Male fern Leaves monomorphic, 15–100 cm long, petiole up to 1/3 length of blade. Leaf blade narrowly elliptic, green, twice pinnate at the base, not glandular. Pinnules downward- and upward-pointing ones ca. equal. Indusium lacking glands (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
The broadly horseshoe-shaped indusium identifies its members as
Dryopteris.
The length ratio of downward- to opposing upward-pointing pinnules on the lowest pinnae separates Spinulose, Spreading, and Male ferns (Giblin et al.[eds] 2018; Lesica et al. 2012):
Male Fern -
Dryopteris filix-mas, native:
* Leaves are 1- to 2- pinnate at the base and deciduous.
* Petiole is about one-third or less the length of the blade.
* Leaves are narrowly elliptic or lance-shaped in outline.
* Downward- and upward- pointing pinnules are about equal in length and width.
Spreading Woodfern -
Dryopteris expansa, native:
* Leaves 2- or 3-pinnate at base and can be more evergreen.
* Petiole is often about half as long as the blade.
* Leaves are broadly ovate to triangular in outline.
* Leaf blade is about one-half to two-thirds as wide as long (except in very robust plants).
* The first downward-pointing pinnule on the lowest pinnae is at least twice as long and wide as the opposing upward-pointing pinnule.
* Teeth on pinna margins toothed with a spine tip less than 0.03 mm.
Crested Shieldfern -
Dryopteris cristata, native, SOC:
* Leaves are 1-pinnate and of two types: erect fertile fronds are taller than the sterile arching, evergreen fronds.
* Petiole is less than half as long as the blade.
* Leaves are narrowly lance-shaped in outline.
* Pinnae are deeply pinnately lobed.
Spinulose Shieldfern -
Dryopteris carthusiana, native:
* Leaves 2- or 3-pinnate at base and deciduous.
* Petiole is often shorter than the blade.
* Leaves are broadly ovate to triangular in outline.
* Leaf bladed about one-half to two-thirds as wide as long (except in very robust plants).
* The first downward-pointing pinnule on the lowest pinnae is less than twice as long and wide as the opposing upward-pointing pinnule.
* Teeth on pinna margins with a prominent spine tip about 0.05 mm long.
* Leaves deciduous.
Mesic forests and in moist to wet rock crevices, often along streams and beneath tall shrubs; montane to subalpine (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
