13. Cyrtomium C. Presl, Tent. Pterid. 86. 1836.
Asiatic holly fern [Greek cyrtoma, arch, for the arched veins]
George Yatskievych
Plants terrestrial or on rock. Stems erect or ascending, stolons absent. Leaves monomorphic, evergreen. Petiole ± 1/2--3/4 length of blade, base not swollen; vascular bundles more than 3, arranged in arc, ± round in cross section. Blade oblong-lanceolate, 1-pinnate with pinnae not lobed, distal pinnae only slightly smaller, blade ending in basally lobed pinna ± similar to lateral pinnae, papery or somewhat leathery. Pinnae not articulate to rachis, segment margins crenate to spinulose, sometimes also coarsely dentate; proximal pinnae not reduced, petiolulate, equilateral or somewhat inequilateral with acroscopic base more developed; costae adaxially grooved, grooves continuous from rachis to costae; indument of filiform scales abaxially, absent adaxially. Veins elaborately anastomosing, areoles formed with 1--3 included veinlets. Sori in 2 or more rows between midrib and margin, round. Indusia peltate, persistent or caducous. Spores brown, with inflated folds or wings. x = 41.
Species ca. 15 (2 in the flora): North America, Asia, Africa including Madagascar, Pacific Islands in Hawaii.
This difficult genus requires further systematic study. Estimates of species numbers have ranged from 9 (C. Christensen 1930) to 59 (Shing K. H. 1965). The group might better be considered a subgenus of Polystichum , from which it is poorly differentiated morphologically.
SELECTED REFERENCES
Christensen, C. 1930. The genus Cyrtomium. Amer. Fern J. 20: 41--52. Ching, R. C. 1936. On the genus Cyrtomium Presl. Bull. Chin. Bot. Soc. 2: 85--106. Shing, K. H. 1965. A taxonomical study of the genus Cyrtomium Presl. Acta Phytotax. Sin., Addit. 1: 1--48.
