Synonym(s): Polypodium abietinum D. C. Eaton; P. tamariscinum Kaulf. var. abietinum (D. C. Eaton) Hillebr.

English: elegant kihifern

Endemic

Latin abies, fir, + -inus, pertaining to, in reference to the living plant that sometimes suggests a minute fir tree. Plants epiphytic, delicate. Rhizomes short-creeping, scaly, 3-4 mm diam. (including scales). Fronds clustered, erect, small, (2-) 4-8(-13) cm long. Stipes thin, 1/4-1/6 frond length, less than 0.5 mm diam., narrowly or minimally winged. Blades 2-pinnate (occasionally with acroscopic basal segment again pinnatifid), ovate to lanceolate, with dark reddish brown, red, or yellow glands; rachises narrowly winged. Pinnae often much smaller near frond bases. Ultimate segments radiating from plane of blade (seen best on living plants), diminutive, spatulate to linear, 1-3 x 0.1-0.3 mm, tips rounded to acute. Sori abaxial, usually wider than ultimate segments.

Occasional or locally common epiphyte in wet forests, 510-1,310 m, Kaua'i, O'ahu (Ko'olau Range), Lana'i (single collection), and East and West Maui. In the Ko'olau Range of O'ahu it exhibits a strong preference for 'ohi'a hii (Syzygium sandwicensis) as a host tree, although it is occasionally found on other trees.

Adenophorus abietinus appears related to A. tamariscinus but is clearly distinct, and no hybrids have been found where they grow together.

Adenophorus abietinus is the smallest, most delicate fern of the genus and may be distinguished from A. tamariscinus by its smaller fronds, thin stipes, diminutive pinnules that tend to spread at right angles to the plane of the fronds (a three-dimensional quality best seen on living plants), and sori wider than the pinnules.