BFNA Title: Myurella
Author: D. H. Vitt 
Date: September 17, 2004
Edit Level: R Brum+
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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XX. MYURELLA Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 6: 39.  1853 * [referring to the smoothly cylindric, mouse-tail appearance of branches]

Dale H. Vitt

 

Plants thread-like.  Branches simple to irregularly branched, erect-ascending to creeping; paraphyllia absent.  Leaves imbricate and erect to wide-spreading and widely spaced, concave, ovate, blunt, and sometimes apiculate; margins erect, subentire to serrulate; laminal cells rhomboidal, firm-walled, nearly smooth to strongly 1-papillose abaxially; costa short, single, double, weak or almost absent; alar cells not differentiated.  Sexual condition dioicous.  Sporophytes rare. Capsule erect to nearly horizontal, cylindric, smooth; peristome double, well-developed. Calyptra cucullate.

 

Species 9 (3 in the flora);  worldwide except Antarctica .  Small, slender plants of calcareous rock shelves and calcareous moist soils, mostly in boreal and Arctic zones.

 

1.  Leaf cells with one, large stout papilla abaxially . . .  2. Myurella sibirica

1.  Leaf cells smooth or prorulose abaxially.  

2.  Leaves imbricate, erect, rounded-obtuse to occasionally short-apiculate . . . . . . . . . . . . . . . . . . . . . .1. Myurella julacea

2.  Leaves distant, wide-spreading, shortly acuminate-apiculate . . . 3. Myurella tenerrima

 

1. Myurella julacea (Schwägrichen) Schimper in P. Bruch, W. P. Schimper & W. Gümbel,  Bryol. Eur. 6: 41. 560.  1853

 

Leskea julacea Schwägrichen in J. A. Schultes, Reise Glockner 2: 363. 1804

 

Plants yellow-green.  Stem leaves crowded, imbricate, erect, about 0.3 mm, rounded to ovate, obtuse, occasionally with a tiny apiculus; margins serrulate to subentire; distal laminal cells faintly prorulose.

 

Calcareous habitats, including seepages, rock crevices, and fens;  frequent in boreal and Arctic areas, common in western montane areas with calcareous rocks; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Conn., Maine, Mass., Mich., Minn., Mont., N.Y., Vt., Wash., Wis., Wyo.; Europe; Asia.

 

This species is distinguished as the small, worm-like plants, yellow-green in color.  The leaves are concave and tightly overlap.  It is easily distinguished from the other two species of the genus by obtuse leaves that have at most a tiny apiculus. 

 

2. Myurella sibirica (J. K. A. Müller) Reimers, Hedwigia 75: 292.  1937

 

Hypnum sibiricum J. K. A. Müller, Syn. Musc. Frond. 2: 418. 1851; Myurella careyana Sullivant; M. sibirica var. tenella (Habeeb) H. A. Crum, Steere, L. E. Anderson

 

Plants glaucous-green.  Stem leaves distant, loosely erect to wide-spreading; about 0.4--0.6 mm, ovate, long-apiculate to slenderly acuminate; margins irregularly dentate to spinose-dentate; distal laminal cells strongly papillose, each cell with a single, high, central papilla.

 

Mesic, calcareous rock crevices; B.C., N.B., Nfld., N.W.T., N.S., Nunavut, Ont., Que., Yukon; Alaska, Ark., Ill., Ind., Iowa, Ky., Maine, Md., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., S.C., Tenn., Vt., Va., W.Va., Wis.; Europe; n Asia.

 

This species is not uncommon in the East, but becomes rare in northwestern North America. Small, slender, glaucous plants with widely spaced leaves and very large papillae distinguish this species.  The leaves end in a rather long, slender apiculus and the margins are distinctly and irregularly serrulate.  The large central papillae and strongly toothed leaf margins distinguish this species from the two other species of the genus. 

 

3. Myurella tenerrima (Bridel) Lindberg, Musci Scand. 37. 1879

 

Pterigynandrum tennerrimum Bridel, Mant. Musc. 132. 1819

 

Plants pale to yellow-green.  Stem leaves widely spaced, erect to spreading, 0.3--0.4 mm, rounded to ovate, acuminate to shortly apiculate, the apiculus ± recurved; margins serrulate; distal laminal cells faintly prorulose.

 

An Arctic and northern boreal species of moist calcareous habitats; infrequent in fens, rock crevices, and tundra meadows; Greenland; Alta., B.C., Man., Nfld., N.W.T., Nunavut, Ont., Que., Yukon; Alaska; Europe; n Asia; n Africa. 

 

This species is similar to M. julacea in color and general habit, but with widely spaced leaves that end in a well-developed, often recurved apiculus.  It differs from M. sibirica in features of the leaf papillae and margins.