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BFNA Title: Helodium 55.
HELODIACEAE Ochyra Patricia M. Eckel Plants small to rather robust, in soft, loose
green or yellowish or brownish green tufts or mats. Stems creeping to spreading and erect-ascending, regularly 1(--2)
pinnate, not stipitate, forming a flat frond with a strong primary axis,
branches distally tapered; stem section with hyalodermis lacking, sclerodermis
of 3(--4) thick-walled cells, central cylinder of large, firm-walled cells,
with or without a small central strand; paraphyllia densely felting stems and
branches, filiform to narrowly foliose, marginal cells ciliate or toothed and
ciliate, cell surface smooth; terminal cell (15--)20--25(--30):1;
pseudoparaphyllia lanceolate-foliose, marginal cells ciliate or toothed and
ciliate, cell surface smooth or proximally 1-papillose, the apical cells of
both paraphyllia and pseudoparaphyllia long and sharply acute, without
papillae; rhizoids smooth or minutely papillose, scattered on stems between
the leaves or at tips of branches; axillary hairs with 1--2 short, brown
basal cells and 2--3(--4) hyaline oblong distal cells. Stem leaves erect to erect-spreading when moist,
ovate-lanceolate, rounded-cordiform to triangular-cordate, base abruptly
narrowed to the insertion, scarcely to distinctly narrowly decurrent,
abruptly to more gradually acuminate beyond the middle, concave, striate to plicate-sulcate;
margins strongly and irregularly recurved, proximal margins
fimbriate-ciliate, median and distal margins serrulate-dentate to crenulate
more or less throughout; costa single, strong, ending at base of or before
the acumen or near the apex, rarely excurrent, smooth or with low or coarse
teeth on the proximal surface, paraphyllia usually abaxial at base; stem leaf
cells pellucid, subquadrate to
long-rectangular, thin-walled or incrassate, adaxially essentially smooth to
low or coarsely 1-papillose, abaxially 1-papillose centrally over the lumen
or more often near the distal ends to prorulose, never pluripapillose, apical
cells sharply pointed and smooth; alar cells not or poorly differentiated. Branch leaves mostly similar to stem
leaves but shorter, becoming ovate (not triangular-cordiform) in Echinophyllum, with smooth, elongate
apical cells. Specialized asexual
reproduction absent. Sexual
condition dioicous or autoicous; perigonia and perichaetia seated and
lateral on the stems, perichaetia erect, oblong-lanceolate, abruptly and
slenderly long-acuminate, plicate; margins of perichaetial leaves subentire
proximally, distally irregularly denticulate to shortly ciliate, recurved on
one or both sides, with costa ending in the acumen before the apex, distal
cells linear or oblong-linear, smooth to minutely prorulose, walls thin or
incrassate. Seta elongate, smooth, reddish orange. Capsule strongly inclined to horizontal, arcuate and asymmetric, or straight,
cylindric; annulus differentiated, well-developed, revoluble, of (2--)3-4 rows of
cells; operculum straight, conic or rostellate-rostrate, blunt or apiculate;
peristome hypnoid; peristome teeth yellow to yellow-brown; exostome teeth 16,
lanceolate, yellowish, connate and cross-striolate proximally, papillose
distally; endostome segments lanceolate, hyaline to yellow, basal membrane
high, distal segments alternating with groups of (2--)3--4 long, slender, subcoalescent, appendiculate
or nodulose cilia. Calyptra
cucullate, naked. Spores globose,
minutely papillose (10--)11--15(--16) \um. Genera 4 (2 in
the flora): mostly temperate zone, Northern Hemisphere. Genera of
Helodiaceae are generally branching once-pinnate from a single axis, have a
