HoLi.owAY. — Studies in the New Zealand Sjicr/cs of Lycoijodiura. 205 



the Selago and Phlegmaria sections in this respect, for in the Selago section, 

 although roots do emerge at different points on the lower more or less 

 s])rawling adult stem, yet in the young plants they emerge at the base, and 

 throughout the life of the plants they may be seen in transverse sections 

 traversing longitudinally the cortical tissues of the stem. In the young 

 plants of L. vohihile, L. fastigiatmn, L. densum, and L. scariosum, which 

 belong to the Clavata section, there is a very marked erect stage in the 

 ontogeny. Here the prothallus is subterranean, whereas in the Inundata 

 and Cernua sections it is surface-growing, and thus necessarily the stem 

 is erect before it can even develop its foliage. However, I have often 

 observed that the naked subterranean stems on the deeply growing pro- 

 thalli of L. scariosum may be straggling and bent ; but this will probably be 

 the result merely of the presence of stones, &c., in the soil around which the 

 stem has to find its way. Thus in these plants the stem-axis emerges per- 

 pendicularly out of the soil. However, contrary to what takes place in the 

 young plant of the Inundata and Cernua sections, the stem continues to grow 

 erect. A young plantlet of L. densum found by me was no less than 4| in. 

 in height, being in every respect truly erect. Besides the first-formed root 

 there was present a second, the first " adventitious " root, which was borne 

 on the underground portion of the stem just above the " foot." The young 

 plants of L. scariosum frequently grow erect and branch to a height of 1| in. 

 to 2 in., and those of L. voluhile and L. fastigiafum to an even greater height. 

 It will thus be seen that in the Clavata section there is in the ontogeny a 

 strongly marked erect stage which precedes the adoption of the plagio- 

 tropic habit. The adventitious roots I found in no case to travel down 

 through the cortical tissues of the stem, but they emerge immediately 

 from it at right angles. Miss Wiggiesworth (31), however, records an 

 instance in a plantlet of L. complanatum. in which she found one rootlet 

 which had travelled for some distance down the cortex of the stem instead 

 of pushing its way directly to the periphery. This must certainly be 

 regarded as an abnormality. In the erect plantlets of all the New Zealand 

 species the adventitious roots commence usually to arise on the sub- 

 terranean portion of the stem just above the foot, and are also frequently 

 to be seen projecting out at right angles from the aerial region of the stem. 

 There can be no doubt that when these roots do reach the ground they 

 help the plant to bend over and adopt the trailing habit of growth. I have 

 not infrequently seen well-grown erect plantlets of L. volubile, which had 

 branched several times, on which one or more strong, naked adventitious 

 roots an inch or two in length, which had not yet reached the soil, were 

 present immediately behind the tips of the branches, the terminal portion 

 of one or other of the branches having begun to increase in stoutness in 

 anticipation of its greater extension in length. 



In the Selago section some of the species are stiffly erect, but in others 

 the lower part of the stem is somewhat recumbent. L. Selago itself shows 

 in the different forms in which it occurs in New Zealand both these habits 

 of growth. L. varium also in its smallest forms is more typically erect 

 than in the larger forms. Whatever may have been the extent of growth 

 of the ancestral stock of the modern genus, herbaceous or more tree-like, 

 the erect species that now exist do not possess the capacity of extensive 

 growth. It would seem to be more probable that the modern species have 

 sprung from an herbaceous stock than that from the whole genus the 

 character of secondary growth, whether of vascular or of cortical tissues, 

 has been completely lost without the slightest trace having been left behind. 



