HoLLOWAY. — Studies in the New Zealand Species of Lycopoclium. 209 



characters it is primitive. The Inundata-Cernua group is generally held to 

 possess the most primitive form of prothallus, being one which is least 

 modified of all from the original self-nourishing chlorophyllous condition. 

 Nor does this belief in the primitive character of the Selago section rest 

 upon a basis of palaeontological fact, very little evidence of this kind being 

 forthcoming, but it is founded upon the broad fact that in a genus which 

 is in an exceedingly plastic condition the characters of this section show, 

 on the whole, the least degree of adaptation to external conditions. The 

 species of the Selago section are typically orthotropic in habit, and dichoto- 

 mously branched. L. Selago itself shows very little differentiation between 

 fertile and sterile regions of the stem, although in some forms the beginnings 

 of this may be seen. Seeing that the strobilar habit had been thoroughly 

 adopted by the Carboniferous Lycopodiales, it might seem natural to infer 

 that the modern members of the Selago section Avere in process of losing 

 it by reduction. However, from another point of view it would be un- 

 natural to infer this, for the type species, L. Selago, is the most widely spread 

 and highly variable of all the species of Lycopoclium, and this would certainly 

 not be the case if it occupied a position as the most recent member of a long 

 reduction series. The most natural view would seem to be that L. Selago, 

 with its congeners, has originated from a stock which did not possess the 

 strobilar habit. The stelar anatomy in this section is typically radial, a 

 type of stele which is undoubtedly as primitive as the circular protostele. 

 The prothallus of L. Selago is in a much more plastic condition tlian are 

 those of the Phlegrnaria or Clavata sections. The latter are greatly modified 

 in accordance with their respective modes of life, having practically aban- 

 iioned the chlorophyll condition, and have acquired a definite and probably 

 fixed form in relation to the saprophytic condition. The prothallus of 

 L. Selago is very variable in form according as it occurs at or beneath the 

 surface of the soil, and shows a transition stage between the chlorophyll 

 and the completely saprophytic habit. Bower indicates the significance of 

 this when he says, " A plant which shows such plasticity is clearly not far 

 removed from the self-nourishing condition of the prothallus which was 

 probably the primitive condition for them all " (3, p. 345). Lastly, the 

 L. Selago type of embryo is the simplest and least modified of all the types 

 in the genus, and may well be regarded as primitive. These, then, are the 

 evidences of primitive simplicity which point to the Selago section as com- 

 prising the most primitive members of the genus, and from this as a 

 premise the argument as to the relative position of the other sections can 

 be built up. 



A chain of forms links up the two typical forms L. Selago and L. Bil- 

 lardieri with respect to the external form of the plant and the differentia- 

 tion of the fertile region, L. varium being an important connecting-link. 

 The stelar anatomy is identical throughout the whole chain of forms, what 

 modifications there are being dependent simply upon the size of the plant 

 and occurring alike in both sections. In all the epiphytic species in which 

 it is known, whether of the Selago or of the Phlegrnaria section, the pro- 

 thallus is of the branched Phlegrnaria type. This is so in the rock-epiphyte 

 L. varium and the tree-epiphytes L. Billardieri and L. Billardieri var. 

 gracile. This form is regarded as bearing reasonable comjKirison with the 

 form which is adopted by the prothallus of L. Selago when growing well 

 below the surface. The form of the sporeling plant of the three New 

 Zealand species is identical with that of L. Selago, the first leaves being 

 large, and not scale-like, and similar to the mature foliage. The typical 



