BFNA Title: Warnstorfia
Author: L. Hedenäs 
Date: January 31, 2008
Edit Level: R
Version: 3

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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Revised Jan. 29, 2008 by L. H.


xxx. WARNSTORFIA Loeske, Verh. Bot. Ver. Prov. Brandenburg, 49 (Abh.): 63. 1907 * [For C. F. E. Warnstorf, German teacher and botanist, 1837--1921]

L. Hedenäs


Plants medium-sized, green, yellow-green, brownish, red-brown, very rarely with clear red colors. Stem sparsely to richly radially branched, with central strand and without hyalodermis, cells inside cortex thin-walled; outer pseudoparaphyllia narrow, triangular to lanceolate, occasional one broadly triangular; rhizoids or rhizoid initials at various points on the leaves, or on scattered points or in rows on the stem; axillary hairs with 1--4 distal hyaline cells. Stem leaves straight or falcate, triangular to ovate, gradually narrowed to a long-acuminate, acuminate, acute, or blunt apex, not plicate, concave; margin entire, sinuous or denticulate; costa single, ending 60--80% way up leaf; median lamina cells incrassate or thin-walled, porose or not; alar cells quadrate or shortly to long-rectangular, hyaline and thin-walled, inflated, in transversely triangular, narrowly transversely triangular or almost quadrate group, somewhat indistinctly delimited from surrounding cells, not or shortly decurrent. Sexual condition autoicous. Inner perichaetial leaves not plicate; vaginula naked. Capsule curved and ± horizontal; annulus not separating; exostome reticulate on lower outside, margin dentate distally. Spores 12.5--31 \um.


Species 2--3 (2 in the flora): nearly worldwide.


The genus Warnstorfia consists of autoicous species with leaves gradually curved to straight and gradually narrowed to the apex. Clear red colors occur very rarely in very exposed situations, and the leaves are not decurrent. The alar groups are transversely triangular or isodiametric, and consist of inflated, and (at least when young) usually hyaline cells. Warnstorfia species typically occur in mineral-poor fens, W. fluitans sometimes also in bogs. Although the species are mostly found in nutrient-poor habitats, W. fluitans, natural habitats of which are mostly poor or very poor in nutrients, can stand considerable nutrient-enrichment as evidenced by polluted localities in Europe. Warnstorfia plants with falcate leaves and lacking sporophytes, or perichaetia and perigonia, can be confused with similar species of Sarmentypnum. The latter, however, frequently develop red colors, have more sharply delimited transversely triangular alar groups, and are dioicous. In addition, Sarmentypnum species are mostly found in intermediately mineral-rich rather than mineral-poor situations.


SELECTED REFERENCES Hedenäs, L. 1993. A generic revision of the Warnstorfia-Calliergon group. J. Bryol. 17: 447--479. Hedenäs, L. 2006. Additional insights into the phylogeny of Calliergon, Loeskypnum, Straminergon, and Warnstorfia (Bryophyta: Calliergonaceae). J. Hattori Bot. Lab. 100: 125--134. Janssens, J. A. 1983. Past and extant distribution of Drepanocladus in North America, with notes on the differentiation of fossil fragments. J. Hattori Bot. Lab. 54: 251--298. Wynne, F. E. 1944. Studies in Drepanocladus. IV. Taxonomy. Bryologist 47: 147--189. Wynne, F. E. 1945. Studies in Calliergon and related genera. Bryologist 48: 131--155.


1. Alar cells forming a transversely triangular group; supra-alar cells rather small and not forming a group together with the alar cells; stem leaf apex usually not incurved................ 1. Warnstorfia fluitans

1. Alar cells forming an isodiametric or, more rarely, transversely triangular group; supra-alar cells large and together with alar cells often forming an ovate or rectangular group along lower leaf margin; stem leaf apex often incurved............. 2. Warnstorfia pseudostraminea


1. Warnstorfia fluitans (Hedwig) Loeske in E. Nitardy, Hedwigia 46: VI. 1907


Hypnum fluitans Hedwig, Sp. Musc. 296. 1801; Drepanocladus fluitans (Hedwig) Warnstorf; D. berggrenii (Lange & C. E. O. Jensen) G. Roth; D. fluitans var. falcatus (C. E. O. Jensen) G. Roth; Warnstorfia fluitans var. falcata (C. E. O. Jensen) H. A. Crum & L. E. Anderson; D. fluitans var. setiformis (Renauld) Mönkemeyer; D. fluitans var. uncatus H. A. Crum, Steere, & L. E. Anderson


