BFNA Title: Drepanocladus
Author: L. Hedenäs 
Date: February 26, 2008
Edit Level: R
Version: 4

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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AMBLYSTEGIACEAE-- Drepanocladus
 
XX. DREPANOCLADUS (Müller Hal.) G. Roth, Hedwigia 38 (Beibl.): 6. 1899, conserved name * [Greek drepane, sickle, and clados, branch]

Lars Hedenäs

Hypnum subsect. Drepanocladus Müller Hal., Syn. Musc. Frond. 2: 321. 1851; Calliergidium (Renauld) Grout.

 

Plants medium-sized or rather large, green, yellow-green, yellowish or brownish. Stem sparsely and irregularly to more or less pinnately branched ± in one plane, with central strand and without a hyalodermis; paraphyllia absent; rhizoids or rhizoid initials only on stem or at abaxial leaf costa insertion, smooth, slightly or occasionally strongly branched; axillary hairs with 1--3 distal hyaline cells. Stem leaves erect-spreading to spreading, straight or falcate, or from erect, sub-clasping base ± erect to spreading, sometimes squarrose, ovate, rounded-triangular, or cordate, gradually or suddenly narrowed to longly acuminate to obtuse apex, not plicate, concave, above sometimes channeled; marginal lamina cells 1-stratose, margin plane, entire or slightly denticulate; costa double and short or single and long, sometimes excurrent; median lamina cells linear, smooth; differentiated alar cells numerous, distal cells quadrate or shortly rectangular, slightly widened, proximal cells shortly rectangular to shortly linear, inflated and hyaline, widest cells 17--31.5 \um wide, forming a distinct transversely triangular or ± quadrate group, reaching from leaf margin (25--)40--100% of distance to leaf middle at insertion, not decurrent except in D. cardotii. Sexual condition autoicous, synoicous or dioicous. Inner perichaetial leaves gradually or suddenly to narrowed acuminate apex, plicate or slightly so; margin entire or finely denticulate distally; lamina cells smooth. Capsule cylindric, curved and horizontal; peristome perfect; exostome margin entire or slightly dentate above. Spores 11--31.5 \um.

 

Species 10 (7 in the flora): nearly worldwide.

 

Species of the genus Drepanocladus are found in ± mineral- and ± nutrient-rich habitats. They may be relatively large (stem leaves up to 3.6 mm long and 1.5 mm wide), but under relatively dry conditions weak phenotypes occur, the leaves are either erect-spreading to spreading, straight or falcate, with a plane acumen, or from a sub-clasping base ± erect to spreading, sometimes squarrose, with a channeled acumen, and the costa is single and long or double and short. Both the leaf costa and the lamina cells are smooth. The more basal alar cells are inflated (widest cells 17--31.5 /um wide) and do sometimes differ from the distal alar cells, the alar group is transversely triangular or approximately quadrate, and extends from the leaf margin 60--100% of the distance to the costa at the leaf insertion. The outer pseudoparaphyllia are foliose. The seta is tall 17--34 mm, the exostome border is strongly widened where the exostome pattern changes from cross-striolate to papillose, and the endostome cilia are sometimes appendiculate above. Differences between members of Drepanocladus and those of Campylophyllum and Campyliadelphus are discussed under Campyliadelphus, characters separating Drepanocladus from Campylium are mentioned under Campylium, characteristics differentiating Drepanocladus from Sanionia and Drepanocladus are discussed with these genera, and features separating Drepanocladus from Hamatocaulis, Loeskypnum, Scorpidium, or Warnstorfia are pointed out in the notes after the family description. The genus Calliergidium has been distinguished from Drepanocladus bu acute to obtuse leaf apices. However, the type of this genus, C. bakeri (Renauld) Grout, is a synonym of Drepanocladus aduncus, and Calliergidium is thus a synonym of Drepanocladus. This genus is widely distributed in the Holarctic region, in the temperate regions of the southern hemisphere, and in higher mountains in tropical and subtropical areas. Out of the ten species, seven occur in North America.

 

SELECTED REFERENCES Hedenäs, L.1996. On the interdependence of some leaf characters within the Drepanocladus aduncus-polycarpus complex. J. Bryol. 19: 311--324. Hedenäs, L. 1997. A partial generic revision of Campylium (Musci). The Bryologist 100: 65--88.  Hedenäs, L. 1997. Notes on Drepanocladus arcticus (Williams) Hedenäs. J. Bryol. 19: 642--645. Hedenäs, L. 1997. The Drepanocladus s. str. species with excurrent costae (Amblystegiaceae). Nova Hedwigia 64: 535--547. Hedenäs, L. 1998. An overview of the Drepanocladus sendtneri complex. J. Bryol. 20: 83--102. 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. Zarnowiec, J. 2001. A taxonomic monograph of the Drepanocladus aduncus group (Bryopsida: Amblystegiaceae). Bielsko-Biala, Lódz Technical University.

