palus'tre, L> ; leaves filiform ^-terete throughout, fruit clavate, 

 carpels 3 slender long attached to the axis by a point. 



Marshes and wet meadows, N. to Shetland ; ascends to 2,000 ft. in the High- 

 lands; Ireland; Channel Islands; fl. June- Aug. Stem swollen at the base, 

 stoloniferous. Leaves 2-12 in., flaccid, upper surface faintly grooved. Scape 

 slender. Raceme elongating after flowering, pedicels short. Perianth purple- 

 edged. Anthers purple. Fruit appressed to the scape. Carpels terete at 

 the back, narrowed below, axis 3-quetrous. DISTRIB. Europe (Arctic) 

 (excl. Greece), N. Africa, N. Asia, N.W. India, N. America. 



2. T. marit'imum, L. ; stems tufted thickened at the base, leaves 

 slightly flattened at the tip, fruit oblong of 6 separable carpels. 



Salt marshes, N. to Shetland ; Ireland; Channel Islands; fl. May-Sept. Larger 

 and stouter than T. palus'tre ; scape curved; raceme longer, not dense-fid., 

 nor so long in fruit ; flowers larger ; fruit not appressed to the scape, and 

 carpels grooved at the back. DISTRIB. Coasts of Europe (Arctic) (excl. 

 Greece, Turkey), N. Africa, salt districts of Asia, N. America. 



2. SCHEUCHZE'RIA, L. 



A small marsh herb. Rootstock creeping. Leaves erect, slender. Scape 

 leafy ; flowers racemose, bracteate. Perianth-segments 6, herbaceous, re- 

 flexed, connate at the base, persistent. Stamens 6, hypogynous, filaments 

 short ; anthers long, narrow, adnate to the filament, extrorse. Ovary of 3 

 carpels connate at the base, stigma sessile ; ovules 2-3 in each carpel, basi- 

 lar, anatropous. Fruit oS. 2-3 inflated spreading follicles. Seeds 1-2, erect, 

 ovoid, testa coriaceous. DISTRIB. N. and Mid. Europe (Arctic), N. Asia, 

 Rocky Mts. ETYM. Two Scheuchzers, Swiss botanists. 



S. palus'tris, L. ; leaves J-terete, sheaths turgid. 



Marshes, rare, Salop, Notts, Chester, York, Perth ; fl. July. Rootstock long, 

 slender, clothed with old leaf-sheaths. Leaves 6-10 in., with dilated brown 

 sheaths and a pore at the tip. Scape stout, curved. Raceme lax, few-fld. ; 

 pedicels much lengthened in fruit. Perianth-segments linear-oblong. Ripe 

 carpels large for the plant. 



3. POTAMOGE'TON, L. 



Aquatic herbs. Leaves submerged and translucent, or floating and 

 opaque, alternate or opposite ; stipules connate, membranous or 0. 

 Flowers 2-sexual, in axillary or terminal spikes, proterogynous. Perianth- 

 segments 4, small, herbaceous, clawed, persistent, valvate in bud. Stamens 

 4 ; anthers subsessile on the claw, 2-celled, extrorse. Oarpels 4 (rarely 1) 

 free, sessile, stigma subsessile ; ovules solitary, ascending, campylotropous. 

 Drupelets 4 (rarely 1), small, green. Seed curved round a lateral process 

 from the cell, testa membranous ; radicular end of embryo inferior, large, 

 cotyledonary narrowed hooked or involute, plumule immersed. DISTRIB. 

 Temp, regions, more rare in trop. ; species about 50. ETYM. Trorajuos, a 

 river, and ysiTcav, a neighbour. 



