4 Transactions. 



fern stems which showed the presence of abundant young plants of 

 Tmesipteris, and took them home for dissection. Between twenty and 

 thirty prothalli were discovered on this occasion in all stages of develop- 

 ment (except, of course, the very youngest), some of these prothalli 

 bearing young plants in various stages of growth. During the following 

 two months many other prothalli were obtained in the same way, the 

 total number to date being between sixty and seventy, as well as many 

 isolated prothallial plantlets, some of the latter being complete and others 

 broken in process of dissection. 



By reason of their brown colour and large size, the prothalli and the 

 rhizomes of the young plants are clearly to be seen amidst the tangle of 

 black aerial tree-fern rootlets. There is not much humus present, but 

 the rhizoids of the prothalli and plantlets are closely intermixed with 

 ramenta from the tree-fern. Prothalli and plantlets also of Lycopodium 

 Billardieri var. gracile were found in abundance on these tree-ferns, and 

 also the prothalli of various ferns and several liverworts. The spores of 

 Tmesipteris germinate best on those parts of the tree-fern stems where the 

 surface, owing to the presence of the frond-stipites, is more loose and open. 

 The young plants, once established, will develop, and their rhizomes ramify 

 in all directions, even after the bases of the fronds have completely fallen 

 away and their places have been filled up by the mat of aerial rootlets ; but 

 the younger plantlets will only be found higher up the stem. It was 

 noticed that in the groves of Dicksonia squarrosa in this particular locality 

 many young tree-ferns of from 6 ft. to 8 ft. in height bore young developing 

 plantlets of Tmesipteris, but that it was only on still taller stems that the 

 mature plants were to be seen, whilst from those of 15 ft. or more in 

 height the plants had generally disappeared altogether from the lower 

 portions of the stem and were only to be found on the upper half. It 

 would seem that Tmesipteris prefers a fairly loose substratum both for the 

 germination of its spores and also for the full development of the plants. 



That this is so becomes apparent when one observes the conditions 

 under which it flourishes on Stewart Island and on those parts of the 

 mainland {e.g., Bluff Hill) which face Stewart Island across Foveaux 

 Strait. In these localities Tmesipteris occurs very commonly in the masses 

 of loose humus which are gathered at the bases of forest-trees and tree- 

 ferns, and there the plant often reaches a most luxuriant development. 

 Also, on such large branches and tree-trunks throughout the forest as 

 are covered with humus, and especially on those which lie more or less 

 horizontal, there is frequently a rich growth of the plant. In January, 

 1915, I made a visit to Stewart Island for the purpose of searching for 

 the young plants and prothalli of Tmesipteris. This botanical district 

 is well known to be exceptionally favourable for the growth of epiphytic 

 ferns and lycopods, on account of its wet climate. There is one locality 

 especially, bordering the shore of Preservation Inlet, near the upper reaches 

 of its south-west arm, where there is a very characteristic and interesting 

 type of forest. This has been described by L. Cockayne in his Report 

 on a Botanical Survey of Stewart Island (Government Printer, Wellington, 

 1909). Cockayne speaks of this type of forest as " the Yellow-pine (Dacry- 

 dium intermedium) Association." This particular association is confined to 

 wet ground, and the low forest consists mainly of the small pine which gives 

 its name to the association, and of other conifers, as, for example, Dacry- 

 dium biforme, Podocarpus Hallii, and certain other species belonging to 

 these two genera ; while the floor of the forest is covered with curious 



