118 



of its range, but it appears to occupy a zone much higher than 

 the other estuarine plants. 



Isoetes riparia Engelm. Plants of Isoetes (nos. 6108, 6437), 

 which clearly belong to the /. saccharata-I. riparia complex, 

 were found sparingly in the tidal mud on both visits. A rather 

 poor specimen of the earlier collection (no. 6108) was submitted 



Plantago cordata 



to the late T. Chalkley Palmer who said that its identity could 

 not be certain, but that it was almost certainly not /. Eatoni 

 which it resembled in spore characters, and that he could not 

 call it /. saccharata, and that similar semiabortive spores (meas- 

 uring 376-423ju) were found in young or spindly /. riparia. The 

 plants (no. 6437) were of moderate size (leaves 10-15 cm. long) 

 with strongly bilobed dark corms, and megasporangia in which 

 the spores averaged 400jii in diameter. The markings consisted 

 of close-set high jagged crests, which appeared identical with 



