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isopterygium moss

isopterygium moss

Habit Plants small, in thin to dense mats, whitish to yellowish. Plants small to medium-sized, in thin to dense mats, whitish, yellowish, or green, glossy.
Stem(s)

to 2(–5) cm, 0.5–1.5(–3) mm wide.

and branch leaves similar, erect-spreading to squarrose, ovate or lanceolate, not plicate;

base not decurrent or rarely 1 or 2 cells decurrent;

margins plane to erect, serrulate to entire proximally, serrate to serrulate distally, or rarely entire throughout;

apex acuminate;

costa double and short or sometimes ecostate;

alar cells usually clearly differentiated, quadrate to rectangular, rarely transversely elongate;

laminal cells smooth.

Leaves

erect-spreading, not or slightly wrinkled when dry, ovate to lanceolate, 0.7–1.8 × 0.2–0.6 mm;

margins plane, serrulate to entire proximally, serrate to serrulate distally, rarely entire throughout;

alar cells short-rectangular, quadrate, or transversely elongate, 12–38 × 10–20 µm, region small;

medial laminal cells often flexuose, linear-fusiform, 52–151 × 5–8 µm.

Seta

yellow to reddish brown, 0.5–1.5 cm.

yellow, brown, or reddish brown.

Sexual condition

autoicous [rarely dioicous];

perichaetia at base of stems, leaves oblong-lanceolate, apex gradually acuminate.

Capsule

cernuous, rarely erect, light brown to orange-brown, 0.5–2 mm;

operculum conic-apiculate to obliquely short-rostrate.

inclined to cernuous, sometimes erect, ovoid to ellipsoid, straight or arcuate when mature, usually contracted below mouth and sometimes wrinkled at neck when dry;

annulus absent;

operculum conic to short-rostrate;

peristome double;

exostome teeth with external surface cross striolate proximally, papillose distally;

endostome basal membrane high to low, segments keeled, cilia shorter than segments, in groups of 1–3, sometimes absent.

Calyptra

naked.

Spores

9–14 µm.

spheric to ovoid, smooth or minutely papillose.

Specialized

asexual reproduction sometimes present as filaments on stems, multicellular, green or brown, simple or branched, often more than 0.5 mm, cells papillose.

asexual reproduction sometimes present as filamentous, multicellular, branched brood bodies on stems and branches, cells papillose.

Isopterygium tenerum

Isopterygium

Phenology Spores 9-14 µm, mature spring–summer.
Habitat Dry wooded regions, swamps, wet roadside ditches, base of trees, rotten logs, stumps, sandy soil, sedimentary rock
Elevation low to moderate elevations (0-400 m) [low to moderate elevations (0-1300 ft)]
Discussion

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 and are therefore included in the synonymy. A biometric analysis by P. L. Redfearn (1956) on the stem leaf variation reached a similar conclusion.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 120–140 (2 in the flora).

Isopterygium occurs predominately in terrestrial habitats at low elevations in the subtropics and tropics. Many of the names in this genus will undoubtedly prove synonymous with those of other taxa after revision. Plants of this genus have complanate-foliate stems with small, thick-walled cortical cells and larger, thinner walled inner cells; the smooth rhizoids arise on the ventral surfaces of stems and branches just below the junctures of leaves; and the axillary hairs have one short-rectangular basal cell and one elongate apical cell. The leaves are crowded, imbricate, often asymmetric, and flat or somewhat concave, sometimes with pitted basal laminal cells. The perigonia are scattered along the stems; the setae are usually twisted; the capsules are smooth; and the exostome teeth are bordered and internally trabeculate.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Distribution
from FNA
AL; AR; DC; DE; FL; GA; KY; LA; MA; MD; MO; MS; NC; NJ; NY; OH; SC; TN; TX; VA; NS; Mexico; Central America; South America; West Indies; s Europe (Italy)
[WildflowerSearch map]
North America; Mexico; Central America; South America; West Indies; s Europe (Italy); Asia; Africa; Pacific Islands; Australia
Parent taxa Hypnaceae > Isopterygium Hypnaceae
Sibling taxa
I. tenerifolium
Subordinate taxa
I. tenerifolium, I. tenerum
Key
1.Plants small; stems seldom larger than 2 cm; leaves 0.7-1.8 × 0.2-0.6 mm, not or slightly wrinkled when dry; setae 0.5-1.5 cm.I. tenerum
1.Plants medium-sized; stems 2-4 cm; leaves 1-1.5 × 0.4-0.7 mm, usually wrinkled and contorted when dry; setae 2-3 cm.I. tenerifolium
Synonyms Hypnum tenerum, H. albulum, H. chapmanii, H. fulvum, H. micans, I. drummondii, I. fulvum, I. groutii, I. micans, I. micans var. latifolium, I. micans var. minus, Isothecium tenerum, Plagiothecium fulvum, P. groutii, P. micans, P. micans var. fulvum, Rhaphidostegium ludovicianum, Rhynchostegium micans
Name authority (Swartz) Mitten: J. Linn. Soc., Bot. 12: 499. (1869) Mitten: J. Linn. Soc., Bot. 12: 21, 497. (1869)
Source Flora of North America vol. 28, p. 553. Flora of North America vol. 28, p. 552.
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