single costa to the leaf middle or beyond, and rather elongate median leaf
cells, (5--)7--10(--18):1. Abaxial portions of the stem leaves are smooth, or
with a single, central papillae over the lumina, but all generally are
characterized by papillae located at or near the distal end of the cell, or
the cells are prorulose, or both. Stem and branch leaf apical cells are
essentially smooth and sharply pointed (not truncate or multi-papillose). The
stems are somewhat to densely tomentose with conspicuous complex slender
smooth-walled paraphyllia and smooth to proximally unipapillose
pseudoparaphyllia whose apical cell is also sharply pointed and smooth on
surface and margins. These structures also develop as appendages from the
proximal margins of the stem and branch leaves. Strong, pointed teeth in the
proximal region, as in H. blandowii and
Echinophyllum, are variously
antrorsely and retrorsely curved. Leaves of the Helodiaceae
characteristically have fimbriate, elongate, paraphyllia-like appendages at
the basal margins of the stem leaves. The terminal cell of the paraphyllia of
species of Thuidium (Thuidiaceae)
as well as that of the branch leaves is (sub)quadrate, truncate and
multipapillose, the apical cell coronate-papillose, not smooth and sharply
pointed as in species of Helodium and Echinophyllum. Heterocladium has an indistinct or short (ending at
the leaf middle or before) and simple, or double leaf costa. Haplocladium also has a similar
terminal paraphyllia cell, but with sparse to abundant paraphyllia with
short, subquadrate cells, and with leaf cells abaxially bearing a single,
stout papilla over the lumen. Claopodium
has no or few and inconspicuous paraphyllia and a papillose seta. Thelia (Theliaceae) species have
terete-julaceous habits, complex-branched laminal papillae, erect leaf
margins, peristomes that are densely papillose and lack cilia, or, in Thelia hirtella, with long, regularly
antrorsely curved unbranched papillae on the distal leaf margins. According to
W. Frey (2009), the separation of the Helodiaceae from the Thuidiaceae is not
substantiated by molecular analyses, although there are rather distinct
morphological differences between the Helodioid genera, and the
Thuidioid---Helodioid genera have median or distal cells, or both,
linear-rhomboidal, with alar cells differentiated, but otherwise the plants
are very similar. Helodiaceae is
retained as a family by B. Goffinet et al. (2009), and clearly the family is
in the process of definition. Crosby et al. (1999) cited four genera for the
family, including Helodium,
Echinophyllum (as Bryochenia), Actinothuidium, and Palustriella. SELECTED
REFERENCES Best, G. N. 1896. Revision of the North American Thuidiums. Bull. Torrey Bot. Cl. 23:
78--90. Crosby, M. R., R. E. Magill, B. Allen, and Si He. 1999. A Checklist
of the Mosses. Release Dec. 20, 1999. St. Louis. Goffinet, B., W. R. Buch and
A. J. Shaw. 2009. Morphology, anatomy and classification of the Bryophyta. In
B. Goffinet and A. J. Shaw, eds. Bryophyte Biology, Second Edition.
Cambridge. Pp. 55--138. Frey, W., ed. 2009. Syllabus of Plant Families: A.
Engler's Syllabus der Pflanzenfamilien. Part 3. Bryophytes and seedless
Vascular Plants. Berlin. 1.
Autoicous; strictly 1-pinnate, median
stem leaf cells elongate, mostly 7--10(--18):1; costa of stem leaf
essentially smooth or with 1--2 teeth over the surface in proximal half;
inner perichaetial leaves without cilia, apical cell of stem and branch
leaves 6--7:1; abaxial leaf cells roughened with small and delicate papillae;
stem and branch leaves similar in shape; paraphyllia with minute
denticulations on the distal cell ends of the cilia, branched-filiform . . .
