Dicranum majus

Turner

Muscol. Hibern. Spic., 59. 1804,.

Treatment appears in FNA Volume 27. Treatment on page 405. Mentioned on page 399, 403.

Plants in loose tufts, green to light green, glossy to somewhat dull. Stems 3–16 cm, naked or with a few whitish rhizoids, rarely moderately tomentose, rhizoids (micronemata) in rows above each leaf. Leaves somewhat sparse, falcate-secund or erect-patent, flexuose or straight, little changed when dry, usually smooth, (6–) 8–11.5 (–15) × 1–2 mm, concave proximally, tubulose above, from a lanceolate to ovatelanceolate base, gradually narrowed to a long, falcate-secund or straight, acute apex; margins serrate in the distal half, sometimes slightly serrulate above to almost entire; laminae 1-stratose or with few 2-stratose regions on or near the margins; costa percurrent to shortly excurrent, 1/12–1/7 the width of the leaves at base, toothed distally or serrulate to nearly smooth on abaxial surface, with a double row of guide cells that sometimes interrupted, two stereid bands extending to apex, adaxial epidermal layer of cells with some cells differentiated, the abaxial layer completely differentiated; cell-walls between lamina cells not bulging; leaf cells smooth or abaxially prorate or toothed above; alar cells 2-stratose or multistratose, well-differentiated, not extending to costa; proximal laminal cells elongate, pitted, (42–) 71–112 (–140) × (5–) 9–10 (–15) µm; distal laminal cells shorter, linear to oval, pitted, (42–) 47–61 (–99) × (7–) 10–11 (–17) µm. Sexual condition pseudomonoicous; dwarf males among rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing. Seta 2.5–5 cm, aggregate, 2–5 per perichaetium, rarely solitary, yellow to light-brown. Capsule 2–3.5 mm, arcuate, inclined to horizontal, smooth to faintly striate when dry, dark-brown or yellowish-brown; operculum 2–3 mm. Spores 14–19 µm.

Discussion

Varieties ca. 12 (2 in the flora).

Dicranum majus is the only North American species of the genus with a double row of guide cells. It is a distinctive species with oceanic tendencies and in North America it commonly grows in northern coastal localities on both sides of the continent, occasionally occurring inland in very moist habitats.

Selected References

None.

Key

1 Leaves falcate-secund, 8-15 mm; margins serrate in the distal half; costa toothed distally on abaxial surface, with a double row of guide cells. Dicranum majus var. majus
1 Leaves erect-patent, 6-8 mm; margins slightly serrulate above to almost entire; costa serrulate to nearly smooth distally on abaxial surface, with an interrupted double row of guide cells Dicranum majus var. orthophyllum
... more about "Dicranum majus"
persistent +  and deciduous +
differentiated +
falcate-secund +
1.15 cm11.5 mm <br />0.0115 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
straight +
0.8 cm8 mm <br />0.008 m <br /> (1.15 cm11.5 mm <br />0.0115 m <br />) +
1mm +  and 2mm +
Robert R. Ireland Jr. +
Turner +
short to long +
differentiated +
1.15 cm11.5 mm <br />0.0115 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (1.15 cm11.5 mm <br />0.0115 m <br />) +
concave +, ovatelanceolate +  and lanceolate +
1mm +  and 2mm +
microphyllous +
pseudomonoicous +, dioicous +, autoicous +  and sexual +
flagelliform +  and terete +
reproduction +  and asexual +
cucullate +
yellowish-brown +  and dark-brown +
arcuate +  and straight +
inclined +  and horizontal +
smooth +  and faintly striate +
cylindric +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
multistratose +  and 2-stratose +
generally orange +  and brown +
specialized +
papillose +  and mammillose +
pseudomonoicous +, dioicous +  and sexual +
inflated +
well-differentiated +  and differentiated +
serrulate;nearly smooth +
1/12 +  and 1/7 +
toothed +
toothed +
pseudomonoicous +  and sexual +
spreading +, erect-patent +  and erect-appressed +
smooth +  and rugose +
nw +, ne North America +, Europe +  and Asia +
reddish-brown +  and pitted-striolate +
with few 2-stratose regions +  and 1-stratose +
enlarged +
falcate-secund +
papillose +, mammillose +, nonpitted +  and pitted +
straight +  and flexuose +
acuminate +, ovate +  and lanceolate +
serrulate +  and serrate +
arcuate +  and straight +
long-rostrate +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
nonpitted +  and pitted +
toothed +  and forked +
short-acuminate +, concave +  and ovate +
pitted-striolate +
16 +  and single +
papillose +  and striolate +
undifferentiated +
Muscol. Hibern. Spic., +
smooth +  and papillose +
1 +  and 2 +
interrupted +
well-developed +
yellow;light-brown +
flexuose +  and straight +
2 +  and 5 +
elongate +
2.5 cm25 mm <br />0.025 m <br /> (5 cm50 mm <br />0.05 m <br />) +
1/3 +  and 1/2 +
spherical +
with a few whitish rhizoids;naked +
3 cm30 mm <br />0.03 m <br /> (16 cm160 mm <br />0.16 m <br />) +
superficial +
Dicranum majus +
Dicranum +
species +
deciduous +
lanceolate +
green +  and light green +
dull +  and glossy to somewhat +