Aulacomnium palustre
Aulacomnium acuminatum
aulacomnium moss, glow moss, rib bog moss
acutetip aulacomnium moss, point groove moss
yellow, yellowish green, or yellowish brown;
cross section pentagonal, cortical cells in 4–6 irregular layers, outer medulla cells thicker walled than inner, central strand conspicuous, sometimes degraded;
rhizoids between leaves throughout plants, conspicuous when dry or moist, or visible among leaves at base of plants.
yellow or light brown;
cross section pentagonal, cortical cells in 4–5 layers, medulla cell walls thick or thin, central strand well developed;
rhizoids in groups along stem, hidden by leaves.
distant and not covering rhizoids, or imbricate and rhizoids mostly hidden, undulate, twisted or straight when dry, erect-spreading when moist, broadly to narrowly lanceolate, widest at base, often concave;
base not rounded to insertion;
margins revolute usually one time, sometimes more, in proximal 2/3, irregularly serrulate at apex;
apex acute, acuminate, or narrowed, rounded, and somewhat cucullate;
costa flexuose;
laminal cells rounded quadrate, short-rectangular, or elliptic, papillae large;
basal cells often 2-stratose at insertion, walls brown.
strongly imbricate, not twisted when dry, erect or imbricate when moist, linear-lanceolate to oblong-lanceolate, widest mid leaf, weakly concave;
base not rounded, narrowed to insertion, sometimes slightly auriculate;
margins prominently revolute 1.5–2 times nearly to apex, entire;
apex gradually acuminate to slender-acute, usually long-attenuate in youngest leaves;
costa flexuose distally;
laminal cells isodiametric to elongate, papillae blunt;
basal cells 2-stratose, brown.
3–5 cm.
1.5–2 cm.
inclined to horizontal, 3–4 mm;
operculum short-rostrate, rostrum blunt;
endostome cilia nodose.
horizontal or slightly curved, 3 mm;
operculum short-conic, rostrum blunt;
endostome cilia weakly nodulose.
10–15 µm, smooth.
10–13 µm, slightly papillose.
asexual reproduction by bullet- or spearpoint-shaped propagula, flat at attachment, in terminal cluster.
asexual reproduction absent.
as terminal discoid splash platforms;
paraphyses of 8–12 cells.
as terminal discoid splash platforms;
paraphyses of 5–8 cells.
with paraphyses absent.
with paraphyses absent.
Aulacomnium palustre
Aulacomnium acuminatum
Aulacomnium palustre is essentially a Northern Hemisphere moss, widespread in North America, but not necessarily common throughout its range; it may be introduced in New Zealand. Numerous varieties and forms have been proposed and sometimes recognized to accommodate the range of morphological variation present in this moss (G. Sayre 1935; W. Kabiersch 1937). None of these infraspecific concepts are adopted here in the absence of thorough studies employing modern techniques. A distinctive alpine expression (var. imbricatum Bruch & Schimper) has been recognized in Colorado and elsewhere (W. A. Weber and R. C. Wittmann 2007). In such plants, the leaves cover most of the rhizoids but are narrowly lanceolate and widest near the base; this is also true in lowland expressions of A. palustre, where some populations can also have the narrowly rounded leaf apices of var. imbricatum. The leaves of this species are weakly plicate, and the costa surface cells are large and hyaline. The basal laminal cells of the inner perigonial leaves are large and smooth; the 4 or 5 distal cells are short and wider than the longer, more proximal cells. The perichaetia are in the form of splash cups.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Aulacomnium acuminatum has an interrupted circumarctic distribution: in North America from the northern edge of the tree line (under white and/or black spruce), throughout the Canadian Arctic Islands, with occurrences southward in adjacent alpine tundra, and disjunct north of Lake Superior in Ontario. The leaves of this species are sometimes curved, and the costae are buttressed at the base. The basal laminal cells of the inner perigonial leaves are large with walls evenly thickened; the proximal cells are long and narrow; the medial distal cells are short and wide. The innermost perigonial leaves are deltoid and as long as the paraphyses. The perichaetia have subfloral innovations, large outer leaves, and inner leaves with margins weakly toothed in the long-attenuate apex.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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