1. Helodium, p. XXX 1. Dioicous;
irregularly 1--2-pinnate; median stem leaf cells subquadrate to
short-rectangular, mostly (5--)6:1; costa of stem leaf with coarse, spinose
teeth over the surface in proximal half; inner perichaetial leaves ciliate;
apical cell of stem leaves ca. 20:1, branch leaves ca. 7:1; abaxial leaf
cells echinate with coarsely obliquely blunt-conic papillae; stem leaves cordiform,
branch leaves ovate; paraphyllia with irregular coarse teeth on the cilia
margins, laciniate-foliose and branched-filiform . . . 2. Echinophyllum, p. XXX 1. HELODIUM Warnstorf, Krypt.-Fl. Brandenburg, Laubm.,
675, 692. 1905, conserved name * [Greek (h)elos,
low ground by a river, a marsh or
marsh-meadow, eidos, resemblance,
and Latin -ium, diminutive noun
suffix, alluding to the habitat] Patricia M. Eckel Plants medium to large, in soft, loose, tufts
or mats, green to yellow-brown. Stems
ascending to erect, freely branched and regularly 1-pinnate, with or without
a stem central strand; paraphyllia densely felting stems, branches, leaf
bases, the abaxial surface of the costa at the leaf base, both filiform and
narrowly lanceolate-foliose, (1--)2(--3) seriate at insertion, cell surface
smooth, simple, more often branched, cells long-rectangular, to 20:1,
marginally essentially smooth to distally 1-papillose or prorulose at cell
ends only, terminal cell lanceolate, smooth, thin-walled or somewhat thicker-walled
at the tip; pseudoparaphyllia lanceolate-foliose, cells
(1--)2--4(--5)-seriate at the insertion, 3--5(--7) cells elongate, with
margins serrulate with lateral teeth, proximal cells subquadrate, short- to
long-rectangular, cell surface smooth, terminal cell as in paraphyllia. Stem and branch leaves erect or erect-spreading,
ovate-lanceolate to rounded-cordiform, abruptly to gradually tapered into a
flat or channeled, broad or attenuate, often twisted acumen; proximal margins
irregularly revolute or strongly and
broadly or narrowly revolute to the apex; proximal to median margins
fimbriate-ciliate with paraphyllia-like appendages, medially entire and
minutely toothed near the apex; or with short, sharp teeth from projecting
distal cell ends throughout; costa single, rather strong, ending at or before
the acumen base, or in the acumen, or rarely percurrent, essentially smooth
or with 1--2 teeth near the insertion; stem leaf cells pellucid, enlarged and
laxly rectangular along the insertion, medially and distally thin-walled or
incrassate, length heterogeneous, mostly linear-rectangular to
linear-fusiform, 7--10(--18):1, apical cell of stem and branch leaves 6--7:1;
adaxially smooth or 1-papillose, abaxially 1-papillose centrally over the
lumen or more often near the distal ends, apical cell variously distally
somewhat thickened, sometimes with a low papilla. Sexual condition autoicous; perichaetial leaf margins subentire
proximally, eciliate, distally regularly denticulate or irregularly and
sharply dentate. Capsule smooth, brown, stomata present in the short
neck. Species 2 (2
in the flora): Greenland, North Temperate Zone. The marginal
cells of the leaf in the acumen of both species of Helodium are shorter than the cells in the middle of the acumen
and converge at the apex to produce a smooth cell generally shorter than
other cells in the acumen. In Echinophyllum
sachalinense the smooth apical cell of the acumen becomes more elongated
than the cells proximal to it in both stem and branch leaves. In Echinophyllum the pseudoparaphyllia
are papillose, but smooth in Helodium. The
distal medial cells of the stem leaves are short and thick-walled
(parenchymatous), but long-rectangular and relatively to distinctly
thin-walled (prosenchymatous) in Helodium
(T. O’Brien and D. Horton 2000). The cells near the base of the costa are
larger and laxer, and more pale than cells distal to this area, whereas in Echinophyllum they are thick-walled
and short-rectangular to (sub)quadrate
and concolorous. The perichaetial leaves of the two species of Helodium are nearly smooth throughout
and bordered by minute, uniform denticulations, or sharply, distantly and
irregularly toothed from distal cell ends. In Echinophyllum, the margins are sparsely short-ciliate with hyaline,
long-celled, narrow teeth composed of (1--)2 elongate cells, free but closely
parallel to the edge of the lamina. When dry, the dense paraphyllia felting
the stems appear like cobwebs. The habitat of Helodium blandowii is mostly hydric, associated with wet
substrates, whereas Echinophyllum occurs
in more mesic places, on drier humus, bark or rock (T. O’Brien and D. Horton
2000). Helodium paludosum seems to
be intermediate in habitat preferences and able to tolerate seasonal
desiccation. SELECTED REFERENCES Abramova, A. L. and I. I. Abramov. 1972. On
the span of the genus Helodium
(Sull.) Warnst. J. Hattori Bot. Lab. 35: 371--381. O’Brien, T. J. and D.
