OregonFlora: Botrychium hesperium

	Botrychium hesperium
	western moonwort
Habit	Plants 5–20 cm tall above ground.
Spores	37(29–50) μm.
Common stalks	well developed; greater than 3 cm, with a reddish brown stripe below the trophophore.
Trophophores	short-stalked (stalk usually shorter than distance between first and second pairs of pinnae); blade pinnate-pinnatifid, subdeltate; to 5 cm long; dull gray-green and usually appearing glaucous; pinnae ascending, usually overlapping; ovate to lanceolate, broadly attached to the rachis; broadest at or below the middle, asymmetrically lobed with basiscopic lobes enlarged; pinnae lobes with rounded apices; the margins slightly rolled; lowest pinnae often exaggerated; up to twice as long as the adjacent pinnae; sporangia rarely present on pinnae margins.
Sporophores	erect with stalk up to 2 times as long as the trophophore at spore release; in larger plants becoming ternately branched with lateral branches nearly as long as main axis.
2n	=180 (allotetraploid, derived from B. lanceolatum and an unknown diploid).

	Botrychium hesperium
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	At upper montane to subalpine elevations in open, mesic meadows with low, herbaceous cover. Also in historically disturbed areas with gravelly soil, such as road shoulders, ski slopes, or mine tailings. 1400–1700 m. BW. ID, WA; western North America. Native. Unpublished forms with deeply lobed pinnae (B. hesperium var. ��fenestratum’ and B. ‘venulosum’) do not warrant taxonomic recognition.
Source	Flora of Oregon, volume 1, page 90 Ben Legler
Sibling taxa	B. ascendens, B. crenulatum, B. lanceolatum, B. lineare, B. lunaria, B. minganense, B. montanum, B. paradoxum, B. pedunculosum, B. pinnatum, B. pumicola, B. simplex
Web links	Local floras: BC, OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Botrychium hesperium

western moonwort

Habit

Plants 5–20 cm tall above ground.

Spores

37(29–50) μm.

Common stalks

well developed; greater than 3 cm, with a reddish brown stripe below the trophophore.

Trophophores

short-stalked (stalk usually shorter than distance between first and second pairs of pinnae);

blade pinnate-pinnatifid, subdeltate; to 5 cm long; dull gray-green and usually appearing glaucous;

pinnae ascending, usually overlapping; ovate to lanceolate, broadly attached to the rachis; broadest at or below the middle, asymmetrically lobed with basiscopic lobes enlarged;

pinnae lobes with rounded apices; the margins slightly rolled; lowest pinnae often exaggerated; up to twice as long as the adjacent pinnae;

sporangia rarely present on pinnae margins.

Sporophores

erect with stalk up to 2 times as long as the trophophore at spore release; in larger plants becoming ternately branched with lateral branches nearly as long as main axis.

=180 (allotetraploid, derived from B. lanceolatum and an unknown diploid).

Botrychium hesperium

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

At upper montane to subalpine elevations in open, mesic meadows with low, herbaceous cover. Also in historically disturbed areas with gravelly soil, such as road shoulders, ski slopes, or mine tailings. 1400–1700 m. BW. ID, WA; western North America. Native.

Unpublished forms with deeply lobed pinnae (B. hesperium var. ��fenestratum’ and B. ‘venulosum’) do not warrant taxonomic recognition.

Source

Flora of Oregon, volume 1, page 90
Ben Legler

Sibling taxa