Equisetum pratense Ehrh., Hannover. Mag. 22: 138. 1784.
E. umbrosum J.G.F. Meyer ex Willd., Enum. Pl. hort. reg. Berol. 1065. 1809.
Description:
Stems heterophyadic, the vegetative 16-53 cm tall
(m 32.7), with internodes 1.8-3.8 cm long (~ 2.8) and 1-3 mm in diameter
(m 1.9), having 8-18 ridges (m 12.9), those on upper branched
internodes bearing long, thin silica spicules. (Specimens from
Siberia and China may have spicules on lower internodes as well).
Internally with prominent carinal and vallecular collenchyma,
and chlorenchyma present under the ridges only. Central canal
about 1/6 to 1/3 diameter of the stem, endodermis outer common.
Sheaths somewhat elongated, 3-5 mm long (m 4.2), 2-4.5
mm wide (m 3.1), with narrow teeth 1.5-4 mm long (m 2.3) having
dark centers and white margins. Sheath segments slightly grooved.
Branches in regular whorls from upper internodes, horizontal
to drooping, with the first internode 2-5 mm long (m 3.5), nearly
equaling subtending stem sheath of lower most whorls, but longer
than subtending sheath of upper internodes (in which the sheaths
deerease in size). Ridges 3 (occasionally 4 in specimens from
Siberia, and China) lacking a silica profile. Teeth deltoid, slightly
incurving, with thin white margins. Commissure long, weakly furrowed,
with indistinct anchorcells. Valleys channeled, with stomata in
a single (occasionally double) line on each side. Silica pilules
clustered near stoma, sparse and obscure on remainder of stomate.
Mamillae small, in longitudinal rows. Branches solid.
Coniferous stems initially non-green and unbranched,
with larger sheaths and longer teeth, becoming green and branched
after the spores are shed.
Cones 20-25 mm long (m 21) on peduncles 20-48 mm long
(m 31).
Rhizomes dull, black, not rough, with hairs only on sheaths.
Spores 34-42 µm in diameter (m 38).
Gametophytes (Buchtien, 1889) Plates with pointed tips,
sparse or absent on the males. Antheridia protuberant, two times
longer than wide, with 2-7 cap cells.
Type:
Ehrhart "bei Steige im Fürstenthum Blankenburg".
Novak (1971) said this specimen was in G-DC. According to the
curator there (in lit.) it is not, but in GOET there is
a specimen of E. pratense from the herbarium of G.W. Meyer collected
by Ehrhart at Stiege in 1782, and designated as lectotype by H.P.
Fuchs in an annotation dated 1954. Hauke has seen a photograph
of this specimen and agrees with Fuchs' designation.
Seasonality:
Coning in May and June.
Distribution:
North America south to New Jersey, New York, Michigan, Illinois,
Iowa, North Dakota, Montana, Idaho and British Columbia. Eurasia
south to Britain, Germany, Switzerland, Austria, Hungary, USSR,
Manchuria, northern China, Korea, Hokkaido (Japan).
Ecology:
Semi-shade or sun, of moist woods or meadows.
Discussion:
This species, although having the same distribution as others
such as E. palustre, E. fluviatile and E. sylvaticum,
is less frequent than they are. Its deltoid branch teeth on horizontal
to drooping branches make it distinctive enough that it has been
generally recognized since the early 19th century. It appears
nearly uniform throughout its range, being slightly more robust
in Europe than in North America, and having greater silicification
and occasionally 4-angled branches in Siberia and northern China.
HAUKE, R.L. (1978)
A taxonomic monograph of the genus Equisetum subgenus Equisetum.
Nova Hedwigia 30, p385.
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