Description from Flora of China
Archangiopteris Christ & Giesenhagen; Clementea Cavanilles; Macroglossum Copeland; Protangiopteris Hayata; Protomarattia Hayata; Psilodochea C. Presl.
Plants terrestrial (sometimes rooted in stream beds). Rhizomes erect, ascending, or creeping. Laminae 1-4-pinnate, usually evenly divided throughout, occasionally with irregular division of some segments (probably a result of stress during lamina development). Pulvini present at bases of segments, at naked nodes on stipe in juvenile fronds, generally absent at maturity, but present at maturity in some species with creeping rhizomes; primary pinnae alternate or subopposite; veins free, simple or bifurcate, false veins absent or present between veins of varying length and extending from margins toward costae; uniseriate simple hairs present, not glandular, scales peltate but generally appearing basifixed due to asymmetry. Sori borne on veins, marginal, submarginal, or medial; sporangia ± free, fused at base into receptacles, sessile, bilateral, each with 2 opposing rows of sporangia, those opening via a vertical slit on inner surface of each valve, apertures labiate, with distinct patch of specialized thick-walled cells at apex of each sporangium. Spores trilete (rarely monolete or alete), exospores granular to spinulose, spines simple or branched. 2n = 80, 160.
Species of Angiopteris differ chiefly in habit, size, and general appearance; herbarium specimens are therefore often difficult to identify, due to the lack of preserved characters.
The historical variation in species delimitation in Angiopteris has made nomenclature in this genus highly unstable. Moreover, the characters distinguishing species of Angiopteris are usually difficult to observe on herbarium specimens, which are fragmentary and usually lack information on stipule, stipe, frond size, and general habit. Therefore, many of the published names are difficult to interpret because type specimens are often small frond fragments. The majority of species listed here, therefore, may not be readily identifiable in herbaria. Most species are relatively scarce (or at least rarely collected), and it should, therefore, be noted that the majority of Chinese specimens probably belong to the following taxa: Angiopteris fokiensis, A. lygodiifolia, A. somae, and A. yunnanensis. The latter is part of the A. evecta complex, which needs further investigation. The diversity of this genus in Hainan and Yunnan is far from understood; it is possible that hybridization or allopolyploidy plays a part in the complexity of Angiopteris. Molecular work and cultivation experiments are needed to solve the complex taxonomy of this genus, but the morphological diversity is far greater than the known genetic diversity in Angiopteris. Chloroplast DNA sequence data suggest that there may be only a small number of species with highly plastic morphology. Even though perhaps not satisfactory, the list of accepted species below should be seen as an approximate consensus.
Angiopteris crassipes Wallich ex C. Presl (Suppl. Tent. Pterid. 23. 1845) and A. neglecta Ching & Chu H. Wang (Acta Phytotax. Sin. 8: 159. 1959, described from Hainan), both accepted in the FRPS account, and A. nanchuanensis Z. Y. Liu (Bull. Bot. Res., Harbin 4(3): 2. 1984), described since from Sichuan, could not be treated here because no material was seen by the present authors.
Archangiopteris subintegra Hayata (Bot. Gaz. 67: 90. 1919, described from Vietnam near the border with China) has been confused with Angiopteris subintegra Ching (here treated as a synonym of A. caudipinna). Its taxonomic status and presence within China need investigation.
About 30-40 species (but most are currently poorly defined): widely distributed in the Paleotropics, from Madagascar to the S Pacific islands; introduced and naturalized in Hawaii, Jamaica, and Central America; 28 species (17 endemic) in China.