Sarmentypnum exannulatum
Sarmentypnum
leaves ovate or ovate-triangular, gradually narrowed to apex, falcate or strongly so, sometimes straight, concave;
base not decurrent;
margins distinctly denticulate proximally, distally, or both;
apex acuminate, sometimes furrowed but not strongly so;
costa ending 3/5 to nearly entire leaf length;
alar region from margins to costa or nearly so;
marginal cells at widest part of leaf often differentiated from medial cells.
leaves triangular to ovate or narrowly ovate, gradually or abruptly narrowed to apex, straight or falcate, concave or strongly concave, not or indistinctly plicate;
base not or hardly decurrent (broadly long-decurrent in S. tundrae);
margins entire or denticulate;
apex acuminate, obtuse, or broadly rounded and usually apiculate;
costa single, 3/5 leaf length to long-excurrent;
alar cells differentiated, many, quadrate or short- to long-rectangular, inflated or strongly inflated, hyaline, walls thin, or, especially near costa or when old, red or brown and incrassate, region distinctly delimited, large, transversely triangular, from margins ± to costa;
medial laminal cell walls incrassate or thin, porose or not.
dioicous;
inner perichaetial leaves not plicate;
vaginula naked.
with annulus not separating;
exostome external surface reticulate proximally, margins dentate distally.
11–24 µm.
Sarmentypnum exannulatum
Sarmentypnum
Sarmentypnum exannulatum is one of the most frequent wetland species, with leaves that narrow gradually to the apex and are gradually curved throughout. The marginal laminal cells in the widest part of the stem leaves are often distinctly rectangular, distinctly widened, or both; this feature is never as pronounced in other species of Sarmentypnum as in S. exannulatum. However, because this feature is rather variable it should be used with caution when identifying material. Warnstorfia fluitans and W. pseudostraminea differ from S. exannulatum in being autoicous, having mainly narrowly triangular to lanceolate pseudoparaphyllia, hardly ever with pure red pigments, and with more weakly differentiated alar regions. The alar regions in W. fluitans usually reach less far distally in the leaf than in S. exannulatum, whereas those in W. pseudostraminea often form ovate regions together with the supra-alar cells. Phenotypes of S. exannulatum, found in springs, with inflated alar cells in more or less one row along the leaf base have been called W. exannulata var. purpurascens. However, transitions between these phenotypes and those from other habitats exist, and if the different phenotypes are cultivated together, the resulting plants cannot be separated (based on north European material).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 7 (5 in the flora).
The leaves of Sarmentypnum are either moderately curved to straight and gradually narrowed to the apex, or straight and suddenly narrowed to a usually apiculate apex. Red pigments are frequent in several species, and the leaves are nondecurrent in all except S. tundrae. The alar regions are transversely triangular and consist of inflated and (at least when young) usually hyaline cells. Except for S. tundrae, species of Sarmentypnum occur in intermediately mineral-rich fens and nutrient-poor habitats. Sarmentypnum collections with falcate leaves and lacking sporophytes or red pigment are frequently confused with falcate-leaved species with transversely triangular alar regions in the Drepanocladus aduncus complex. The frequently present rhizoid initials occurring close to leaf apices in all species of Sarmentypnum except S. trichophyllum differentiate these from species of Drepanocladus, which lack such initials.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stem leaf bases broadly long-decurrent; plants never red. | S. tundrae |
1. Stem leaf bases not or hardly decurrent; plants often with red secondary pigment | → 2 |
2. Leaf costae excurrent; branch and often shoot apices pencil-like; axillary hair distal cells 2-7, brown when young. | S. trichophyllum |
2. Leaf costae not excurrent; branch and shoot apices not pencil-like; axillary hair distal cells 1-4(-5), hyaline when young | → 3 |
3. Stem leaves oblong, ovate, or narrowly ovate, ± abruptly narrowed to apex; apices rounded- or acute-apiculate. | S. sarmentosum |
3. Stem leaves ovate or ovate-triangular, gradually narrowed to apex; apices acuminate or sometimes blunt | → 4 |
4. Stem leaves falcate or straight; margins distinctly denticulate proximally, distally, or both; marginal cells at widest part of leaf often differentiated from medial cells; leaves concave; apices sometimes furrowed but not strongly so. | S. exannulatum |
4. Stem leaves straight or almost so; margins entire or in part finely, obtusely denticulate; marginal cells at widest part of leaf similar to medial cells or rarely slightly differentiated; leaves strongly concave; apices deeply furrowed. | S. pseudosarmentosum |
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Flora NW
MD Biodiversity
MI Flora
MN Wildflowers
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