Plants medium-sized, green, yellow-green or brownish to brown-red (clear red rarely seen in extremely exposed habitats); axillary hairs with 1--4-celled distal portion. Stem leaves falcate or sometimes straight, narrowly ovate to triangular-ovate and gradually narrowed to acuminate apex, concave or slightly so; margins denticulate, sometimes only in part or indistinctly so; costa ending at mid-leaf or to 80% distally in leaf (occasionally shorter or double); alar cells usually indistinctly delimited transverse, narrowly triangular group more or less reaching costa, supra-alar cells weakly differentiated.


Warnstorfia fluitans is recognized by its somewhat indistinctly delimited transverse, ± narrowly triangular alar groups in the stem leaves, and by being autoicous. Warnstorfia pseudostraminea has alar groups that are sometimes transversely triangular (though more broadly so than in W. fluitans), but in some or most leaves, the alar and the large supra-alar cells together form an oval or rectangular group along the proximal leaf margins. Warnstorfia pseudostraminea has usually ± straight to slightly falcate stem leaves, often with obtuse leaf apices having short cells, and the leaf apex is commonly hooked. However, neither of the last mentioned features are constant in W. pseudostraminea, and occasional (rare) specimens of W. fluitans have the same character states.


Mineral-poor and acid, but sometimes nutrient-rich habitats, poor fens or bog pools, depressions in rocks, rarely on rocks with trickling water; 0--3440 m; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Nun., Ont., P.E.I., Que.; Alaska, Colo., Conn., Maine, Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., Vt., Va., Wash., Wis.; South America, Eurasia (including Papua New Guinea), s and e Africa, Atlantic Islands, Australia, Pacific Islands (New Zealand), Kerguelen Islands.


A variety of W. fluitans, var. falcata (C. E. O. Jensen) H. A. Crum & L. E. Anderson (Drepanocladus fluitans var. uncatus H. A. Crum, Steere, & L. E. Anderson) has been recognized. However, because no type material seems to be extant, the status of this taxon cannot be evaluated.


2. Warnstorfia pseudostraminea (Müller Hal.) Tuomikoski & T. J. Koponen, Ann. Bot. Fennici 16: 223. 1979


Hypnum pseudostramineum Müller Hal., Bot. Zeit. 13: 501. 1855; Calliergidium pseudostramineum (Müller Hal.) Grout; Calliergidium pseudostramineum var. hoveyi Grout; C. pseudostramineum var. plesistramineum (Renauld) Grout; Drepanocladus pseudostramineus (Müller Hal.) G. Roth


Plants medium-sized, green, yellow-green or brownish, never red; axillary hairs with 1--3-celled distal portion. Stem leaves almost straight or slightly falcate (rarely more strongly falcate), narrowly ovate-triangular or ovate, gradually narrowed to acuminate or often obtuse or blunt point, leaf apex often hooked (incurved over leaf), concave; margins ± entire or finely denticulate; costa ending 65--80% up the leaf; alar cells in usually indistinctly delimited isodiametric or, more rarely, transversely triangular group, supra-alar cells often large and then together with alar cells often forming an oval or rectangular group along proximal leaf margins.


Mineral-poor and acid habitats, apparently favored by disturbance, slightly sloping poor fens, ditches or periodically water-filled depressions; 0--2160 m; Greenland; B.C., Nfld., Ont.; Alaska, Calif., Minn., Wash., Wyo.; Europe.


Warnstorfia pseudostraminea is usually readily recognizable in the field, where it gives an impression of an intermediate between W. fluitans and Straminergon stramineum. It could be confused with W. fluitans or green plants of Sarmentypnum exannulatum and the distinguishing characters of these species are given in their respective discussion. The genus Calliergidium, in which W. pseudostraminea was sometimes placed is discussed under Drepanocladus. Warnstorfia pseudostraminea is widespread in lowlands of northern Europe, and it seems likely that this is the case also in North America.





Ireland, R. R., G. R. Brassard, W. B. Schofield and D. H. Vitt. 1987. Checklist of the mosses of Canada II. Lindbergia 13: 1--62.