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BFNA | Family List | BFNA Vol. 1 | Dicranaceae | Dicranum

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

  • Dicranum fuscescens f. pallidiseta J. W. Bailey

    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 lacking. with a row of guide cells, stereid bands often present and well-developed in proximal part of leaf, lacking 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 lacking; 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) $$m. 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; sw Alta., s B.C.; s Alaska, n Idaho, w Mont., n Oreg., Wash.

    This is an endemic northwestern North American species that 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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