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BFNA Title: Isopterygium |
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Isopterygium -
Hypnaceae X.
ISOPTERYGIUM Mitten, J. Linn. Soc. Bot. 12: 21. 1869 * [Greek iso, equal, and pteron, winged] Robert R. Ireland Plants small to medium-sized, in thin to
dense, light- to yellowish-green glossy mats. Stems 4--5 cm, creeping, simple or sparingly and
irregularly branched, cortical cells small and thick-walled in cross section,
surrounding larger, thinner walled cells, central strand usually absent;
rhizoids smooth, on ventral surface of stems and branches just below juncture
of leaves; axillary hairs with one brownish short-rectangular cell and one
hyaline elongate apical cell; filamentous pseudoparaphyllia present, of 3--6
cells in 1 row or rarely with 2 rows at base. Leaves of stems and branches similar, rigid or flaccid,
crowded and imbricate to remote, erect-spreading or squarrose, commonly
complanate-foliate, sometimes wrinkled and contorted when dry, smooth, flat
or somewhat concave, symmetric or asymmetric, nondecurrent or rarely with
1--2 cells decurrent, ovate or lanceolate, acute to acuminate; margins plane
to erect, sometimes recurved at base, serrulate above the middle, mostly
entire below, sometimes entire throughout; costa short and double, sometimes
lacking; cells often flexuose, thin to firm-walled, linear-fusiform, smooth,
with walls not pitted or occasionally those of basal cells pitted; alar cells
usually clearly differentiated, quadrate to rectangular, rarely transversely
elongate. Specialized asexual
reproduction sometimes present on stems and branches, of uniseriate,
often branched, filamentous, multicellular bodies with papillose cells. Sexual condition autoicous or
rarely dioicous; perigonia scattered along stems; perichaetia at base of
stems, leaves oblong-lanceolate, gradually acuminate, margins plane. Seta solitary, yellow, brown or
reddish brown, 0.5--3 cm, usually twisted, straight to curved, smooth. Capsule inclined to cernuous,
sometimes erect, straight or arcuate when mature, brown to red-brown,
cylindric, ovoid or ellipsoid, smooth, usually contracted below mouth and
sometimes wrinkled at neck when dry; operculum conic to short-rostrate,
shorter than urn; annulus lacking; peristome double, exostome teeth
cross-striolate below, papillose above, bordered, trabeculate at back;
endostome with high to low basal membrane, segments keeled, cilia shorter than
segments, in groups of 1--3, sometimes lacking. Calyptra cucullate, smooth, naked. Spores spherical to ovoid, smooth
or minutely papillose. Species
120--140 (2 in the flora) but many will undoubtedly be synonymous with other
taxa after a worldwide revision; North America, Mexico, West Indies, Central
America, South America, Europe (Italy), Asia, Africa, Pacific Islands,
Australia. Plants of this
genus occur predominately in terrestrial habitats at low elevations in the
subtropics and tropics. SELECTED
REFERENCES Ireland, R. R. 1969.
A taxonomic revision of the genus Plagiothecium for North
America, north of Mexico. Natl. Mus.
of Canada, Natl. Mus. of Natural Sci., Publ. in Bot., No. 1: 1--118. Ireland, R. R. 1992. The moss genus Isopterygium
(Hypnaceae) in Latin America.
Tropical Bryology 6: 111--132.
Iwatsuki, Z. 1970. A revision of Plagiothecium and its
related genera from Japan and her adjacent areas, I. J. Hattori Bot. Lab. 33: 331--380. Iwatsuki, Z. 1987. Notes on Isopterygium
Mitt. (Plagiotheciaceae). J.
Hattori Bot. Lab. 63: 445--451.
Iwatsuki, Z. and M. R. Crosby.
1979. Lectotypification of the
genus Isopterygjum Mitt. J.
Hattori Bot. Lab. 45: 389--393.
Redfearn, P. L., Jr.
1956. Biometric analysis of
the stem leaf variation of the Plagiothecium micans complex in
southeastern United States.
Bryologist 59(4): 256--262. 1.
Plants small, stems seldom over 2 cm; leaves 0.7--1.2 × 0.2--0.6 mm, smooth or nearly so when dry; setae usually
0.5--1.5 cm . . . . 1. Isopterygium
tenerum 1.
Plants medium-sized, stems often 2--4 cm; leaves 1--1.5 × 0.4--0.7 mm, usually wrinkled and contorted when dry;
setae 2--3 cm . . . . 2. Isopterygium tenerifolium 1. Isopterygium tenerum (Swartz) Mitten, J. Linn. Soc. Bot. 12:
499. 1869 Hypnum
tenerum Swartz, Fl.
Ind. Occ. 3: 1817. 1806; H. albulum
J. K. A. Müller; H. chapmanii Duby; H. fulvum Hooker
& Wilson; H. micans Swartz; Isopterygium drummondii
H. A. Crum, Steere & L.E. Anderson; I. fulvum (A. Jaeger)
Kindberg; I. groutii (Cardot & Thériot ) Grout; I. micans
(Swartz) Kindberg; I. micans var. latifolium (Grout)
Schornherst; I. micans var. minus (Grout) H.A. Crum
& L.E. Anderson; Isothecium tenerum (Swartz) Bridel; Plagiothecium
fulvum A. Jaeger; P. groutii Cardot & Thériot; P.
micans (Swartz) Paris; P. micans var. fulvum (A.
