The Morphology and Taxonomy of Angiopteris (Marattiaceae) with Description of a New Species

Abstract

Summary. The morphology and anatomy of plants of the genus Angiopteris are discussed, with reference to descriptions and illustrations of two species in cultivation at Kew, and to the problem of finding characters by which species in this genus may be distinguished from each other. A new species from New Guinea, A. canaliculata, is described and illustrated. The first (and still the most comprehensive) account of the morphology and anatomy of a living plant of Angiopteris was by Harting in 1853, as part of a joint work with de Vriese who dealt with the taxonomy of species in the genus, based on herbarium specimens. De Vriese described in all 6o species, 41 of which were new. So it was the work of de Vriese & Harting that I first consulted as an aid to understanding two mature plants now in cultivation at Kew, one of which I had sent from Sarawak in 1958 and the other from New Guinea in 1963. I had also at my disposal a considerable series of dried specimens (some named by de Vriese) from many sources, also descriptions of species published after 1853. In Synopsis Filicum (Hooker & Baker, I868) all 6o species of de Vriese were reduced to one (A. evecta) and no more were described until 1898, but they have multiplied considerably in the present century. Hieronymus (1919) appears to be the only author who has published a discussion on the characters which may be used to distinguish species; he worked mainly with dried material but noted that recurrent striae could be better seen when specimens have been soaked in water. After studying the living plants in comparison with the literature, I found that the Sarawak plant corresponded with the description of Angiopteris elliptica v.A.v.R. from southern Sumatra and verified this by examining the type material in the British Museum (Natural History), but I could not certainly identify the New Guinea plant with any published description. I concluded that some specific characters cited in descriptions were distorted in the process of drying, and that more different and more reliable characters needed to be found in order that species may be clearly distinguished. It was obvious that living plants are observable with more precision, and offer a wider range of characters, than dried specimens. I looked at my two plants in search for possible characters, noting the considerable differences between the two and also comparing them with younger plants of other species now in the fern houses at Kew. My examination of the plants was much helped by the careful observations of Mrs. J. A. Lowe who prepared the accompanying illustrations. A feature of the living plants which strikes the eye is the presence of short vertically elongate paler areas scattered all over the surface of petioles; the outlines of these areas are more distinct in some plants than in others, and are very sharply defined in my Sarawak plant though on dried specimens made from it they are hardly detectable. In the middle of each of these pale streaks is a dark round or elliptical spot; sometimes the spot is white in the middle