Horton. 2000. Bryochenea (Musci;
Thuidiaceae) is Cyrto-hypnum
(Thuidiaceae), but B. sachalinensis
is Echinophyllum (Thuidiaceae), a
new genus from the Pacific Rim. Bryologist 103:509-517. Watanabe, R. 1972. A
revision of the family Thuidiaceae in Japan and adjacent areas. J. Hattori
Bot. Lab. 36: 171--320. 1. Stem
without central strand; paraphyllia long, dense, floccose; leaves shortly
rounded-cordate; stem leaves short-acuminate; leaves yellow, yellow-green,
often bright red-orange at insertion and paraphyllium bases; stem leaf cells
rather thick-walled, rounded at the corners, abaxially strongly 1-papillose
centrally or nearer the distal ends of the lumen; costa with 1--2 scattered
teeth along the proximal abaxial surface . . . . 1. Helodium blandowii 1. Stem with
central strand; paraphyllia scattered and short; leaves longly
ovate-lanceolate; stem leaves slenderly long-acuminate, pale green, nearly
hyaline at insertion and paraphyllium bases; stem leaf cells rather
thin-walled, angular at the corners, abaxially essentially smooth or weakly
papillose because of projecting distal angles; costa essentially smooth
proximally. . . . .2. Helodium paludosum 1. Helodium blandowii (F. Weber & D. Mohr) Warnstorf,
Krypt.-Fl. Brandenburg Laubm., 692. 1905 Hypnum blandowii F. Weber & D. Mohr, Bot.
Taschenbuch, 332. 1807 Plants rather large in yellow to
yellowish-green mats. Stems red-brown,
closely and strictly 1-pinnate, more loosely pinnate in one variety; branches
simple, nearly equal, straight, widely spreading, paraphyllia abundant on
stems and branches in long, tangled masses, central strand absent. Stem and branch leaves rather close
and overlapping, more erect than spreading when moist, rounded-cordiform,
stem leaves 1.2--1.5 mm, branch leaves 0.6--0.8 mm, both sulcate-plicate,
rather abruptly tapered into a broad, channeled, rather short acumen, margins
erect-incurved in the acumen, denticulate with short, sharp teeth from
projecting distal cell ends throughout;
costa with 1--2 scattered teeth along the proximal abaxial surface; stem
leaf cells incrassate, oblong-fusiform or oblong-rhomboidal, with rounded
angles, abaxially strongly 1-papillose centrally or nearer the distal ends of
the lumen. Perichaetial leaves with
short, irregularly spaced, distant, sharply variously antrorsely to
retrorsely pointed teeth on distal margins, regularly denticulate in the
acumen. Seta 40--60 mm. Capsule 3-4 mm. Varieties 2 (2
in the flora): Greenland, North Temperate Zone. The marginal
teeth of the leaves of Helodium
blandowii, especially proximally and medially, are sharply
dentate-serrate, whereas the margins of
H. paludosum are nearly smooth. The papillae, though narrow, are elevated
and, especially as seen on branch leaves, antrorsely curved, like those in Echinophyllum, but much more delicate.
The length of the seta of H. blandowii (4--6
cm) is more than twice that of H. paludosum (2--2.8 cm) and the
capsules are larger (3--4 mm in H.
blandowii, but 2--2.5 mm in H.
paludosum). 1. Stems
erect, evenly and strongly pinnate, with branches nearly equal; costa ending
at or before base of leaf acumen . . . . 1a. Helodium blandowii var. blandowii
1. Stems spreading, loosely subpinnate, with
unequal branches; costa ending near the leaf apex . . . . 1b. Helodium blandowii var. helodioides 1a. Helodium blandowii var. blandowii Stems erect,
evenly and closely pinnate, branches subequal, costa ending at the base of or before leaf acumen. Capsules
mature spring. Hydric soils of open or wooded fen, muskeg, wet habitats,
along streams, edges swamp forests, open fens, wet bases of trees in hummocks
in peat bogs and bogs of Thuja
occidentalis, tundra benches and gravel bars of creeks, calciphile;
moderate to high elevations; Greenland; Alta., B.C., Man., N.B., Nfld. and
Labr. (Nfld. and Labr.), N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask.,
Yukon; Alaska, Ariz., Calif., Colo., Conn., Ga., Idaho, Ill., Iowa, Maine,
Mass., Mich., Minn., Mont., Nebr., Nev., N.J., N.Y., N.C., N.Dak., Ohio,
Oreg., Pa., S.Dak., Utah, Vt., Wash., Wis., Wyo.; Eurasia. 1b. Helodium blandowii var. helodioides (Renauld & Cardot ex Röll) H. A. Crum, Steere
& L. E. Anderson, Bryologist 68: 432. 1965 [1966] E Thuidium helodioides Renauld & Cardot ex Röll, Hedwigia
32: 308. 1893; Elodium paludosum var.
