E. limosum L., Sp. pl. 1062. 1753.
E. heleocharis Ehrh., Hannov. Mag. 21: 286. 1783.
E. maximum Lam., Fl. Franc. 1: 7. 1778. (As to type, according to Reed, 1971).
Description:
Stems homophyadic, 35-113 cm tall (m 74.2) with internodes 2.5-5 cm
long (m 3.9) and 2.5-9 mm in diameter (m 5.3), having 12-24 ridges
(m 15.5); these often obscure and therefore the stems smooth.
Internally there is only carinal collenchyma, chlorenchyma is continuous
under the valleys, and interrupted under the collenchyma. Central
canal large, about 9/10 diameter of the stem, vallecular canals absent.
Endodermis individual around each vascular bundle.
Sheaths squarish, 4.5-9 mm long (m 6.4), 4-10 mm wide (m 6.5), with
short (2-3 mm long, m 2.5) narrow, dark teeth.
Branches from middle nodes only, spreading, often absent, with the
first internode shorter than stem sheath (in northern North America
equaling it), (2)3-5(8) mm long (m 3.5 Eurasia, 4.6 North America)
with 4-6 ridges (m 4.5), the silica profile of blocky tubercules. Larger
branches resemble small stems. Branch teeth narrowly pointed,
commissure about 0.4 mm long, with distinct "kettenlinie" but without
furrow of anchoreells. Valleys rounded, with stomata scattered across
the valley or tending to be in bands on either side. Silica pilules
scattered over surface of stomate, outlining it and lining the stoma.
Mamillae transversely aligned, distinct. Branches hollow.
Cone 12-20(30) mm long (m 17.6) on peduncles 8-20(37) mm long (m 12.8).
Rhizome smooth, light brown, glabrous, with black roots. (According
to Dioscorides the name "horsetail" refers to the appearance of these
black roots resembling black hairs of a horse's tail.)
Spores 34-45 µm in diameter (m 40).
Gametophytes with plates often becoming filamentous at tips, sparse
or absent on the male. Antheridia exserted, 6-8 times longer than
wide, with 4-9 (mostly 8) cap cells, these elongated to form a corona at
dehiscence. Archegonial neck cells conspicuously elongated.
Type:
Linnaean Herbarium (LINN). Packet 1241 sheet 6! (According
to Newman, cited by Milde, 1867a, p. 58, Linnaeus wrote "4. fluviatile"
on the sheet and Smith wrote "limosum? certe." Hauke (1978) observed that
whoever wrote the latter, had crossed out Linnaeus' identification.
This specimen was in the herbarium in 1753. We can therefore
consider it the holotype.
Seasonality:
May to August.
Distribution:
North America south to Virginia, Ohio, Iowa, Nebraska,
Wyoming, and Oregon. Eurasia south to the Mediterranean, Albania,
Bulgaria, Crimea and across Asia to Korea, and Japan. Schaffner and
Li (1939) reported it from Yunnan, China.
Ecology:
Sunny, wet places, as ponds, ditches, marshes, swales.
Standing in water.
Discussion:
Linnaeus considered the branched and unbranched forms
as separate species, E. fluviatile and E. limosum. Subsequently, there
was some confusion of E. fluviatile with E. telmateia, and Lamarck's
E. maximum apparently applies to both, since his description is of E.
telmateia, but he listed E. fluviatile as a synonym, the type (according
to Reed, 1971) is E. fluviatile, and, according to Milde (1867a, p. 260)
specimens of E. telmateia in Lamarck's herbarium were labeled E.
fluviatile. Pollich (1777) first united the two Linnaean species under
the name E. fluviatile, according to Milde (1867a, p. 354) and
Schaffner (1931). Ehrhart (1783) also united them, under the name E.
heleocharis, and subsequent workers have united them under the
name E. limosum. Since these two Linnaean names were first united
by Pollich, his selection of E. fluviatile stands as the correct name for
this species.
Although Hauke (1978) had seen few specimens from Asia, Novak (1971) includes
Asiatic USSR, Mongolia, and Korea in the range of this species, and
Ohwi (1965) lists Sakhalein, Korea, Hokkaido and Honshu.
Schaffner's citation of Yunnan, China, seems questionably disjunct.
HAUKE, R.L. (1978)
A taxonomic monograph of the genus Equisetum subgenus Equisetum.
Nova Hedwigia 30, p385.
back to homepage