466 Benedict : The genus Ceratopteris 



containing chlorophyl, the annulus longitudinal, few-celled (4-10), 

 and causing irregular dehiscence, or many-celled (20—70), and with 

 8-10 lip-cells and consequent regular dehiscence. Spores 16 or 

 32 per sporangium, ephemeral, triplanate, the inner faces smooth, the 

 dorsal (outer) face rounded and regularly marked with three series 

 of anastomosing ridges. 



Some of the characters noted are decidedly unusual. The 



bracing of the plant by means of the elbowed stipes is peculiar, 



and the place of origin of the roots is even more anomalous. 



Attention has already been called to these facts by Miss Sibille 



Ford in connection with a study of the vascular anatomy of Cera- 



Within 



topteris '' thalictroide$r ^ The bent stipe seems to be a feature 

 present only In the plants which grow rooted in the soil. In the 

 floating plants the stipes are swollen and bulbous, but not bent. 

 Goebel f has noted in the field that one species, probably C. pieri- 

 doides^ may assume either the floating or the anchored habit, and 

 this statement is borne out by the herbarium material of this spe- 

 cies examined, but is true for this species only, as all the other 

 forms seem to be adapted at maturity to a fixed habit only. 



The genus was described in 182 1 by Brongniart, based on the 

 Linnaean species Acrosticlmm siliquostim and A. thalictroides, 



seven years six other names had been proposed for the 

 same genus, two of which, however, were not properly published 

 but were merely cited as synonyms. In addition to these, the 

 synonymy contains, besides the already mentioned Acfostichnm, 

 Pteris Swartz and others, Belvisia Mirbel, Onychhun Hasskarl, and 

 Naias Blanco. | 



As may be seen, many different views have been held as to the 

 natural position of this genus. Brongniart, who distinguished five 

 famines of ferns, viz,, Ophioglossaceae, Osmundaceae, Marat- 

 tiaceae, Polypodiaceae, and Gleicheniaceae, placed Ceratopteris 

 with the last because he considered its annulus to be transverse. 

 But he clearly misinterpreted the facts, since the annulus, although 

 sometimes rather crooked, is undoubtedly longitudinal, and its 

 structure resembles that of the Polypodiaceae, from which it 

 differs principally In the size, shape, and number of the component 



♦Ann. Bot. 16: 95-121. pL i. 1902, 

 t Pflanzenbiol. Schild. 2: 281. 1893. 

 % Citations are given under the head of Synonymy, 