helodioides (Renauld & Cardot
ex Röll) Best; Helodium paludosum var.
helodioides (Renauld & Cardot
ex Röll) Grout Stems
spreading, loosely subpinnate, with unequal branches, costa ending near the
leaf apex. Soil, logs,
swampy woods; moderate elevations; Ont.; Ind., Iowa, Mass., Mich., N.J.,
N.Y., Ohio, Pa; Vt. Thuidium helodioides was regarded by A. J. Grout (1934) as a
variety of H. paludosum as did Best
(1896) before him. The variety was transferred from H. paludosum to that of H.
blandowii by H. A. Crum et al. (81965) in preparation for their checklist
of North American mosses. According to G. N Best (1896) the variety was
growing with the typical variety (of Helodium
paludosum var. paludosum). The
spelling of the varietal epithet follows Art. 60A of the ICBN (McNeill 2006),
which recommends classical usage and the transcription of the Greek spiritus
asper as the letter h, correcting the common variant “elodioides.” SELECTED
REFERENCES Grout, A. J. 1934. Leskeaceae. In A. J. Grout, ed. Moss Flora of
North America North of Mexico. 3: 179--180. Newfane, Vermont. Crum, H., W. C.
Steere and L. E. Anderson. [1966] 1965. Some additional new names for North
American mosses. Bryologist 68: 432--434. Grout, A. J. 1934. Leskeaceae. In
A. J. Grout, ed. Moss Flora of North America North of Mexico. 3: 179--180.
Newfane, Vermont. McNeill, Chairman. 2006. International Code of Botanical
Nomenclature (Vienna Code). Ruggell, Liechtenstein. 1. Helodium paludosum (Austin) Brotherus in A. Engler &
K. Prantl, Nat. Pfanzerfam. 1(3): 1019. 1908 Elodium paludosum Austin, Musci Appalach., 306. 1870; Thuidium paludosum (Austin) Rau &
Hervey Plants of medium size, rather delicate, in
pale green or yellow-green mats. Stems
green, loosely 1-pinnate; branches often unequal, flexuose, widely spreading,
paraphyllia scattered and short, central strand present. Stem and branch leaves rather distant on the stem, wide-spreading
when moist, ovate-lanceolate, stem leaves 1.5--1.8 mm, branch leaves 0.9--1.5
mm, both striate-plicate, rather gradually slenderly tapered into a rather
long, flat acumen, margins plane in the acumen, nearly smooth proximally and
minutely serrulate or sinuate-serrulate distally; costa smooth, 4/5 leaf length, subpercurrent; stem leaf cells
rather thin-walled, long-rectangular to linear, angular at the corners,
abaxially essentially smooth or weakly papillose-prorulose because of
projecting distal ends of the lumen. Perichaetial
leaves regularly denticulate on distal margins. Seta 20--28 mm. Capsule
2--2.5 mm. Capsules
mature spring. Hydric soils of fens, marshes, hummocks in swamps, logs, base
and roots of Alnus, seepage,
depressions in wet woods and thickets, grassy wet meadows and bottomlands, wet tree bases, Taxodium distichum swamps in southern
areas, often near springs, dry summer soils, seasonally submerged, seasonally
wet areas, dried sinkhole ponds, tops of hills and mountains in brushy
marshes; low to moderate elevations; B.C., N.S., Ont., Que., Ala., Alaska,
Conn., Del., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Miss., Mo.,
N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Tenn., Vt., Va., W.Va., Wis., e
Asia. Helodium paludosum is sometimes difficult to distinguish
from H. blandowii in the southern
part of its range, but the key above is usually adequate. The latter tolerates
drier situations (H. N. Best 1896). |
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