KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55- N :0 5. 205 



Petagna, Inst. Bot. II, 1787, 289. — P. palustris Teesdale, Träns. Linn. Soc. V. 

 1800, 43. — P. distachyus Bellardi, Stirpes novse etc, in Mémoires acad. Turin, 

 1804, 447. — P. augustanum Balbis, Miscellanea bot., in Mémoires acad. Turin, 

 1804, 330. — P. lancijormis Roemer et Schultes, Syst. vegetab., 1818, 512. — P. 

 paucifolius Opiz, Böheims phän. und crypt. Gew. 1823, 23. — P. crassipes Kitaibel, 

 in Cham., Adnot. etc. 1815, 5. — P. Proteus heterophyllus Cham. et Schl., Linnaea, 

 1827, 202. — P. gracilis Wolfg. ap. Schultes, Mantissa III, 1827, 355, ex Kihlman, 

 Bot. Not. 1887, 84. — P. nigrescens Fries, Mantissa III, 1842, 17. — P. longe- 

 pedunculatus Mérat, Revue de la Fl. paris. 1843, 494. — P. Kochii Lang, Fragm. 

 Herz. Verd. in Flora, 1846, 471. — P. varians Morong ap. Fryer, Notes on Pond- 

 weeds in The Journ. of Bot., 1889, 33 p. p. — P. Wolfgangi Kihlman, Herb. Mus. 

 Fenn. ed. 2. 1, 1889, 128. — Fig. 102. — 



Although Linné in his short description of this plant bas not mentioned either 

 floating or petioled leaves, the species, however, should be considered a coriaceous- 

 leaved Potamogeton. 



The habitat of this plant, you will observe, is shallow lakes and ponds, shallow 

 rivulets and inside the edge of the reed of larger lakes, where the water is calm. 

 In such places P. gramineus thrives and fruits abundantly and prolongs the stem 

 by short branches of as far as the fifth or sixth rank, all endowed with coriaceous 

 leaves. But the plant also accommodates itself to olher conditions. On trying to 

 invade deeper water and more rapid or large rivers, it limits the development of 

 floating leaves to a minimum and returns to a more primative stage. Ampliating 

 the surface of the submersed foliage as a compensation for the floating leaves it 

 stretches the internodes and the peduncles instead of prolonging the stem by branches 

 in the top. By this adaptation the deepwater-form (var. lacusiris [Fr.]) and the river- 

 forms (var. jluvialis [Fr.]) arise, with a habit very different from the shallow- water- 

 form (var. heterophyllus Fr.). In sueh forms of adaptation I have met with primary 

 peduncLes of as much as 35 cm in length when the length of it otherwise is a few 

 cm. A ny change of the stem anatomy, however, does not take place by that ad- 

 aptation. It remains steadily the same under different externa! conditions. 



E. Fries has thought that the Swedish Nordland fluvial form of the species 

 ought to be established as main-form (a. graminifolius), since Linné first during his 

 Laplandian travel (1732) has obser ved and described the plant. In Species plantarum 

 though, among other amendments of the earlier description, Linné has made the 

 addition that the species is annual and as habitat of the plant stated: »in Europge 

 fossis et paludibus», from which it is clear that he properly has had in view a slender, 

 young plant from ditches. The reference to Raji Synopsis will not mean more 

 than that Linné has considered his Lapland plant to answer to the figure 3 (t. 4) 

 of the Synopsis, regarded by some to represent P. obtusifolius, by others, again, P. 

 acutifolius, both of them not at all occurring in Lapland. There is no reason to 

 reject the Linnean name, and a misdetermination in Linnérs herbarium does not 

 alter the dignity of the good old name. 



The arrangement of the forms made in his Novitse fl. succicse, 1828, E. Fries 



