Burke: Equisetum palustre vs. Equisetum arvense

	Equisetum palustre	Equisetum arvense
	marsh horsetail	common horsetail, field horsetail
Habit	Rhizomatous annual, the stems not dimorphic, 2-8 dm. tall, with 5 to 10 deep grooves, the ridges smooth; stomates in a single, broad band in each furrow; central cavity less than 1/3 the diameter of the stem; sheathes green, 5-10 mm. long, with persistent teeth 3-7 mm. long, black or dark brown with broad, pale, papery margins.	Rhizomatous perennial, the stems dimorphic; sterile stems 1.5-6 dm. tall and 1.5-5 mm. thick, prominently 10- to 12-ridged, the central cavity about 1/4 the diameter of the stem; stomates in 2 broad bands in the furrows; sheath 5-10 mm. long, greenish, with teeth 1-3 mm. long, free, firm and brown; fertile stems brownish to whitish, soon withering, simple, up to 3 dm. tall and 8 mm. thick, with sheaths 14-20 mm. long, and large teeth 5-9 mm. long.
Leaves	Branches few and irregular to many and whorled, 5- to 6-angled, simple.	Branches only on sterile stems, whorled, ascending, 3- or 4-angled, solid, 1-1.5 mm. thick, sometimes again branched.
Spores	Cones pedunculate, blunt, deciduous.	Cone 0.5-3.5 cm. long, long-pedunculate, blunt.

	Equisetum palustre	Equisetum arvense
Habitat	Streambanks, wet meadows, and marshes, from the lowlands to moderate elevations in the mountains.	Moist to moderately dry, often disturbed places, from the lowlands to the subalpine.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across the northern U.S. and Canada to the Atlantic Coast; circumboreal. [WildflowerSearch map] [BONAP county map]	Widely distributed on both sides of the Cascades crest in Washington; Alaska to California, east across North America, except for the south-central and southeastern U.S., to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]
Origin	Native	Native
Conservation status	Not of concern	Not of concern
Sibling taxa	E. arvense, E. ×ferrissii, E. fluviatile, E. hyemale, E. laevigatum, E. ×litorale, E. ×mackaii, E. ×nelsonii, E. scirpoides, E. sylvaticum, E. telmateia, E. variegatum	E. ×ferrissii, E. fluviatile, E. hyemale, E. laevigatum, E. ×litorale, E. ×mackaii, E. ×nelsonii, E. palustre, E. scirpoides, E. sylvaticum, E. telmateia, E. variegatum
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, 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	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, 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

Equisetum arvense

marsh horsetail

common horsetail, field horsetail

Habit

Rhizomatous annual, the stems not dimorphic, 2-8 dm. tall, with 5 to 10 deep grooves, the ridges smooth; stomates in a single, broad band in each furrow; central cavity less than 1/3 the diameter of the stem; sheathes green, 5-10 mm. long, with persistent teeth 3-7 mm. long, black or dark brown with broad, pale, papery margins.

Rhizomatous perennial, the stems dimorphic; sterile stems 1.5-6 dm. tall and 1.5-5 mm. thick, prominently 10- to 12-ridged, the central cavity about 1/4 the diameter of the stem; stomates in 2 broad bands in the furrows; sheath 5-10 mm. long, greenish, with teeth 1-3 mm. long, free, firm and brown; fertile stems brownish to whitish, soon withering, simple, up to 3 dm. tall and 8 mm. thick, with sheaths 14-20 mm. long, and large teeth 5-9 mm. long.

Leaves

Branches few and irregular to many and whorled, 5- to 6-angled, simple.

Branches only on sterile stems, whorled, ascending, 3- or 4-angled, solid, 1-1.5 mm. thick, sometimes again branched.

Spores

Cones pedunculate, blunt, deciduous.

Cone 0.5-3.5 cm. long, long-pedunculate, blunt.

Equisetum palustre

Equisetum arvense

Habitat

Streambanks, wet meadows, and marshes, from the lowlands to moderate elevations in the mountains.

Moist to moderately dry, often disturbed places, from the lowlands to the subalpine.

Distribution

Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across the northern U.S. and Canada to the Atlantic Coast; circumboreal.

[WildflowerSearch map]

[BONAP county map]

Widely distributed on both sides of the Cascades crest in Washington; Alaska to California, east across North America, except for the south-central and southeastern U.S., to the Atlantic Coast.

[WildflowerSearch map]

[BONAP county map]

Origin

Native

Conservation status

Not of concern

Sibling taxa