THE ADDER'S TONGUE FERNS. 

 r^y Elirjabeth G. Brit ton. 



AMONG the interesting and uncommon species of our native 

 ferns we must include the Ophioglossums. Their antiquity is 

 very great, since they, or some near ancestors, have been 

 found fossil in the Permian age, which is just above the 

 great Coal measures. A supposed true Ophioglossum is found in the 

 Cretaceous clays of New Jersey, and also in Greenland. Their charac- 

 ters are so simple and they have such a wide geographical distribution, 

 that they may well claim to be one of the oldest families, and to have 

 reached a highly specialized division of labor in the differentiation of 

 the fertile from the sterile froads, a separation which has been carried 

 so far in one exotic species, that they occur on different plants. We 

 have in North America north of Mexico eight species, seven of which 

 are true Ophioglossums, the eighth species belonging to the Cheiro- 

 glossa, which means hand-tongued, on account of the spreading di- 

 visions of the sterile frond; they are characterized by bearing the 

 fertile spike on very short stalks at the base of the frond, and by grow- 

 ing pendent from the trunks of trees. In our Ophioglossum palmatum, 

 there are one to sixteen fertile spikes on each frond, and they are quite 

 small as compared with the size of the frond, which is sometimes longer 

 than a herbarium sheet and often quite as broad, and is divided into 

 several sharp tapering lobes, beautifully and clearly net-veined. It has 

 been found only in Florida where it grows on palms and palmettos, 

 and ranges south into Mexico and the West Indies to Brazil. 



The true Ophioglossums have simple, undivided fronds, grow on 

 the ground, and have a single fertile spike which arises from a common 

 petiole with the sterile frond, and bears the spore cases (sporangia) in a 

 double row at the top. The largest and commonest species is Ophio- 

 glossum vidgatum^ which is known also from Europe and Asia and 

 ranges through the Atlantic states from Maine to Florida and west of 

 the Alleghanies in Kentucky and Tennessee. It is very variable in 

 size and in the time of maturing its sporangia, as well as in the shape 

 of its sterile fronds. Specimens measure from five to sixteen inches 

 in height, with the fronds from one to six inches long, and in all shapes 

 from ovate to elliptic and even linear, either obtuse or acute at the 

 apex with the base long and tapering or broad and clasping. In 

 Europe it seems to be almost as variable, though the prevailing form 

 is ovate-acute with a clasping base. Nuttall, in his Genera of North 

 American Plants., expressed the opinion that our American species was 



