THE FERN BULLETIN 



17 



cause like all the species of that genus it bears its 

 sporangia in a dense layer on the backs of the fronds 

 without indusium or protection of any kind. Most of 

 the Acrostichums, however, have entire or but slightly 

 divided fronds while the present species has fronds 

 that are flabellately much divided. This fact, together 

 with its wide-creeping habit, has been assumed to be 

 sufficient reason for putting it in a separate genus, yet 

 when it fruits its entire little fronds are a very char- 

 acteristic Acrostichum feature. Our plant is also re- 

 markable for reversing ordinary fern procedure when 

 fruiting, for instead of producing its spores upon 

 fronds that are smaller than the sterile ones, as all of 

 our common ferns do, if they differ at all. it forms the 

 only broad fronds, it has for this purpose. Not infre- 

 quently, however, one may find pinnatifid fertile fronds 

 which may indicate that it is slowly progressing to- 

 ward a more distinctive form of fruiting part. 



The rootstalk is about the size of stout twine and 

 often several feet long. At intervals of an inch or two 

 it sends up a frond two or three inches high and round- 

 ish in outline, but so many times divided into linear 

 forked divisions as to present a very graceful appear- 

 ance. After it has produced from three to five sterile 

 fronds a single fertile one is developed. It does not 

 appear to be known how many times a year it fruits, 

 but it is certain that the sterile fronds outlast the fertile 

 for a considerable time for here and there one finds a 

 break in the regular arrangement of the fronds and 

 looking closer discovers the short spur that formerly 

 bore a fertile frond and from which it has finally fallen. 



There are two other species that are regarded as be- 

 longing to the genus Rhipidoptcris. All are natives of 

 the ^'est Indies or South America, beino- found in 



