OPHIOGLOSSUM: 



83 



K L M 



Fig. 153. Ophioglossum coriaceum. Main figure: proximal face (x 1000), 

 surface and optical section; a-d, sections through the exine ( x 2000; a, b, 

 and c are sections along the lines klin, ikno, and op in the main figure (kim 

 corresponds to the letters KLM in fig. a etc.) whereas d exhibits a part of 

 the exine with the sexine locally severed from tlie nexine (in Botrycliinm 

 simplex transitions have been seen from spores with the sexine adhering to 

 the nexine, as in the main figure above, to sucli where the sexine is almost 

 completely separated from the nexine — due to tlie chemical treatment^ 

 imparting a + pansaccate appearance to the spore); e-g, LO-patterns at 

 high, medium, and low focus. Between d and the main figure is as spore 

 seen from the side ( x 250; di, distal, pr, proximal pole). — From Erdtman in 



Svensk bot. Tidskr. 1954. 



