Athyrium distentifolium var. americanum

(Butters) Boivin

Naturaliste Canad. 93: 272. 1966..

Common names: American alpine lady fern athyrie alpestre sous-espèce américaine
Synonyms: Athyrium alpestre var. americanum Butters Athyrium americanum (Butters) Maxon Athyrium americanum subsp. americanum (Butters) Lellinger Athyrium alpestre var. gaspense Fernald Athyrium distentifolium subsp. americanum (Butters) Hultén
Treatment appears in FNA Volume 2.

Stems ascending or short-creeping. Petiole straw-colored or redbrown distally, (7–) 10–30 cm, base dark redbrown to black with 2 rows of teeth, swollen; scales at base brown to dark-brown, lanceolate or broadly lanceolate, 13 × 3 (–5) mm. Blade narrowly elliptic or lanceolate, 2–3-pinnate-pinnatifid, 15–55 (–65) × 3–25 cm, moderately narrowed proximally, broadest below middle, apex acuminate. Pinnae short-stalked, narrowly deltate to deltate-oblong, apex acute. Pinnules deeply pinnatifid, segments oblong, crenulate. Rachis, costae, and costules with small, pale-brown scales. Veins pinnate. Sori round to elliptic; indusia absent or very minute, scalelike. 2n = 80.


Habitat: Wet talus slopes, rocky hillsides, alpine meadows
Elevation: 600–3100 m

Distribution

V2 500-distribution-map.gif

Greenland, Alta., B.C., Nfld. and Labr. (Nfld.), Que., Yukon, Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.

Discussion

Athyrium distentifolium var. americanum differs from var. distentifolium of Europe in its more finely dissected leaves with crenulate pinnule-segments, relatively broader pinnae with abruptly larger basal pinnules, and much more rudimentary indusia, if any. Japanese plants are more similar to var. americanum than to var. distentifolium, and they need further study.

Selected References

None.

Lower Taxa

None.
Acute (?) +  and Acuminate (?) +
Masahiro Kato +
(Butters) Boivin +
brown;dark-brown +
persisting +
swollen +
simple to commonly +
55 cm550 mm <br />0.55 m <br /> (65 cm650 mm <br />0.65 m <br />) +
15 cm150 mm <br />0.15 m <br /> (?) +  and 55 cm550 mm <br />0.55 m <br /> (?) +
narrowed;2-3-pinnate-pinnatifid;lanceolate;elliptic +
reduced +
broadest;3cm;25cm +
roundish +
American alpine lady fern +  and athyrie alpestre sous-espèce américaine +
Greenland +, Alta. +, B.C. +, Nfld. and Labr. (Nfld.) +, Que. +, Yukon +, Alaska +, Calif. +, Colo. +, Idaho +, Mont. +, Nev. +, Oreg. +, Utah +, Wash. +  and Wyo. +
600–3100 m +
often +  and glabrous +
Wet talus slopes, rocky hillsides, alpine meadows +
scale-like +
monomorphic +
7 cm70 mm <br />0.07 m <br /> (10 cm100 mm <br />0.1 m <br />) +
redbrown +  and straw-colored +
0.5 times length of blade;0.5 times length of blade +
10 cm100 mm <br />0.1 m <br /> (30 cm300 mm <br />0.3 m <br />) +
short-stalked +
pinnatifid +
sessile +  and short-petiolulate +
Naturaliste Canad. +
round +, cuplike +, hoodlike +, reniform +, falcate +  and linear +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
persistent +
13 cm130 mm <br />0.13 m <br /> (?) +
lanceolate;lanceolate +
crenate +  and serrulate +
straight +
persistent +
with narrow sinus +  and attached +
discrete +
round +  and elliptic +
reniform +  and oblong +
dictyostelic +, unbranched +  and branched +
short-creeping +  and ascending +
Athyrium alpestre var. americanum +, Athyrium americanum +, Athyrium americanum subsp. americanum +, Athyrium alpestre var. gaspense +  and Athyrium distentifolium subsp. americanum +
Athyrium distentifolium var. americanum +
Athyrium distentifolium +
variety +
epiphytic +  and hemiepiphytic +