A NOTE ON THE OCCURRENCE OF A SMUT ON SELAGINELLA CHRYSOCAULOS

Abstract

T HE material on which this note is based was collected by Professor B. Sahni at Mussoorie (India) during October I925 and was kindly placed at my disposal for investigation1. It was preserved in the field, in 4 per cent. formalin. The material was first thoroughly washed in running water (Ellis histological tank) for a full 24 hours to remove even the last traces of formalin. Then it was passed through graded series of alcohols to absolute alcohol. After this, embedding was done according to Dawson's method (1). Sections 6jt thick were cut and both double and single (safranin and iron-alum haematoxylin) stains were employed. The single stains, however, proved better than the double stains in bringing out the nuclei. The occurrence of fungi on Lycopodiales is exceedingly rare. The only case which the author has been able to find in the literature is the occurrence of a Discomycete-Acrospermum urceolatum Olson on Selaginella rupestris-described by Miss Olson(2) in I897. In the case investigated the stems and leaves (usually the latter) of the diseased plants are covered with dark brown, sometimes black, irregular patches (Figs. I, 2). An indiscriminate formation of such patches at almost any point on the plant seems quite common in Enlyloma(3,4). These dark brown patches are composed of resting spores which do not occur deep down in the tissue of the stem of the host, but in the leaf these spores do often occupy the whole thickness of the mesophyll. The spores are of varying size and shapes (oval, rectangular, triangular, ellipsoidal and circular) (Figs. 3-5). In most of the spores the walls are very much thickened, showing slight stratifications as in Entyloma ranunculi (5). The cell contents are brownish and granular with a pale translucent centre (Fig. 4 in the spore A). It is evident that the resting spores are mostly in an advanced stage of maturity. Mycelial hyphae are met with but very seldom. This is explained by the fact, that in the advanced stages Entyloma commonly produces resting spores on most parts of its mycelial hvphae (6). 1 This investigation was carried out at the Botany Department of the Lucknow University during the first term of the session 1927-1928.