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FNA | Family List | FNA Vol. 27 | Dicranaceae | Dicranum

16. Dicranum pallidisetum (J. W. Bailey) Ireland, Bryologist. 68: 446. 1965.

Dicranum fuscescens forma pallidiseta J. W. Bailey in J. M. Holzinger, Musci Acroc. Bor.-Amer., no. 653. 1929

Plants in loose tufts, dark green to yellowish green, dull to glossy. Stems 1-6 cm, tomentose with white or reddish brown rhizoids. Leaves often secund, straight or nearly so, often crisped when dry, smooth, 4-8 × 0.5-1 mm, lanceolate, acute, tubulose to apex; margins entire below, serrulate ot serrate near apex; laminae 1-stratose or sometimes 2-stratose on distal margins; costa excurrent, 1/5-1/3 the width of the leaves at base, abaxially papillose or toothed from leaf middle to apex, abaxial ridges absent, with a row of guide cells, stereid bands often present and well-developed in proximal part of leaf, absent in distal 1/4-1/3 of leaf, cells above and below guide cells large and thin-walled; cell walls between lamina cells not or slightly bulging; leaf cells smooth or often strongly papillose in distal half of leaf; alar cells 2-stratose, differentiated, often extending to costa, abaxial ridges absent; proximal laminal cells linear to rectangular, with or without pits, (26-)58-95(-130) × (10-)12-14(-16) µm; distal laminal cells quadrate, rounded, irregularly angled or short-rectangular, not pitted, (10-)15-26(-38) × (8-)9-11(-12) µm. Sexual condition dioicous; male plants as large as female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing. Seta 1-2.5 cm, solitary or sometimes 2, rarely 3, per perichaetium, yellow, rarely reddish yellow or brown with age. Capsule 1.5-3.5 mm, arcuate, inclined, often with a small struma, strongly furrowed when dry, contracted below mouth, yellow or yellowish brown, rarely reddish yellow or brown with age; operculum 1.5-2.5 mm. Spores 14-20 µm.

Capsules mature in summer. Humus or soil over rock, rarely rotting logs or decayed wood; 500-2000 m; Alta., B.C.; Alaska, Idaho, Mont., Oreg., Wash.

Dicranum pallidisetum has often been confused with D. fuscescens, being considered a form of it for many years (R. R. Ireland 1966). Unlike that species, which often occurs at low altitudes below 800 m, D. pallidisetum occurs predominately at high elevations, 800-2000 m, rarely being found as low as 500 m. It is distinguished from D. fuscescens by its tubulose leaves, usually 1-stratose or rarely 2-stratose on the margins, by its costa cross section that shows no stereid bands in the distal 1/3 of the leaf, and by its yellow or yellow-brown capsules that are sometimes 2-3 per perichaetium. In contrast, D. fuscescens has leaves keeled above, usually 2-stratose on both margins, rarely 1-stratose on one margin, stereid bands present throughout the leaf and dark brown to reddish brown capsules that are solitary or rarely 2 per perichaetium.


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