The Botany of Iceland - 01.12.1942, Qupperneq 122

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JOHS. GRONTVED
Potamogeton gramineus X P- perfoliatus.
P. nitens Weber var. heterophyllus Fr., Babington, 1871, p. 334.—Gronlund,
Isl. Fl., 1881, p. 104.—Rostrup, 1887, p. 183.—P. gram. X P. perfol., Stefánsson,
Fl. ísl., ed. 1, 1901, p. 19.—Ibid., ed. 2, 1924, p. 22.—O. & Gr., 1934, p. 12.
Flora Dan. tab. 1807.
Specimens of this presumed hybrid from Laugar near Reykjavík are kept in
H.H. (coll. Kr. and C.G.). There are also records from some few other places:
Melstaðir (A.F.) and Helgavatn, N. (St.St.), cp. E. Rostrup, 1887, p. 183; Hvítár-
vellir, Stafholt, W. (A.F., cp. E. Rostrup, loc. cit.) ; Eyðar, E. (H.J., 1896,
no. 330).
Nothing definitive can, however, be said about these records.
Potamogeton lucens Linn.
P. lucidum, K. & M., 1770, p. 205.—P. lucens, Vahl, 1840, p. 374.—Babington,
1871, p. 334.
Recorded by K. & M., loc. cit., and entered in all the best lists, cfr. Babington,
1871, loc. cit. No specimens are in evidence and it should certainly be excluded
from the Icelandic flora.
39. Potamogeton natans Linn., Sp. pl. ed. I (1753) p. 126.
K. & M., 1770, p. 205.—Babington, 1871, p. 334.—Strömfelt, 1884, p. 118.—
E. Rostrup, 1887, p. 182.—P. natans L. f. prolixus Koch, Stefánsson, Fl. ísl.,
ed. 1, 1901, p. 18.—Ibid., ed. 2, 1924, p. 21.—P. natans L., O. & Gr., 1934,
p. 12.
Flora Dan. tab. 1025.
Fig. 35. Potamogeton natans L.