In the year 1810 there appeared in Robert Brown's Prodromus Floræ Novæ Hollandiæ et Insulæ Van Diemen, p. 160, a brief description of a rare Australian Fern to which the generic name Platyzoma was given. The habit of stem and leaf, and in general the form and position of the sporangia, led Brown to the conclusion that Platyzoma was of Gleicheniaceous affinity. It was noted that the plant was heterophyllic; for not only did it possess pinnate leaves suggestive of those of certain Gleichenioid forms, but also small, compressed, and filiform leaves devoid of pinnæ. To the form of the larger and pinnate leaves Brown paid particular attention, noting chiefly that the leaves of Platyzoma were unbranched, whereas a branched condition was typical of the leaves of Gleichenias. This unbranched condition of the leaf seemed to Brown a sufficiently distinctive feature to justify the foundation of a new Gleicheniaceous genus —the monotypic genus Platyzoma; and he named the single species Platyzoma microphyllum.