394 



BOTANICAL GAZETTE 



[NOVEMBER 



sowing of the spores and the appearance above ground of the 

 first tiny leaf of the sporeling. We have seen one sporeling with a 

 fertile spike bearing a few sporangia while still attached to the 

 pro thallium, but it is probable that ten or twelve years usually 

 elapse between the germination of the spore and the development 

 of a plant up to the spore-bearing stage. During the past twenty 

 years we have made so many unsuccessful attempts to germinate 

 Botrychium that we did not even try to test our theory by this 

 method, but collected some circumstantial evidence which supports 

 our conclusion that B. dissedum is a mutant from B. obliquum. 

 Before presenting the evidence it is worth while to call attention 

 to the distinguishing characters of the two forms. 



B. obliquum and its varieties have oblique leaflets with margins 

 ranging from nearly entire to quite sharply serrate, sometimes 



doubly serrate, while B. dissedum has 

 a leaflet, still oblique in topography, 

 but so dissected that the specific name 

 is very appropriate (figs. 3-5). This 

 difference in leaves is recognizable even 

 in the sporeling (figs. 6 and 7). The 

 leaves of sporelings are simpler in out- 

 line than those of larger plants, but the 

 general character of the margins is char- 

 acteristic from the first, so that there 

 is no danger of confusing the forms. 



In B. obliquum and its varieties 

 there is considerable variation in the 

 shape of the leaflet and in the character of the margin; but, so 

 far as the margin is concerned, the differences are confined to a 

 greater or lesser degree of serration. The deepest serration of 

 B. obliquum would not be mistaken for the deeply cut margins of 

 B. dissedum. In B. dissedum there is also some variation in the 

 margins, but the dissected character is always evident, the differ- 

 ences being in the extent of the dissection (fig. 8). 



We are familiar, of course, with the great variations in the 

 leaflets of cultivated ferns, where a single leaf may have leaflets with 

 a nearly entire margin, leaflets deeply cut, and still others so 



Figs. 6, 7. — Sporeling of B. 

 obliquum; natural size; spore- 

 ling of B. dissedum; natural size. 



