Potamogetones novi. 147 
6. X P. prussicus. (Potamogeton alpinus Balbis X perfoliatus L.) Hag- 
ström, l. c., p. 103, fig. 8—12. 
Caulis 0,5—1 m altus simplex vel ramosus teres, internodiis 6— 
15 cm longis; folia submersa elongata basi + rotundato vel + cordato- 
rotundato, apice semper rotundato, margine sparse denticulato; stipulae 
intermediae vel ad P. alpinum magis spectans; pedunculus 5—6 cm longus 
aequalis; spica 20--30 mm longa floribus Sterilibus. 
Two formseries are to be distinguished: 
I. series abbreviata Hagström, 1. c.. p. 104. 
Folia submersa breviora latiora basi + cordato. 
Forma darkehmensis Hagström, l. c., p. 105. 
Folia ca. 100 mm longa, ca. 23 mm lata, basi rotundato-cordato, ob- 
iusa, superiora subcoriacea folia summa floralia petiolata, stipulae inter- 
media, stigmata oblonga iis P. alpini similia. 
Only one growing-place is hitherto known, viz. ,in der Angerapp* 
at Darkehmen, East-Prussia, where it is. collected by H. Kuehn. 
IT. series alpinifolia Hagstrom, 1. c., p. 104. 
Folia submersa pro ratione prioris longiora, saepe 200 mm et ultra, 
angustiora basi + rotundato-lanceolato (P. alpino similiore). 
Forma pelplinensis Hagstróm, ]. c., p. 105. 
P. alpinus Balb. var. obscurus II virescens Caspary ex Asch. et Graeb- 
ner, Synopsis der mitt. FL, I, 1897, 312, pp. — P. alpinus Balb. var. 
d. virescens Asch. & Gr., in Graebner, Potamogetonacae, 1907, 74, pp.: 
caulis habitu P. perfoliati. 
Folia submersa quoad formam fere omnino ut in P. alpino sed margine 
denticulis unicellaribus caducis instructa; folia floralia lanceolata subses- 
silia, summa subcoriacea. 
West-Prussia, Kreis Preussisch-Stargard bei Pelplin im Fersefluss, 
Where it has been collected by Professor R. Caspary, 1. IX. 1886. 
7. X P. argutulus. (Potamogeton gramineus L. X nodosus Poir.) Hag- 
ström, l. c., p. 106, fig. 13—14. 
Folia submersa lanceolata denticulis sparsis cito deciduis, apice paulo 
quam in P. gramineo L. obtusiore. Stipulae foliorum caulinium iis P. no- 
dosi similes, longiores et citius putrescentes quam in P. gramineo. Struc- 
tura anatomica caulis ad P. gramineum fortiter vergens. 
Two formseries occur: 
Series gramineifolia Hagström, l. c., p. 106. 
Caulis ramosus, folia ramea lanceolata sessilia. 
Forma puyensis Hagstróm, l. c., p. 107. 
Caulis ca. 0,5 m altus ramosissimus, tenuis; folia ramea submersa 
lanceolata obtuse cuspidata minima, folia natantia numerosa, forma et 
magnitudine cum iis P. graminei congruentia coriacea; fructus rari, me- 
diocres, majores quam in P. gramineo, quoad formam iis P. nodosi 
Simillim i, 
. »Gallia: Vienne in stagno dieto ,de la Puye' 10 julio 1900. E. 
Simon“. 
10* 
