Náttúrufræðingurinn - 1985, Side 25

see Fig. 4 and Fig. 5). The germination of
P. repens started somewhat later but in
both species the maximum germination
ratio reached 80% (Fig. 5); in F. sultana it
was after two to three weeks but in P.
repens after more than a month.
In F. sultana, the formation of stato-
blasts started near the end of May, while in
P. repens statoblast formation started
some time during June 10 to July 9 (Table
1). Based on microscopic observation the
development of the statoblast was divided
into three stages: J) early stage of develop-
ment (Sl, Fig. 2A); 2) the positioning of
developing statoblast near the center of
funiculus; 3) mature statoblast (S8, Fig.
2A and Fig. 6). Although statoblast
development started later in P. repens the
time of formation was only about three
weeks (no developing statoblasts were
observed on June 10 but already 50% of
stage 3 on July 9). On the other hand the
development took at least 4-5 weeks in F.
sultana (no stage 3 statoblasts were
observed on May 30 and they had only
reached 17% on July 9). The fact that in P.
repens no stage 1 statoblasts are present in
early August (Fig. 6) while in F. sultana
they are still present in early September
demonstrates that the active period of sta-
toblast formation is much shorter in P.
repens.
The individual lifespan of F. sultana is
likely to be minimum 6 weeks, i. e. the
period from end of germination to early
July when mature statoblasts appeared.
On the other hand the lifespan of P. repens
is minimum near 3 weeks, i. e. no deveiop-
ing statoblasts on June 10 but 50% mature
statoblasts on July 9.
On the average there were 2 statoblasts
per individual in F. sultana and 5 stato-
blasts per individual in P. repens. Informa-
tion could not be obtained on the sexual
reproduction but its potential importance
for the two species is discussed. At the last
sampling date (Sept. 9) living colonies of
both species were still observed.
71