A NEW JAPANESE ACROSTICHUM. (l I l) 



in its lower part, large and ovate like those of the stipe, but become, in its up- 

 per part, gradually smaller and narrower, and finally disappear. The frond 

 becomes rather abruptly thin at the margin which is recurved and diaphanous. 

 The young and small fronds are, unlike the mature ones, spathulate with a 

 rounded apex and a very narrow tapering base. The fertile fronds are similar 

 to the sterile except in their longer stipe, smaller size, lanceolate form, and 

 closer veins. The sori which densely cover the under surface of the frond 

 continue even to its decurrent base. The section of the fertile frond shows 

 that the sporangia arise at any place on the under surface, and the cells of the 

 parenchyma are smaller towards that surface. The sporangia are dark-brown, 

 round and compressed, and about 0.31 mm. in diameter; the number of the 

 segments of the incomplete annulus is 1 3 to 15; the stalk consists of three rows 

 of cells, and is about 0.5 mm. long. The spores are subovoid or subreniform, 

 and with a brown and irregularly wrinkled exospore; they are 0.046 to 0.065 

 mm. long and 0.028 to 0.04 mm. broad. 



Dr. W. J. Hooker in his Species Filicum {vide vol. v., p. 198.) unites in 

 Acrostichuia conforme, Swartz, a number of distinct species of other writers 

 and of his own, such as A. angulatum and A. gorgoneum of Blume, A, glafidu- 

 losum and Vittaria acrostichoides of Hooker and Greville, &c., which are more 

 or less distinct from each other. My plant may be included in this variable 

 species. But as Dr. Hooker's description of the species does not agree with 

 my plant, I have ventured to make it a distinct species. The plant described 

 some time ago by Messrs. E. Yoshinaga and S. Okubo as a species of Aero- 

 stichum in this magazine {vide vol. ii, p. 138, t. 10.), is the same as my plant. 



