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BFNA Title: Dichelyma |
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2. DICHELYMA Myrin, Kongl. Vetensk.
Acad. Handl. 1832: 273. 1833 * [Greek dicha,
in two, and elyma, veil, alluding to
large dimidate or cucullate calyptra of the genus] Plants slender to robust, glossy, seasonally
inundated. Stems prostrate or
pendent, irregularly branched; paraphyllia absent; pseudoparaphyllia absent; axillary
hairs 100--300 \um; rhizoids from initials adaxial to the leaf insertions,
dark-red, not or irregularly branched. Leaves
3-ranked, distant or crowded, keeled and conduplicate, lanceolate to
linear-lanceolate, obtuse, acute or filiform-acuminate; margins entire or
obscurely serrulate proximally, serrate to serrulate distally; medial leaf
cells linear to linear-rhomboidal; alar cells firm-walled, quadrate or
rectangular, not or slightly enlarged; costa subpercurrent, percurrent,
excurrent to long-excurrent. Sexual
condition dioicous; perigonia gemmate, lateral, in leaf axils; perichaetial
leaves elongate, ecostate, sheathing the setae. Seta short or long. Capsule
immersed, laterally emergent, emergent or exserted, oval, oval-oblong,
subcylindric or cylindric, stomata absent; operculum conic, acute to
obliquely rostrate; exostome teeth
inserted, linear, trabeculae widely spaced, yellow, orange, or red, spiculose-papillose,
perforated along medial line; endostome segments linear, red to
brownish-orange, papillose, joined by lateral bars only distally (trellis
imperfect) or throughout (trellis perfect). Calyptra long-cucullate, covering the capsule and often clasping
the base of the seta when young. Spores
smooth or minutely papillose, spheric. Species 5 (4
in flora): North America, Europe, Dichelyma is a North Temperate genus of five
species, four of which occur in Dichelyma is often confused with species of Drepanocladus
(in the broad sense), which can be similar in aspect, size, color, and
habitat preference. Many Drepanocladus species, however, have inflated
alar cells, and they all differ from Dichelyma in having plane to
concave leaves that are often spirally twisted when dry, and not
three-ranked. In addition, the sporophytes of Drepanocladus have
exserted capsules with stomata, cross-striolate exostome teeth and a typical
endostome consisting of a basal membrane, segments and cilia. Blindia,
commonly found on rocks and boulders in and along streams, ponds, and lakes
has also been confused with Dichelyma. Blindia is acrocarpous and
much smaller. In addition, it has well-developed, inflated alar cells,
concave leaves, elongated setae, and a single, haplolepidous peristome.
Curiously, the aquatic form of Leptodictyum
riparium (fo. laxirete) has sometimes been mistaken for Dichelyma. This form of L. riparium is similar in size and
aspect to Fontinalis, but differs
in having leaves with long, single costae. It differs from Dichelyma in its larger size and in having
soft, well-spaced leaves that are concave or plane rather than keeled. 1. Capsules emergent or exserted from end of perichaetium; endostome
trellis perfect. 2. Leaves at stem and branch tips strongly falcate to circinate; medial
stem leaves 0.4--0.8 mm wide........................................................................ 4.
Dichelyma uncinatum 2. Leaves at stem and branch tips
flexuose-spreading to falcate; medial stem leaves 0.7--1.4 mm wide............................................................................... Dichelyma
falcatum 1. Capsules immersed or laterally
emergent; endostome trellis incomplete. 3. Leaves linear-lanceolate, setaceous;
costae long-excurrent 1. Dichelyma
capillaceum 3. Leaves lanceolate, slenderly acute
to obtuse; costae subpercurrent to excurrent......... ............................................................................................. 3.
