The Botany of Iceland - 01.12.1928, Side 96

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JOHS. BOYE PETERSEN
Conjugatæ.
In a number of the samples, especially those from tufts of moss
round hot springs, there occurred some Desmidiaceœ. Mr. J. Nygaard
having been charged with the elaboration of this group of algæ, I have
not included them in the systematic survey of the species, but in the
list of the species I mention under the samples in question when Des-
midiaceæ occur in them. Mr. Nygaard will then make the determina-
tions and incorporate these species in the collective list of the Icelandic
Desmidiaceœ.
Zygogonium ericetorum Kútz. 0. Borge und Pascher 1913, p. 37.
E. Icel. 129 - W. Icel. 302.
The species is evidently not common in Iceland. I found some few
threads on a rocky wall in Vestdalur (129), and a larger quantity in a
dried up puddle near Geitaberg. (302).
Heterocontæ.
Botrydiopsis arhiza Borzi. Borzi 1895, p. 170, Tav. 12, 13. Pascher
Susswasserflora Heft. 11, p. 44.
N. Icel. 256 — W. Icel. 336, 338 - S. Icel. 287.
Forms yellowish-red powdery layers on rocks, earth, and woodwork.
The la^’er consists of spherical cells having a diameter of 4—34 fi. In all
the samples mentioned above the cells were lilled with drops of oil and
other nutrient substances, and were thus in the resting stage. (Borzi,
1. c. Tav. 13, fig. 12, 19). In some few cells the numerous chromatophores
could be distinguished after the addition of chlor-zinc-iodine. In a few
cells the cell contents had divided into a number of small cells (zoo-
spores?). Borzi found the species on irrorated rocks.
Evidently the species only vegetates and multiplies in damp periods,
but when it has been dry for some time, the cells may arm themselves
against desiccation by passing into the resting stage.
Botrydium granulatum (L.) Grev. Klebs 1896 p. 223. Pascher, Sflss-
wasserílora Heft. 11, 1925, p. 117, lig. 96, 1—4.
S. Icel. 387.
This species having previously been confused with Protosiphon,
(Klebs 1896, p. 169), it is difficult to gather any information from the
literature as to its geographical distribution. It can hardly be doubted
that it has a very wide distribution, yet it would seem that so far it
has only been known from temperate and warmer climates, whereas it
has not previously been found in any place having an arctic or subarc-
tic climate.
B. granulatum is habitually found on damp, clayey ground, and the
above-mentioned sample originates from a similar locality.