Countess Dalhousie's spleenwort

Ceterach dalhousiae (Hooker) C. Christensen; Ceterachopsis dalhousiae (Hooker) Ching

Roots not proliferous. Stems erect, unbranched; scales black with brown margins, lanceolate, 2--5 × 0.6--1 mm, sparsely denticulate. Leaves monomorphic. Petiole dark to light brown throughout, dull, to 1 cm, 1/10--1/15 length of blade, indument of scales throughout. Blade narrowly elliptic to narrowly lanceolate, pinnatifid, 4--15 × 1.5--6 cm, thick, sparsely puberulent to glabrescent; base gradually tapered; apex obtuse, not rooting. Rachis light brown to tan, dull-scaly; scales brown, lanceolate. Veins free, obscure. Sori 3--7 pairs per pinna, on both basiscopic and acroscopic sides of lobes. Spores 64 per sporangium. 2 n = 72.

Moist, rocky ravines, terrestrial among and at bases of rocks; 1300--2000 m; Ariz.; n Mexico; Asia in the Himalayas.

In the flora, Asplenium dalhousiae is found only in the Mule, Huachuca, and Baboquivari mountains of southern Arizona. The pattern of disjunction in the worldwide range of this species is highly unusual.

Asplenium dalhousiae is sometimes placed in the genus Ceterach on the basis of its thick, pinnatifid leaves. Most pteridologists, however, restrict Ceterach to species with densely scaly, pinnatifid leaves. Asplenium dalhousiae is placed in Ceterachopsis by pteridologists who believe it merits its own genus.