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involucre and perianth becomes pushed to one side by the apparent innovation 

 and then shows its true morphological character as a short branch. A careful 

 study of the conditions found in 7^. Rappii, as well as in most of the other North 

 American species of Trachycolea, shows that Stephani's ideas cannot be main- 

 tained. There are cases, for example, such as the one shown in figure 2, where 

 the female axis bears no branches in the vicinity of the inflorescence excepc the 

 antheridial spikes. Under these circumstances it would hardly be possible to 

 interpret the portion of the axis bearing the involucre and perianth as a branch 

 of the part below it. But even when the female axis bears what Stephani calls 

 an apparent innovation, as shown in figure i, this always arises in connection 

 with an elobulate leaf of the axis and clearly represents the missing lobule of 

 this leaf, just as in all ordinary branches throughout the genus Frullania. The 

 presence of the elobulate leaf shows, therefore, that the apparent innovation 

 represents a true branch and ought not to be regarded as the direct continuation 

 of the axis. When the involucre and perianth become pushed to one side through 

 the robust development of this branch, the axis formed is a sympodium and not a 

 monopodium as Stephani's explanation would imply. It thus seems to be clear 

 that while the female inflorescence is sometimes borne on a short branch, it may 

 in other cases be borne on a leading branch, as previous writers have maintained. 

 Its position, in fact, seems to be constant for a given species and occasionally 

 affords helpful characters in distinguishing between closely related plants. 



The cell structure of F. Rappii presents a number of interesting peculiarities 

 with respect to the distribution of the local thickenings in the walls. In the 

 lobes of the leaves, trigones are everywhere apparent and frequently bulge out 

 into the cell cavities (fig. 5). Intermediate thickenings, on the other hand, are 

 rare and many lobes fail to show them altogether. Even on the bracts, the 

 lobes show very few thickenings of this character. The cells of the lobules of 

 the ordinary leaves differ widely from those of the lobes, intermediate thicken- 

 ings forming a conspicuous feature of their walls (fig. 6). On the bracts the 

 lobules are still well provided with these thickenings, although there are fewer 

 than on the ordinary leaves. The cells of the underleaves, bracteoles, and peri- 

 anths are much like those of the lobules of the bracts. In most of the species of 

 Trachycolea which have been heretofore described, the thickenings of the walls 

 are fairly uniform throughout all the appendicular organs. In the usual type 

 of cell, represented by such species as F. ehoracensis and F. sqiiarrosa, both 

 trigones and intermediate thickenings are present in practically all the cells, 

 thus making the contours of the cavities wavy. In the rarer type of cell, 

 represented by F. inflata Gottsche, F. Bolanderi Aust., and their allies, no inter- 

 mediate thickenings whatever are present, the local thickenings being restricted 

 to the trigones. In these cells the cavities are polygonal in outline with rounded 

 angles. It will be seen at once that the cell structure in F. Rappii is inter- 

 mediate between these two types. 



In comparing F. Rappii with other species of Trachycolea the Cuban F. coh- 

 rensis Gottsche^ will be found to be one of its closest allies. This species was 



1 In Stepiiani, Hedwigia 33: 142. 1894. 



