1 66 THE FLORA OF THE ALPS 



by Gremli as natives of Switzerland, all being also British 

 plants: P. densus, L., leaves opposite; natans, L., 

 floating leaves thick, coriaceous ; fiuitans, Roth ; colo- 

 ratus, Vahl (plantagineus, Ducr., Hornemanni, Koch); 

 rufescens, Schrad. (alpinus, Balb.) ; gramineus, L. (hetero- 

 phyllus, Schreb.), submerged leaves linear - lanceolate ; 

 lucens, L., leaves very large and shining ; Zizii, Roth. ; 

 crispus, L., leaves crisp, wavy; perfoliatus, L., leaves 

 cordate - amplexicaul ; pr&longus, Wulf., leaves oblong, 

 half-amplexicaul ; decipiens, Nol. ; pectinatus, L., leaves 

 very long, filiform ; marinus, AIL, spikes on long stalks, 

 alpine lakes ; compressus, L. (zoster cefolius, Sch.), stem 

 winged, leaves linear, half-amplexicaul ; acutifolius, Link. ; 

 obtusifolius, M. K. ; mucronatus, Schr. ; pusillus, L., spike 

 very few-flowered. 



2. ZANNICHELLIA, L. 



Flowers minute, solitary or in pairs, axillary, in a 

 cuplike sheath ; leaves submerged, linear. 



Z.palustrtSj L. (including pedunculate*,, Rchb.), Horned 

 Pond- Weed ; stem very slender, leaves opposite ; stagnant 

 water ; Switzerland, rare. 



3. NAIAS, L. 



Flowers unisexual, solitary or few, enclosed in sheaths ; 

 perianth o; stamen i; carpel i, with i ovule; leaves 

 linear, very narrow. 



N. major, All. (marina, L.) ; flowers dioecious, solitary, 

 leaves dentate-spiny ; stagnant water ; Switzerland, Pyr- 

 enees, rare. N. minor, All. (Caulinia fragilis, Willd.); 

 flowers monoecious, solitary or few, leaves nearly entire, 



