Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
1(54
ön the subject, the author gives (p. 32) a detailed account of the
niorphology of the Potentilla-flower, and there shows that, P.
fruticosa, like P. bifurca and, probably, P. daimrica too, is „imperfect
dioeeious".
P. fruticosa ön the island of Oland, however, is purely dioeeious,
i. e., all the flowers ön the same individual produce either pollen
alone or seed alone, irrespective of whether the suppressed sex of
the flower is represented bv möre or less evident rudiments, or
not. As far as I know, this was first discovered bv Professor (i.
Lagerheim, who mentioned the fact to me in the spring of 1906.
My surmise is, that the same condition of thing exists in northern
Gotland — from which Vestergren, Johansson and Hägg, in
1908, described the habitat of P. fruticosa — and in the
extra-Scandinavian localities.
I shall give below a brief summary of the results of the
observations respecting P. fruticosa — and, speciallv, its flowering
-that I have been able to make ön the southern „alfvar"1 of Oland,
during the summers of 1906, 1907, 1909 and 1910 and in the
winter of 1910 — 11.
HABITATS.
I wish to mention the following points from Wolf’s monography:
The place of origin of the Potentilla-genus was the circum-polar
land of the tertiary period, and, even to-day, its chief area of
distribution is that sea-divided belt of land in the northern hemisphere
that lies between the tropic of Cancer and the eternal ice of the
polar regions. At the close of the tertiary period, when the climate
underwent a change and the continents were mapped out, a new
phase began in the story of the development of the Potentilla-genus:
some species die out; others, wilh greater capability of adaptation,
survive: some take other forms of development, difTerent in the
three continents. The now-existing groups of species belong to the
two following categories: l) Groups poor in species; the species
being relatively constant and showing little tendency to hybridism.
These — the palæotvpical -— are the oldest that have survived.
1 The ..alfvar" is an extensive limestone table-land occupying nearlv the whole of
the south of the island of Öland, boasting a wealth of wild, almost dwai fed species,
but almost incapahlc of cultivation. There is also a smaller tract of the same
charader in the middle of the island. near the town of Borgholm.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
