Synonym(s): Asplenium enatum Brack.; A. enatum vat. appen-diculatum Hillebr.; A. enatum vat. caudatum Hillebr.; A. gemmiferum Schrad. vat.flexuosum sensu 0. Deg., non (Schrad.) Sim; A. gemmiferum sensu 0. Deg., non Schrad.; A. hillebrandii C. Chr.; A. kauaiense (Hillebr.) W. J. Rob.; A. kauljussii Schltdl. vat. mem-branaceum Hillebr.; A. kauljussii f. paradoxum Selling; A. /ucidum sensu A. Heller, non G. Forst.; A. mannii Hillebr.; A. mannii vat. kauaiense Hillebr.; A. obliquum sensu Brack., non G. Forst.; A. obtusatum sensu A. Heller, non G. Forst.; A. parallelum Baker; A. protensum Kaulf.; A. sectum Cope!.

Common names: kiiau

Endemic

Name honors George Friedrich Kaulfuss (1786-1830), German botanist and professor of forestry and botany at Halle, who described more than 20 new Hawaiian fern species based on Chamisso's collections (1816-1817) made during the Russian Kotzebue expedition.

Plants medium-sized, terrestrial, occasionally epiphytic or epipetric. Rhizomes decumbent, 1-4 cm diam., tips bearing many persistent stipe bases. Fronds 25-85 x 10-36 cm, usually not proliferous, a few populations with few to many proliferations on adaxial surfaces of lateral veins of several pinnae and frond tips. Stipes clustered, dark brown to black, shiny, naked except at very base where thick, wide, dark brown scales are present. Blades 1(2-)-pinnate, lanceolate, smaller at base, tips similar to lateral pinnae, shiny, bright green, glabrous; rachises green to brown. Pinnae 3-25 pairs, linear-lanceolate, sometimes deeply divided, glabrous, 2-18 x 1-2.5 cm, basal pinnae gradually reduced to 112 size of middle pinnae, margins entire to coarsely dentate, sometimes lacerate. Veins 1-forked. Sori elongate, extending from costae to margins, sometimes shorter. Indusia conspicuous.

Locally common in mesic to wet, shady forests, 150-1,200 m, all major islands except Lana 'i. Most common in the Wai 'anae Mountains of O'ahu, rare in the Ko'olau Mountains, common in sites on Kaua 'i, and much less frequent on other islands. Although the more common forms of Asplenium kaulfussii are rather uniform, the species is extremely variable in frond size and texture, presence or absence of proliferations, and number, size, shape, and marginal characters of the pinnae. Hillebrand (1888), recognizing this taxon's extreme variation, felt compelled to divide it into six species (A. bi-pinnatum, A. enatum, A. kaulfussii, A. lydgatei, A mannii, and A. meiotomum) and ten vari-eties. It is here recognized as a single, very variable species with four distinct forms. Plants show a continuum of variation between these forms. Occasionally, fronds typical of A. kaulfussii f. kaulfussii are found on plants otherwise typical of another form. Asplenium kaulfussii, a usually 1-pinnate fern, may be recognized by its glossy, prominently veined, bright green, succulent fronds with tips resembling their lateral pinnae. Many of these characteristics are diminished or absent on dry specimens.