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Nuttall's homalothecium moss

silken homalothecium moss

Habit Plants small to medium-sized, in dense tufts, light green when young, golden or brownish yellow with age. Plants medium-sized to large, in dense or loose tufts, light green to golden or brownish yellow.
Stem(s)

leaves erect-appressed, ± homomallous, triangular-lanceolate, 1–2(–2.5) × (0.2–)0.4–0.7(–0.8) mm;

base short-rounded, narrowly decurrent;

margins plane or often recurved in places, minutely serrulate to subentire, teeth in alar region small, conspicuous, recurved;

apex long-acuminate, acumen filiform, providing hyaline-villous aspect;

costa to 70–90% leaf length, often vanishing in plication, terminal spine sometimes present;

alar cells subquadrate, 6–7 µm wide, region of 6–9 × 5–8 cells, distinctly delimited, not reaching margins;

laminal cells linear-flexuose, 35–95 × 4–6 µm;

basal cell shape irregular, short, region in 2 rows, indistinctly delimited from more distal cells.

leaves erect-appressed, ± homomallous, triangular-lanceolate, (1.3–)1.8–2.4 × (0.4–)0.6–0.8 mm;

base short-rounded, narrowly decurrent;

margins plane or often recurved at places, serrulate, proximal teeth more prominent, often recurved;

apex acuminate or gradually tapered, acumen occasionally short-filiform, not providing hyaline-villous aspect;

costa to 60–80% leaf length, terminal spine absent, occasionally present;

alar cells ovate, 6–9 µm wide, region of 10–16 × 10–15 cells, moderately distinctly delimited;

laminal cells linear, 40–85 × 5–6 µm;

basal cells irregularly ovate, short, region in 1–3 rows, indistinctly delimited from distal cells.

Branch leaves

appressed when dry, spreading when moist, narrowly lanceolate, (0.5–)0.7–1.7 × (0.1–)0.2–0.4 mm;

margins plane or recurved at places, serrulate or serrate proximally, entire or minutely serrulate distally, teeth in alar region conspicuously recurved;

apex acuminate;

costa to 70–90% leaf length, disappearing in acumen, terminal spine sometimes present;

alar cells subquadrate, 6–7 µm wide, region small, distinctly delimited;

laminal cells linear-flexuose, 25–85 × 4–6 µm;

basal cells in 1 (or 2) rows;

distal cells smooth.

appressed to erect when dry, spreading when moist, narrowly lanceolate, 1–2 × 0.2–0.5 mm;

margins plane or recurved at places, serrulate or serrate proximally, entire or minutely serrulate distally;

apex acuminate;

costa to 60–85% leaf length, terminal spine sometimes present;

alar cells subquadrate or irregularly ovate, 7–10 µm wide, region small, of 2–5 cells along margins, indistinctly delimited;

laminal cells linear-flexuose, 40–90 × 4–7 µm;

basal cells in 1 (or 2) rows;

distal cells smooth.

Seta

0.7–1.5 cm, rough.

Sexual condition

phyllodioicous or dioicous.

phyllodioicous or dioicous.

Capsule

erect, cylindric, sometimes slightly curved, 2–2.5 mm;

annulus separating by fragments;

operculum long-conic;

peristome hygrocastique;

exostome teeth with long transitional zone;

endostome basal membrane high, segments as long as teeth, very narrow, cilia very short or absent.

erect, cylindric, straight or slightly curved, 2–3 mm;

annulus separating;

operculum long-conic, short-rostrate;

peristome hygrocastique;

exostome teeth papillose to base;

endostome basal membrane moderately high, segments as long as teeth, narrow, cilia very short.

Spores

dimorphic; 10–14 µm or 16–20 µm.

15–19 µm].

[seta 1–2 cm, rough.

Homalothecium nuttallii

Homalothecium sericeum

Habitat Epiphytic on trunks and branches of hardwood trees and Douglas fir, forests and open stands, especially Quercus garryana, rock, rotten logs Soil in grasslands, rock, rock faces, shrubs growing on rock outcrops
Elevation low to high elevations (0-1600 m) (low to high elevations (0-5200 ft)) low elevations (0 m) (low elevations (0 ft))
Distribution
from FNA
AK; CA; OR; WA; BC
[WildflowerSearch map]
from FNA
NF; w Eurasia; n Africa; Atlantic Islands
Discussion

A. J. Grout (1928–1940, vol. 3) reported Homalothecium nuttallii from Idaho and Montana, but H. Hofmann (1998) found that these specimens are H. nevadense. E. Lawton (1965) did not cite H. nuttalii for these states. The species can be recognized in the field by the relatively narrow, leafy branches. Also, the branch leaves are distally filiform and, when dry, look hyaline-villous, resembling species of Fabronia. Under the microscope, the recurved teeth of leaf margins allow immediate species identification. The branch leaves may be straight, homomallous, or falcate-secund; the small spores are smooth, the larger papillose.

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

The rather weak molecular differences of the North American Homalothecium sericeum from European material (S. Huttunen et al. 2008) and the limited distribution in Newfoundland suggest a rather recent migration of H. sericeum to North America. The closest stations are in Iceland, 2500 km from Newfoundland. Brachythecium laetum also has opaque basal cells, but it never develops recurved teeth along the leaf margins in the alar region.

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

Source FNA vol. 28, p. 441. FNA vol. 28, p. 443.
Parent taxa Brachytheciaceae > Homalothecium Brachytheciaceae > Homalothecium
Sibling taxa
H. aeneum, H. arenarium, H. aureum, H. californicum, H. fulgescens, H. megaptilum, H. nevadense, H. sericeum
H. aeneum, H. arenarium, H. aureum, H. californicum, H. fulgescens, H. megaptilum, H. nevadense, H. nuttallii
Synonyms Hypnum nuttallii Leskea sericea
Name authority (Wilson) A. Jaeger: Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876 – 1877: 310. (1878) (Hedwig) Schimper: in P. Bruch and W. P. Schimper, Bryol. Europ. 5: 93. (1851)
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