Art. XXXIX.—Notes on Ferns.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 37, 1904, Page 377

Art. XXXIX.—Notes on Ferns. By H. C. Field. [Read before the Wellington Philosophical Society, 1st June, 1904.] In previous papers I have mentioned peculiar forms of our New Zealand ferns, of which examples had been sent to me by persons who had experienced difficulty in identifying them; and I now note the following:— Towards the end of last year a Miss Allen sent me a pressed frond of a fern which she had gathered in the bush between Rotorua and Tauranga. It was unmistakably a barren frond of Lomaria vulcanica and only differed from the normal type in being of a bright yellowish-green instead of the usual dark-olive. Her brother, however, has since sent me other specimens, which explain why there had been difficulty in classifying the plant. Lomaria vulcanica is usually a tufted fern, producing a crown of fronds, and this is sometimes raised 2 in. or 3 in. above the ground on a short caudex. Old plants often produce external crowns, and spread in this way over a space of 1 ft., or nearly so, in diameter. The form, however, which Miss Allen found has widely spreading creeping rhizomes, about 1/8 in. in diameter, dark-brown in colour, and slightly scaly, from which the fronds grow at intervals of several inches. It is evident that this fern, like several others of our New Zealand ones, occurs in two forms, and I think it would be well to distinguish this creeping variety as “repens.” Miss Allen afterwards sent me, from the Piako Swamp, some fronds of what she supposed to be the Nephrodium thelypteris, but which proved to be Nephrodium unitum. This latter fern

is also a tufted plant, usually growing in volcanic soil in the immediate vicinity of hot springs, and used to be particularly abundant along the banks of the hot stream which flowed from Rotomahana into Lake Tarawera, from whence I brought a couple of plants a few weeks before the eruption, and had them growing in my greenhouse for about nine years. Mr. Allen has since sent me a couple of plants from the Piako Swamp, which present very peculiar features. Instead of the fronds being produced from a crown in the ordinary manner, they grow from a sort of underground caudex about 18 in. long. It is evident that when the plants first grew the surface of the swamp was fully 18 in. below its present level, and that as it has risen, by reason of the growth and decay of the Sphagnum moss, the fern has been compelled to raise its crown higher and higher, so as to avoid being smothered, and reach the daylight. In this way the underground caudex has been formed; but it is evident that this caudex is an elongation of the actual crown, since, instead of the fronds being produced on the top in the ordinary way, they grow out of the sides of the caudex, a foot or more below the surface, and have struggled up through the moss with such difficulty that the actual fronds are very small, and situated at the ends of an extremely long stalk. The plants are evidently very old ones, and as they rose by reason of the greater elevation of the surface of the swamp, the caudices have become forked, in one case into two and in the other into three branches. I have potted the plants in leaf-mould, in order to see whether, under cultivation, they will revert to the ordinary type. Mr. Allen also sent me a curious specimen from the bank of the Piako Swamp. It has a long stipes, and the frond is branched and slightly crested. The pinnæ form parallelograms with two obtuse and two acute angles, and are connected with the rachis, at one of the latter angles, by a short stalk. The edges of the pinnæ are indented into short rounded or obtusely pointed lobes. Altogether the specimen at first sight looks like a curious harsh form of Adiantum. On closer inspection, however, its brown channelled stipes, furnished with scattered scales, shows it not to be an Adiantum, but an abnormal form of Aspdium richardii, one of our commonest New Zealand ferns. It is well that fern-collectors should know of these peculiar forms of our ferns, so as to be able to classify their specimens more easily, and therefore I send you these notes.