The Botany of Iceland - 01.12.1912, Blaðsíða 186

172
H. JÓNSSON
The Fruiting Period. In the table given below is indicated
the time at which the species have been found in fruit. A + sig-
nifies that the greater part of the individuals in the samples gathered
were fruiting; a signifies that fruiting and sterile individuals
occurred in almost equal abundance, or sometimes that onljr a few
fruiting individuals occurred; a — signifies that only sterile indi-
viduafs of tlie species were found.
In the majority of the annual species the fruiting period
coincides with the vegetative stage, and thus growing vegetative
shoots and sporangia are frequently found on the same individual.
These species fruit comparatively quickly and the young, or purely
vegetative, stage is of short duration. The fruiting period extends
over spring and summer probably in the case of the majority of
the species. They do not, however, behave similarly in this respect
in the different coastal districts. Urospora Wormskioldii, Monostroma
Grevillei, M. undulatum, Ectocarpus tomentosoides and Litosiphon fili-
formis are all decidedly spring plants at Reykjavík, but in E. Ice-
land tliey liave been found bearing fruit far into the summer.
Leathesia difformis is a decidedly summer species at Reykjavík, it
has been observed fruiting in June, July, August and even into
September, but it was dying away in the iniddle of September. At
Reykjavík its life-period coincides with its fruiting-period, but in N.
Iceland it has been gathered in a sterile condition in September.
This species appears to behave in the same manner on the west
coast of Sweden (Kylin, 45) as at Reykjavík. Moreover the fact
may be emphasized that at tlie lalter place Enteromorpha Linza is
usually a summer and autumn species.
With regard to the perennial species, it happens both that the
vegetative growth and the fruit-formation is simultaneous, and also
that the two stages occur at different times. A purely vegetative,
young stage, more prolonged than in the annuals, is found in
several of the perennials; thus, I think that I have seen indications
of Alaria and Laminaria species being in a purety vegetative stage
throughout tlie tirst year and perhaps Ionger.
Kylin (45, p. 274) divides the perennial species into three groups
according to their life-activity: —
Group 1 includes species which carry on vegetative and repro-
ductive work all the year round.
Group 2. Species which carrj' on vegetative work the whole
year, but reproductive work only l'or a part of the year.