Flora of the Hawaiian Islands
Pteridophyte Literature for Asplenium caudatum
Brown & Brown, 1931; Copeland, 1932; Palmer, 2003; Brownsey, 1998; Lorence & Wagner, 2019.
   Aspleniaceae -- The Spleenwort Family Bibliography
      Asplenium caudatum
General Information
DistributionSE Asia to Polynesia, but not New Zealand.In the Hawaiian Islands, indigenous to Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Hawai`i.

Click here for detailed USGS map by Jonathan Price
Elevation200-1000 m
Epiphytic or terrestrial. Rhizomes stout, creeping or suberect, 1-1.5 cm in diameter with 7-30 fronds clustered distally, apex clothed with brown, clathrate, narrowly oblong or subulate scales 4-7(-15) mm long, 0.5-1 mm wide with entire margin.
Fronds with stipe (5–)28–40 cm long, 3–10 mm in diameter, dull dark brown, usually densely covered with reddish brown to black, narrowly ovate-triangular to linear scales 4–10 mm long with subentire margin, mixed with smaller hairlike and irregularly branched appressed scales, occasionally glabrate with few to no scales; blade (10–)41–150 cm long, (4–)12–35 cm wide, narrowly oblong to linear-lanceolate, stiffly chartaceous or subcoriaceous, 1-pinnate-pinnatifid to 1-pinnate-pinnatisect, pinnae gradually reduced toward blade base, several basal pinnae sometimes reduced to 1/3 or less size of middle pinnae, narrowing gradually to non-proliferous pinnatifid apex, rachis usually covered with narrowly ovate-triangular scales with long filiform apex and spreading basal cilia similar to those on stipe; pinnae (9–)20–50 on each side, alternate, middle pinnae subsessile or on stalks 1–2 mm long, (2–)4–17 cm long, (0.6–)1–2.5 cm wide, oblong- to linear-lanceolate, deeply lobed to nearly pinnatisect, divided ½–¾ width, lobes diverging at 20–45 degree angle from costae, acroscopic basal lobe largest, segments acute to obtuse at apex, shallowly dentate, base narrowly cuneate, apex long and tapering, costae and veins of both surfaces scattered with fine light brown to black, curling hairlike scales with a pair of long curved basal cilia, usually glabrescent above; veins at acute angle to costae, forking 2–3 times, ending in teeth near margin.
Sori in (1-)2 parallel rows along costae, alternate, 5–10 mm long, each pinna lobe also usually with 1–3 shorter sori 1.5–3 mm long facing each other; indusium brown with thin margin.
Asplenium horridum Kaulf. var. humile E. D. Br. seems to be a depauperate but fertile form of A. caudatum, as there are intermediate forms linking it with typical full-sized plants.
David Lorence