Evans: Notes on genus Herberta 195 



to either leaves or underleaves. It is of course possible that their 

 aberrant position is due to secondary displacements caused by in- 

 equalities of growth, but this could not be definitely determined 

 from the material studied. The secondary stems are sometimes 

 direct extensions of the creeping rhizomes, but it is usually possible 

 to demonstrate their origin as branches. Even under these 

 circumstances they usually bear small leaves at the base and 

 only gradually give rise to the normal leaves. Sometimes the 

 change is more abrupt, and all gradations may be present between 

 the small-leaved prostrate rhizomes and the typical secondary 

 stems with large leaves. 



The secondary stems differ greatly in length in different species 

 and even in the same species under varying conditions. In some 

 of the robust tropical species a length of 25 cm. may be attained. 

 The stems are usually ascending but are often pendulous and 

 sometimes form conspicuous festoons hanging from the branches 

 of trees. The branches are always intercalary, just as in the case 

 of the rhizomes. The normal vegetative branches take their 

 origin in the axils of underleaves and are rarely subdivided. In 

 most cases they spread widely and show a flagelliform appearance, 

 their leaves being distinctly smaller than those of the stem. 

 When the growing point of a stem is injured, however, a ventral 

 branch sometimes changes its direction of growth and assumes 

 that of the stem, its leaves at the same time increasing in size. 

 The same thing is true of the subfioral innovations, which may be 

 either ventral or lateral in position. The growth of the stem is 

 here brought to an end by the development of the archegonia. 

 Rhizoids are often absent altogether from the secondary stems. 

 When they occur they are usually restricted to the underleaves 

 and leaves of the ventral branches, although the normal leaves 

 and underleaves have the power of developing them. 



The leaves (Text figs, i, 14, 15, 21-25) and underleaves of 

 the secondary stems present a great deal of uniformity throughout 

 the genus. They are more or less deeply bifid with a narrow sinus 

 and sharp divisions. In rare cases a leaf may be trifid instead of 

 bifid, a peculiarity to which certain species seem to be more subject 

 than others. The divisions are sometimes distinctly grooved but 

 show little tendency to be complicate, both lying approximately in 