Dichelyma pallescens Alternate key
to sterile material: 1. Leaves of stem and branch tips strongly falcate to circinate............ 4. Dichelyma uncinatum 1. Leaves of stem and branch tips
erect-ascending, flexuose-spreading, or falcate. 2. Medial stem leaves 0.7--1.4 mm wide................................. 2. Dichelyma
falcatum 2. Medial stem leaves 0.4--0.8 mm wide. 3. Leaves linear-lanceolate, setaceous;
costae long-excurrent....... 1. Dichelyma
capillaceum 3. Leaves lanceolate, slenderly acute
to obtuse; costae subpercurrent to excurrent . . . 3. Dichelyma pallescens 1. Dichelyma capillaceum
(Withering) Myrin, Kongl. Vetensk. Acad. Handl. 1832: 274. 1833 Fontinalis
capillacea Withering.,
Plants slender, to 20 cm, green to yellowish green, brownish at base; axillary
hairs 100--200 \um, 3--4 cells, basal cell quadrate, brownish, distal 2--3
cells long-cylindrical, hyaline. Leaves
weakly three-ranked, linear-lanceolate, filiform-acuminate, 4--7 mm; margins
plane; costa long-excurrent, serrulate at apex, occasionally serrulate at
base; medial cells 60--120 x 6--8 x \um; alar cells firm-walled, quadrate or
rectangular, slightly enlarged. Perichaetial
leaves to 7 mm, overtopping the capsule. Seta 3--5 mm. Capsule
immersed or laterally emergent, oblong-cylindrical, 1--2 mm; operculum obliquely
long-rostrate, 0.5--1 mm; exostome teeth spiculose-papillose; endostome brownish
orange, longer than exostome teeth, spiculose-papillose, trellis imperfect. Calyptra 1.5--3 mm. Spores 10--15 \um. Trunks and
branches of trees (Acer, Alnus, Carya,
Fraxinus, Gleditsia, Liquidambar, Nyssa, Populus, Taxodium, Thuja, Ulmus)
and shrubs (Cephalanthus), sticks,
and roots or on rocks and boulders along the edges of lakes, ponds, and
streams, often in seasonally submerged depressions in woods; low to moderate
elevations (0--390 m); Man., N.B., Nfld. and Labr. (Labr.), N.S., Ont., Que.;
Ala., Ark., Conn., Del., D.C., Fla., Ga., Ind., La., Maine, Md., Mass., Mich.,
Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., Tenn., Vt., Va.,
W.Va., Wis.; Europe. Dichelyma
capillaceum, the most common of
the species, is equally abundant on bark or rock. It is the most slender
species in Dichelyma and has indistinctly
keeled, weakly three-ranked leaves with long-excurrent costae. With a hand
lens D. falcatum and D. pallescens can be separated from D. capillaceum by their larger size
and strongly keeled, distinctly three-ranked, lanceolate leaves. Dichelyma uncinatum, also a slender
species, differs in having leaves of stem and branch tips strongly secund to
circinate, while those of D.
capillaceum are mostly erect or spreading. The sporophytes of D.
capillaceum and D. pallescens are more or less identical and the
two species are sometimes found growing together. Dichelyma pallescens further differs in having acute to obtuse
leaf apices. There is a 2. Dichelyma falcatum
(Hedwig) Myrin, Kongl. Vetensk. Acad. Handl. 1832: 274. 1833 Fontinalis
falcata Hedwig, Sp. Musc.
Frond., 299. 1801 Plants medium to robust, to 15 cm, green,
yellowish or yellow-brown; axillary hairs 200--300 \um, 5--7 cells, basal 1--2
cell(s) quadrate, brownish, distal 4--5 cells long-cylindrical, hyaline. Leaves strongly three-ranked, lanceolate,
acute, acuminate or subulate, 3--5 mm; margins plane or very narrowly
recurved, entire proximally, serrulate distally; costa subpercurrent,
percurrent to variously excurrent; medial leaf cells 120--200 x 6--8 x \um;
alar cells firm-walled, quadrate or rectangular, not or slightly enlarged. Perichaetial leaves to 7 mm, not
overtopping the capsule. Seta 10--15
mm. Capsule exserted, oval to
oblong-cylindrical, 1--2 mm; operculum obliquely long-rostrate, 0.5--1 mm; exostome
teeth yellowish, finely papillose; endostome yellowish, longer than exostome
teeth, finely papillose, trellis perfect. Calyptra 3--6 mm. Spores
12--14 \um. Rocks or
stones (occasionally tree bases, and roots) in and along brooks, wet
depressions, stream banks; low to high elevations (63--3444 m); Alta., B.C., Man.,
Nfld. and Labr., Ont., Que.; Alaska, Colo., Maine, Mich., Minn., N.H., N.Y.,
Utah, Vt., Wis., Wyo.; Europe; Asia (Siberia, China). Dichelyma
falcatum is the
largest species in the genus. Critical
features include strongly ranked, usually acute, lanceolate leaves that vary
from erect to somewhat falcate at the stem and branch tips; exserted
capsules; and perfect endostomial trellises. Although its leaves are about
the same length as those of the other species, they are much broader: D.
falcatum 0.7--1.4 mm wide; D. capillaceum, D. pallescens, D.
uncinatum 0.4--0.8 mm wide. Dichelyma pallescens is often confused
with D. falcatum, but that species usually
occurs on bark rather than rocks and boulders. It also has narrower leaves with
broader, frequently obtuse apices; immersed to emergent capsules; and imperfect
endostomial trellises. The leaves of D.
