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 chromato- 

 phores. 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 yel- 

 low-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 spec- 

 imens 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. 



119 



