392 A. W. JEvans — Hawaiian Hepaticoe, of the Tribe Juhuloideoe. 



leaf turned away from the apex ; the fourth, a second underleaf, and 

 so on. 



The Lejeuneese are pale or bright green in color and are some- 

 times tinged with brown or black, but never with red. The leaf- 

 lobes vary from orbicular to lanceolate in shape, and their margins 

 show all gradations from entire to laciniate-dentate. With rare 

 exceptions, the lobule is attached to the lobe by a broad fold and to 

 the axis by a long, almost longitudinal line of insertion. The lobule 

 is strongly conv^ex when seen from the postical surface, and its free 

 margin is either involute or appressed to the stem, so as to form with 

 the lobe a fairly tight water-sac. In moist situations this becomes 

 unnecessary, and the lobule is usually more or less reduced, some- 

 times so much so as to be hardly distinguishable. Underleaves, 

 when present, are sometimes undivided and sometimes bifid. 



A branch in the Lejeuneeae springs from the basiscopic part of the 

 postical half of a segment,* and the lobule of the corresponding leaf 

 is normally developed. The branch remains close to this leaf and is 

 apparently borne just behind it.f Corresponding with this method 

 of branching, the first leaf of a branch is an underleaf; the second, 

 a side-leaf turned away from the apex of the main axis ; the third, 

 a side-leaf turned toward the apex, and so on. According to Leit- 

 geb, the first three leaves of a branch do not appear as such, but 

 remain united as a sheath, enclosing the apical region of the branch, 

 which may or may not develop fai'ther. 



A peculiar type of branch is the " innovation," which is found in 

 nearly every genus of the Lejeuneefe. These innovations are borne 

 just behind one or both of the perichaetial bracts, which are here 

 reduced to a single pair. Sometimes an innovation is small and 

 simple, but it is more frequently as large as the axis bearing it, 

 whose own growth has been stopped by the formation of the arche- 

 gonium. In such a case, the innovation itself, while still short, 

 often gives rise to a second flower and a new innovation. This 

 mode of growth is sometimes repeated several times, the result 

 being a complicated and characteristic flower-cluster. In case an 

 innovation is developed behind only one of the bracts, it is not 

 unusual to have the bracts and perianth pushed to one side, where 

 they seem to assume a lateral position, the innovation apparently 



* An exception is found in the genus Stictolejeunea, where the branches are 

 home as in the Frullaniece. Cf . Spruce, Hep. Aniaz. et And. 307. 



f This type of branching is found also in the genera Radula and Scapania. 

 Cf. Leitgeb, Unters. iiber die Leberm. ii, 29. 