falcatum are sometimes long-excurrent, and this has caused it to be
confused with D. uncinatum. Both
species have exserted capsules with perfect endostomial trellises; D. uncinatum differs from D. falcatum in having leaves that are
more slender, and strongly secund to circinate at the stem and branch tips. 3. Dichelyma pallescens
Bruch & Schimper in Bruch, Schimper & Gümbel, Bryol. Eur. 5:
24.1846 Dichelyma obtusulum Kindberg; Neckera leucoclada Müller Hal., Syn. Musc. Frond. 2: 144. 1850 Plants slender to medium sized, to 10 cm
long, somewhat glossy, green, yellowish or yellow-brown. Axillary hairs 140--200 \um long, 3--6 cells, basal 1 cell
quadrate to subrectangular, brownish, upper 2--5 cells long cylindrical to
oblong, hyaline. Leaves weakly
three-ranked, lanceolate, subulate to acuminate, acute to obtuse, 3--4 mm
long;, margins plane, entire below, serrulate above; costa subpercurrent to
percurrent; medial leaf cells 100--140 x 5-8 x \um, alar cells firm-walled,
quadrate or rectangular, slightly enlarged. Perichaetial leaves up
to 7 mm long, overtopping the capsule. Setae
4--7 mm long. Operculum obliquely
long-rostrate, 0.5--1 mm long. Capsule
emergent, oval to oblong-cylindrical, 1--2 mm long. Exostome teeth reddish, finely papillose, at times perforated
along medial line. Endostome
reddish, longer than exostome teeth, finely papillose, trellis imperfect. Calyptra 3--4 mm long. Spores 10--15 \um. On tree (Acer, Alnus, Fraxinus, Populus) trunks and bushes (occasionally
on rocks) subject to inundation during times of high water; low to medium elevation
(40--426 m); N.B., Nfld and Labr. (Nfld.), Ont., Que.; Dichelyma
pallescens is a mostly corticolous species that differs from all other North
American Dichelyma species in often having broadly acute to obtuse
leaf apices. It is a medium-sized species that is occasionally confused with D.
falcatum. Dichelyma flacuatum is usually
saxicolous, has much broader leaves (0.7--1.4 vs.0.4--0.8 mm wide), exserted
capsules, and perfect endostomial trellises. Dichelyma capillaceum and D.
pallescens often occur in mixed collections; both have immersed to
laterally emergent capsules with imperfect endostomial trellises. Dichelyma capillaceum differs from D. pallescens in having setaceous leaf
apices and long excurrent costae. 4. Dichelyma uncinatum Mitten, J. Linn. Soc., Bot. 8: 44.
1864 Dichelyma cylindricarpum Plants slender, to 12 cm, green to yellowish green,
brownish at base; axillary hairs 180--220 \um, of 4--5 cells, basal cell
quadrate, brownish, distal 3--4 cells long-cylindrical, hyaline. Leaves weakly three-ranked,
linear-lanceolate, filiform-acuminate, 4--5 mm; margins plane; costa
long-excurrent, serrulate at apex; medial cells, 60--110 x 4--8 x \um; alar
cells firm-walled, quadrate or rectangular, not or slightly enlarged. Perichaetial leaves to 7 mm, sheathing
the setae, not or rarely overtopping the capsule. Seta 4--12(--20) mm. Capsule
emergent or shortly exserted, oblong-cylindric to cylindric, 1--3 mm; operculum
conic, 1--1.5 mm; exostome teeth spiculose-papillose; endostome yellowish brown
to orange-red, spiculose-papillose, trellis perfect. Calyptra 3--5 mm. Spores
10--17 \um. Tree trunks
and branches (Acer, Alnus, Populus, Quercus,
Salix, Toxicodendron), roots, shrubs (occasionally rocks), swamps, bottom
forests, flood plains, pond margins, frequently submerged at high water; low
to high elevation (6--1066 m); B.C., Ont.; Alaska, Calif., Idaho, Mont.,
Oreg., Wash., Wyo. Dichelyma
uncinatum is corticolous (rarely on rock), and differs from other Dichelyma species
in having strongly falcate to circinate leaves at tips of the stems and
branches. Dichelyma capillaceum is similar to D. uncinatum in
size, and both species have slender, linear-lanceolate leaves with setaceous
apices and long-excurrent costae. In D. capillaceum the stem and
branch tips have erect-spreading to flexuose-spreading
and somewhat longer (4--7 vs. 4--5 mm) leaves.
In addition D. capillaceum has immersed or laterally emergent
capsules and incomplete endostomial trellises. Dichelyma falcata has been confused with D. uncinatum because it sometimes has excurrent costae, and both
species have exserted capsules with perfect endostomial trellises. But, D.
falcatum, is usually saxicolous and has much broader leaves (0.7--1.4 vs.
0.4--0.8 mm wide) that are flexuose-spreading to falcate at the stem and
branch tips. The remarkable record of D.
uncinatum from southeastern |
