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1(54
minutes and 4 hours. The opening of a flower can take place at
a greater rate at the beginning than afterwards, or the reverse.
In consequence of the yellow colour of the petals and of the
great number in which the blossoms appear ön the bushes, the
flowers of P. fruticosa (which in contradistinction to those of
Ra-nunculaceæ are non-lustrous), are visible at a great distance to the
insects. Honey is obtained from the nectariferous disk which is
enlarged between the calyx and the gvnophore.
As is usually the case in windy localities, the number of the
species ön the „alvar" of Öland which are pollinated only bv
insects is small. Amongst this little number of species is P.
fruticosa. The visiting insects that I have observed belong to the
fol-lowing groups:
The humble bee: When the wind happens to be very strong
this insect is the most persevering visitor. it seems to prefer the
cf-flowers.
Diptera: Begin their work at sunrise. Are the most industrious
visitors af the species.
Ants: Live in the knolls of P. fruticosa and rob honey from
the flowers.
The flowers last longer than in the case of P. argentea, anserina
and erecta. Those that I have observed have fallen during the
course of the fourth day. They are open and without protection,
both when it is cloudy, when it rains, and during the night.
After the flowers have bloomed, the gynophore of the Q-flowers
swells, and the sepals bend themselves together around the fruits,
which often — as in the case of P. argentea, cottina, reptans and
erecta — remain during the whole of the winter.
In order to lind out the extent to which P. fruticosa bears fruit,
I have examined 12 Q-specimens with 670 dusters of fruit after
a period of fine weather in August 1909, and 24 9-specimens with
799 dusters of fruit after a rainy period during the same month
in 1910. Ön the lirst occasion I obtained 66,4 % impregnated and
33,fi % non-impregnated flowers; in the latter case 50,4 %
impregnated and 49,6 % non-impregnated.
Thanks to their hairs, the fruits can be spread by means of
grazing cattle moving amongst the plants, especially in meadows
covered with knolls. Their spreading cail also take place by means
of the wind, and sometimes the water, carrying along with it fruits
that may have fallen to the ground. This holds good, above all.
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