210 Transactions. 



epiphytes are for the most part pendulous, although some, by reason of the 

 strongly thickened cortex, are more rigid. L. Billardieri sometimes grows 

 on the ground, and is then more or less erect, with shortened overhanging 

 strobili. L. varium also provides a striking gradation in form from the 

 stiffly erect to the pendulous habit. The entire genus is characterized by 

 the fact that the roots are adventitious and arise behind the growing apex. 

 In the sections Selago and Phlegmaria, in accordance with the habit of 

 growth, the roots emerge at the base of the stem, penetrating down the 

 cortical tissues in order to do this. In L. Selago the characteristic ortho- 

 tropism is modified by the somewhat sprawling character of the lower region 

 of the stem, and the roots emerge from the stem throughout this region. 

 In L. varium and L. Billardieri the stem is more vertical, whether erect or 

 pendulous, and the roots are borne only in a bunch at the base. The 

 transition between the Selago and Phlegmaria conditions of the fertile region 

 is strikingly exemplified in L. varium and L. Billardieri var. gracile, which 

 may on the one plant show practically all stages between a wholly undif- 

 ferentiated condition of the fertile region and a special sporophyll and 

 special strobilar formation. At the base of mature xerophytic plants of 

 L. Selago the leaves are of the larger form which is characteristic of the 

 mesophytic variety, and in the embryo plant the first leaves are large and 

 not scale-like. This would seem to indicate that the immediate ancestors 

 of the species of the Selago type possessed leaves which were larger than 

 the acicular or scale-like leaves of the common Lycopodiaceous form. The 

 three New Zealand species which belong to the Phleg?naria section, as also 

 many others, all possess the larger form of leaves. The fact that not a 

 few epiphytic species have the acicular form of leaf may indicate that the 

 large leaf is not merely a mesophytic character, but is an indication of the 

 presence of more than one line of evolution in the Phlegmaria section. It 

 is, of course, probable that the epiphytic habit has been adopted by species 

 which are not immediately related, but that there have been parallel cases 

 of adaptation to similar conditions, and it is possible that these species 

 may have sprung not only from members of the modern Selago cycle of 

 affinity other than L. Selago itself, but even from related forms now wiped 

 out. However, in the New Zealand species we can trace a continuous chain 

 from L. Selago to L. Billardieri through L. varium. Thus a comparison of 

 the New Zealand members of the Phlegmaria section with L. Selago brings 

 forward facts which are in close accord with the belief that the epiphytic 

 species have all been derived from the Selago cycle of affinity, and that 

 the evolution of the characteristic Phlegmaria plant-form, strobilus, and 

 prothallus has been determined by the epiphytic habit. Moreover, the close 

 similarity between the two sections in respect to their chief characters may 

 be regarded as sufficient ground to justify the grouping of these two sections 

 as one natural division of the genus. 



When we turn to those species which are classified in the Clavata section 

 we find that the main characters of both gametophyte and sporophyte are in 

 a less variable condition than are those of the Selago and Phlegmaria sections. 

 They have become more fixed in form and structure, and are all obviously 

 in direct harmony with the mode of life. The individual species do not, 

 on the whole, show such a wide range of variability in the external form of 

 the sporophyte or in the nature of the fertile region as do, for example, the 

 species L. Selago, L. varium, and L. Billardieri, although certain charac- 

 teristic " fixed " features are to be found in almost every species. How- 

 ever, in the life-history there is to be found striking evidence of the fact 



