The Botany of Iceland - 01.12.1942, Blaðsíða 213

THE PTERIDOPHYTA AND SPERMATOPHYTA OF ICELAND
211
Icelandic : Tjarnablaðka. Danish : Vand-Pileurt. English : Floating Persicaria, Willow-
weed.
In Iceland this species seems to be exceedingly rare, being found in two places
only, viz. Syðri Garðar on the peninsula Snæfellsnes, W. (H.J., 1897), and at
Gaulverjabær, in Flói, S. (H.J., 1907, and 1911). It has been recorded by König
& Miiller, loc. cit., and is entered in all the older lists, evidently on K. & M.’s
authority. Babington, 1871, declares that he has no knowledge of any localities.-—
Specimens from Gaulverjabær, collected 26.VII.1907, have flower-buds, and the same
is the case with the specimens collected at
Syðri Garðar 26.VII.1897. See fig. 78. The
Icelandic specimens found belong to f.
natans Mönch, having glabrous stem-leaves
and ocreae; the floating leaves have long
petioles.
Life-form: HH (Hydrophyte).
In lakes and ditches, brooks with slowly run-
ning water; on wet soil.
Flor. VII.
Length of shoots up to 72 cm.
Geogr. area: Am.: N. Am., Quebec to
Alaska, southward to Kentucky, Colorado,
Calif., Mexico.—Eur.: Fær.; E.S.I., through-
out Europe, outside the arctic regions.—•
Asia: N. Asia, temperate regions; India.
—S. Africa.
171. Polygonum aviculare Linn., Sp. pl. ed. I (1753) p. 362.
K. & M., 1770, p. 207.—Babington, 1871, p. 325.—Gronlund, Isl. Fl., 1881,
p. 86.—Stefánsson, Fl. ísl., ed. 1, 1901, p. 80/—Ibid., ed. 2, 1924, p. 91.—
O. & Gr., 1934, p. 54.
Flora Dan. tab. 803.
Icelandic: Blóðarfi, Hlaðarfi. Danish : Vej-Pileurt, Honsegræs. English : Knot-grass,
Door-weed, Bird-grass.
Even if the form and size of the leaves, the stature, etc. may be very different
in the Icelandic specimens, the characters of the flower and the fruit seem rather
constant: the perianth being split nearly to the base, and the achenes somewhat
flattened trigonous. Some of the specimens appear to correspond well with the
description of P. heteroþhyllum Lindm. var. boreale (Lge.) Lindm., in Svensk bot.
tidskr. Vol. 6, 1912, p. 691.
Common in most parts of Iceland, except in the central highland, from which
part ít has not as yet been recorded. Evidently the records do not by far give a
true picture of its entire distribution in Iceland.
Life-form: Th.
Around inhabited places, weed in gardens, on roads and foot-paths; sandy sea-
shores ; around hot springs and on the banks of brooks issuing from these.
Flor. VI—VIII; fr. mat. VII—VIII.
Max. height: 60 cm ; average: 15 cm.
Geogr.^area : (coll. spec.) Am. : Throughout N. Am.—Greenl. : (P. heteroþhyllum)
^0°. E. 60°.—Eur.: Fær.; E.S.I.; throughout Europe.—Asia : Temperate
parts.
Fig. 78. Polygonum amþhibium L.
14*