Abstract
Tmesipteris Vieillardi , Dangeard, is one of those rare plants from the Pacific region, of which our knowledge has remained comparatively incomplete, owing chiefly to the difficulty of obtaining adequate material. As is well known, the genus Tmesipteris occurs under several forms, which Dangeard described as so many distinct species, but which are generally grouped under the name Tm. tannensis , Bernh. The usual habit of plants belonging to this genus is that of semi-erect or pendulous epiphytes, although specimens are frequently seen growing on the ground. But it is not commonly known that one of the forms is normally erect and terrestrial, only rarely growing as an epiphyte. In its external morphology and anatomy also Tm. Vieillardi shows some noteworthy points of difference from the remaining forms ( see Plate 5, figs. 1, 5, 8 and 10), and it is not unlikely that it represents the parent type from which the other forms may have arisen. The chief object of the present paper is to describe these distinctive features of Tm. Vieillardi and to discuss their bearing upon the affinities of this plant, both within the family Psilotacese and with other Pteridophytes. Advantage has been taken of this opportunity to publish photographs of the different “forms” of the genus, so as clearly to illustrate, for what they are worth, the individual differences in habit and external morphology.

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