Etymology Carthusiana is named after the botanist Johan Friedrich Cartheuser (1704-1777). An alternative origin is the village of Carthusium in Dauphiné, France, where Dominique Villars collected it.

Description Rhizome: short-creeping, forming an asymmetric clump, covered with old stipe bases.
Frond: 60 cm high by 15 cm wide, deciduous, monomorphic, though the sterile fronds tend to be somewhat shorter, arching, blade/stipe ratio: 2:1 to 3:1.
Stipe: grooved, base enlarged (trophopod), light brown scales at base, less above, vascular bundles: 5 in a c-shaped pattern.
Blade: 2-pinnate-pinnatifid, ovate-lanceolate, herbaceous, glabrous above, glabrous or with a few scales or glands below.
Pinnae: 12 to 14 pair, held almost horizontally, the lowest one weakly anadromic, not reduced or only slightly reduced in length compared to the second pair; pinnules first lower pinnule of basal pinna twice as long as upper one, and also larger than second lower pinnule; costae grooved above, continuous from rachis to costae; margins margins serrate, teeth spiny; veins free, forked.
Sori: round, in 1 row between midrib and margin, at the tips of veins, usually absent on the lowest pinna, indusium: reniform, gray-white, at a sinus, sporangia: dark brown, maturity: midsummer.
Dimensionality: nearly horizontal pinnae, tips pointing upward.

Culture Habitat: wet woods, moist wooded slopes, stream banks, swamps. Distribution: circumboreal, south to Pyrenees, Himalayas. Hardy to -40°C, USDA Zone 2.

Distinctive Characteristics lowest pinna: relative size of pinnules (as above) and first lower pinnule nearly opposite first upper pinnule; in the similar D. dilatata and D. expansa the first upper pinnule is distinctly closer to the rachis (anadromic).

Synonyms
Dryopteris spinulosa (O. F. Mueller) Watt.
Polypodium carthusianum Villars
Dryopteris austriaca (Jacquin) Schinz & Thellung var. spinulosa (O. F. Mueller) Fiori
Polypodium spinulosum O. F. Mueller
Polystichum spinulosum Lam. & DC.
Thelypteris spinulosa Nieuwl.