The Botany of Iceland - 01.12.1942, Blaðsíða 209
THE PTERIDOPHYTA AND SPERMATOPHYTA OF ICELAND
207
Flor. V—VI; fr. mat. VII—VIII.
Max. height: 65 cm; average : 45 cm.
Geogr. area : Am.: Labrador to Hudson Bay.—Greenl.: W. 63°—74° 18'. E. 63°28'
—75°.—Eur. : S.; northern and arctic parts; central Eur. mts.; Ural; Spitsbergen ;
Novaya Zemlya.—Asia: Arctic Asia eastward to the Yenisei.
Betula nana X B. pubescens.
B. intermedia Thom., Gronlund, Isl. Fl., 1881, p. 92.—B. alþestris Fr. = B. odorata
X B. nana ?, H. Jónsson, 1896, p. 338.—B. nana X B. odorata, Stefánsson, Fl. ísl.,
ed. 1, 1901, p. 74.—B. nana L. X B. pubescens Ehrh., Ibid., ed. 2, 1924, p. 84.—
I.Ó., 1927, p. 423.—O. & Gr., 1934, p. 52.
Flora Dan. Suppl. 1, tab. 37 (B. humilis Hartm.), tab. 2852 (B. intermedia Regel)_
Icelandic: Skógviðarbróðir.
Hybrids between B. nana and B. þubescens are very frequent where the two
parent species grow together, and these hybrids may often occur abundantly.
In many cases it may be very difficult to decide whether we have a small-leaved
form of B. þubescens or a hybrid before us, especially if the specimens are sterile
(cp. also I.Ó., loc. cit.).
165. Betula pubescens Ehrh., Beitráge zur Naturkunde, VI (1791)
p. 98.
B. alba, K. & M., 1770, p. 210.—B. subalþina Larss. Th.M.Fr., Carroll, 1867,.
p. 108.—B. intermedia Thom., Babington, 1871, p. 326.—B. glutinosa Fr.,
Ibid., p. 327.—B. odorata Bechst. var. þubescens, var. tortuosa Regel, var.
þarvifotia Regel, and B. alþestris Fr., Gronlund, Isl. Fl., 1881, p. 92—93.—
B. odorata Bechst., Stefánsson, Fl. ísl., ed. 1, 1901, p. 74.—B. þubescens Ehrh.,
Ibid., ed. 2, 1924, p. 84,—O. & Gr., 1934, p. 52.
Flora Dan. tab. 2917 (var. parvifolia Regel).
Icelandic: Skógviður, Ilmbjörk. Danish: Hvidbirk, Dunbirk. English: Common
Birch.
Much confusion has prevailed in the naming and conception of the Icelandic
“forest-birch”. It is true that it is exceedingly variable, which may suggest a division
into several separate forms or varieties; but on the other hand there seems to be
no possibility of finding distinct characters which are stable enough for setting up
such varieties. The name Betula þubescens as used here may be interpreted as a col-
lective name. In future it might be possible through cytological investigations, to
clear up the problem.
Betula þubescens is the only tree which forms woods in Iceland. In former times
ít was far more widely distributed, but as already mentioned (p. 66) the birch-
woods have been vastly diminished, and are now to be found especially in more
sheltered places, at the heads of the fiords, at the bottom of valleys and on hill-
slopes. Scattered specimens may, moreover, be found in localities of very different.
nature, often low of stature or with prostrate trunks. It is found in most parts of
the country, only in S. and S.W. it seems to be conspicuously less frequent, and it
seems to be almost absent in the Skagafjörður valley. The marked insular climate
south of the great jökulls is no doubt unfavourable for the development of the
• wooc* > a's0> the action of man has here exercised a stronger influence than
ín t e other parts of the country, and even the orographic conditions of large areas.
m . Iceland are obstructive for the development of the birch wood.