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CHAPTER ELEVEN
THE GENUS SIROCLADIUM RANDHAWA 1941
This tentative genus is established on the basis of chromato-
phores which resemble those of Mougeotia, and reproductive
structures quite similar to those of Sirogonium. The vegetative
cells are cylindric but variously curved, v^^ith plane end walls.
The chromatophores are two broad parietal plates, each with
several pyrenoids in a row, and the nucleus is supported by a
cytoplasmic pillar between the flat sides of the chromatophores.
The gametangia may become organized after an unequal division
of a vegetative cell, or from a short undivided vegetative cell.
Conjugation occurs between reflexed gametangia in adjacent fila-
ments. Adhesion is followed by the growth of a pectic ring about
the area of contact, but without the formation of tubes. The one
known species is terrestrial and has rhizoids extending into the
soil both as elongated basal cells and as outgrowths from other
cells of a filament.
Description of Species
SiRocLADiuM KUMAOENSE Raudhawa 1941. Bot. Gaz. 103, p. 196.
Vegetative cells cylindric, more or less irregularly bent, with plane
end walls, 45-64 m x 120-210 /x; chromatophores 2; parietal plates 15-20 /x
broad, each with 4 to 12 large pyrenoids arranged in a row. The nucleus
is centrally supported by a cytoplasmic pillar between the 2 chromatophores.
Conjugadon occurs between 2 geniculate gametangia without
the formation of tubes. Receptive gametangia become inflated, zygo-
spores are broadly ellipsoid, 42-70 /x x qo-io8/x; median spore wall yellow-brown
and smooth. Parthenospores and aplanospores smaller and
rounded, otherwise similar. (PI. XX, Figs. 11-14.)
India, Upper Punjab, Almora, September and October, 1939. Found
growing on moist clay on a ledge near a waterfall in the Kumaon Hills.
Specimens of this remarkable plant have been examined by the author.
The width of the chromatophores and the size of the pyrenoids are quite
unlike any specimens of Sirogonium that I have seen. That it has certain
features in common with this latter genus is unquestionable. In the specimens
seen there was no evidence of spiral twisting of the chromatophores.
It is possible that in the living material the chromatophores were even wider
than the dimensions given above.
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