Jaeger) Paris; Rhaphidostegium ludovicianum Renauld & Cardot; Rhynchostegium
micans (Swartz) Austin Plants in thin to dense mats, whitish- to
yellowish-green. Stems to 50
mm × 0.5--1.5(--3) mm, prostrate. Leaves close, complanate,
erect-spreading, often secund at tips, smooth, 0.7--1.8 × 0.2--0.6 mm, ovate to lanceolate, often asymmetric,
acuminate; margins plane, serrate to serrulate above leaf middle, serrulate
to entire below, rarely entire throughout; median cells 52--151 × 5--8 µm; alar cells short-rectangular to quadrate or
transversely elongate, in small groups, 12--38 ×
10--20 µm. Specialized asexual
reproduction sometimes present as filaments on stems, multicellular, simple
or branched, often more than 0.5 mm, green or brown. Sexual condition autoicous. Seta
yellow to reddish brown, 0.5--1.5 cm.
Capsule light brown to orange-brown, cernuous, rarely erect,
arcuate of sometimes straight, 0.5--2 ×
0.2--0.5 mm, ovoid to ellipsoid, usually strongly contracted below the mouth
when dry; operculum conic-apiculate to obliquely short-rostrate, 0.2--0.4
mm. Spores 9--14 µm. Capsules
mature spring--summer. Dry wooded
regions, swamps and wet roadside ditches, rotten logs, stumps, bases of
trees, sandy soil; rarely on sedimentary rock; 0--360 m; N.S.; Ala., Ark.,
Del., D.C., Fla., Ga., Ky., La., Md., Mass., Miss., Mo., N.J., N.Y., N.C.,
S.C., Tenn., Tex., Va.; Mexico; West Indies; Central America; South America;
Europe (Italy). Isopterygium
tenerum is common in
Florida and the Gulf Coast, becoming infrequent northward, occurring in
scattered localities to southern New York and disjunct to southern Nova
Scotia. The species is extremely variable and several varieties have been described
from North American plants. These
varieties, based on leaf shape and length, are believed to be environmental
forms that are not worth formal recognition and are therefore included in the
synonomy of I. tenerum.
P. L. Redfearn (1956), who did a biometric analysis on the stem leaf
variation, reached a similar conclusion.
Isopterygium tenerum in its typical form is best distinguished
by the usually complanate, small plants with stems 10--20 × 0.5--1.5 mm, filamentous pseudoparaphyllia, leaves ovate-lanceolate,
asymmetric, acuminate, close, erect-spreading, 0.7--1.8 mm, alar cells in
small groups of short-rectangular to quadrate or transversely elongate cells,
asexual reproductive bodies sometimes present on stems, filamentous,
multicellular, the cells papillose, setae 0.5--1.5 cm, and capsules ovoid to
ellipsoid, inclined to horizontal, usually strongly contracted below the
mouth when dry, 0.5--2.0 mm. 2. Isopterygium tenerifolium Mitten, J. Linn. Soc. Bot. 12:
499. 1869 Plants in thin, loose mats, yellow-green to
green. Stems to 40 × 2--3 mm, prostrate.
Leaves close, complanate, wide-spreading to squarrose, smooth,
usually wrinkled and contorted when dry, 1--1.5 × 0.4--0.7 mm, ovate-lanceolate to ovate, often curved and
asymmetric, acuminate; margins plane to erect throughout, serrate to
serrulate distally, serrulate proximally; median cells 71--141 × 5--7 µm; alar cells short-rectangular to quadrate, in
small groups with 1--2 cells on margins, 19--33 × 9--19 µm. Specialized
asexual reproduction lacking. Sexual
condition autoicous. [Seta brown
to reddish brown, 2--3 cm. Capsule
light brown to reddish brown, horizontal to pendulous, sometimes nearly
erect, 1--1.5 mm, ovoid to ellipsoid, contracted below the mouth when dry;
operculum obliquely short-rostrate. Spores
9--14 µm.] Capsules
mature apparently fall (fully developed sporophytes not seen in the flora
region). Low sandstone bluffs along river; altitude unreported; Miss.;
Mexico; West Indies; Central America; South America. Isopterygium
tenerifolium is known
from only one recent collection from Mississippi (Lauderdale Co., E shore of
Chunky R. at Stukey Bridge, ca. 32° 15'
N, 88° 52' W, 30 Sept. 1992, Buck 22129
CANM, NY). The species is
morphologically close to I. tenerum, differing by the somewhat
larger plants, stems often 2--4 cm, leaves 1--1.5 mm and usually wrinkled and
contorted when dry, and seta 2--3 cm.
The collection in CANM contains only one plant with an undeveloped sporophyte
that has a seta of 2 cm. The species
should be searched for elsewhere in the Gulf Coastal Region where other
populations likely occur. |