 

Note: In the following key, as well as in the species descriptions, the ratios between the lamina cell and leaf sizes should be based on measurements in 8--10 adjacent stem leaves. The total size ranges should be searched for, and the median values of these should be used for the calculations of the ratios.

 

1. Autoicous (in D. cardotii sexual condition unknown); leaves from ± straight and erect bases usually with leaf acumina ± spreading, or squarrose; leaf acumen furrowed.

 

2. Small species, stem leaves 1--1.4 mm; narrowly decurrent 25--75% of distance to leaf below; very rare species . . .  4.  Drepanocladus cardotii

 

2. Medium-sized to large species, stem leaves normally 1.7--3.6 mm (may be shorter in stunted Arctic plants); not or hardly decurrent.

 

3. Stem leaf insertion shallowly curved to almost straight; leaf base when moist concave, erect to ± spreading, acumen gradually differentiated from basal leaf but frequently more spreading than leaf base, straight or falcate, furrowed; costa double and extending 30--50% way up leaf or single and extending 40--65% way up, leaves 0.6--1(--1.1) mm wide; temperate and Arctic species . . . 2. Drepanocladus polygamus

 

3. Stem leaf insertion usually deeply U-shaped; leaf base when moist concave or strongly concave, erect and sub-clasping, acumen usually sharply differentiated from basal leaf and (erect), patent, spreading or squarrose, furrowed or strongly so; costa double and extending less than 25% way up leaf, or if single extending less than 45% way up; leaves 0.6--1.5 mm wide; Arctic species . . .  3. Drepanocladus arcticus

 

1. Dioicous. Leaves falcate-secund to sometimes entirely ± straight and erect; leaf acumen in straight-leafed plants plane or at most slightly furrowed. 

 

4. Stem leaf costa excurrent or longly so, rarely ending a few cells before leaf apex; one or both leaf margins often partly finely denticulate  . . . 5. Drepanocladus longifolius

 

4. Stem leaf costa ending well before leaf apex; leaf margin entire, or occasionally very finely denticulate. 

 

5. Ratio of median leaf lamina cell length (/um) to leaf length (mm) between 37.6--45.6; stem leaves 1.1--2.1 x 0.5--0.7 mm; alar groups quadrate, shortly transversely rectangular, or shortly transversely triangular, not reaching costa; a rare Arctic species . . . 7. Drepanocladus latinervis

 

5. Ratio of median leaf lamina cell length (/um) to leaf length (mm) between 17.9--36.5 (in D. aduncus very rarely to 38.2); stem leaves 0.9--5.2 x 0.4--1.6 mm; alar groups variously developed; widespread species, sometimes occurring in Arctic areas.

 

6. Alar groups transversely triangular, reaching costa or almost so; stem leaves variously straight or falcate-secund, the latter especially in small plants growing under relatively dry conditions . . . 1. Drepanocladus aduncus

 

6. Alar groups quadrate or shortly transversely triangular, not reaching costa; stem leaves mostly falcate-secund or strongly so, rarely weakly so, the latter especially in submerged plants . . . 6. Drepanocladus sordidus

 

1. Drepanocladus aduncus (Hedwig) Warnstorf, Beih. Bot. Centralbl. 13: 400. 1903

 

Hypnum aduncum Hedwig, Sp. Musc., 295. 1801; Brachythecium edentatum R. S. Williams; Calliergidium bakeri (Renauld) Grout; Drepanocladus aduncus var. kneiffii (Bruch, Schimper & W. T. Gümbel) Mönkemeyer; D. aduncus var. polycarpus (Voit) G. Roth; D. aduncus var. pseudofluitans (Sanio) Głowacki; D. kneiffii (Bruch,Schimper & W. T. Gümbel) Warnstorf; D. simplicissimus Warnstorf; D. stagnatus Żarnowiec

 

Plants slender to robust. Stem pinnately or irregularly pinnately branched. Stem leaves with slightly curved insertion, straight or usually falcate, ovate-lanceolate, ovate, triangular-ovate, rounded-triangular or broadly ovate, gradually narrowed to (obtuse), acute, or shortly to long-acuminate apex, leaves 0.9--5.1 x 0.4--1.6 mm, concave, acumen in straight-leafed plants plane or at most weakly furrowed; margin entire or occasionally very finely denticulate; costa single, ending in mid leaf or above, well before leaf apex; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 17.9--35.5 (very rarely up to 38.2); alar groups transversely triangular, reaching costa or almost so, not or hardly decurrent. Sexual condition dioicous.

 

The species most likely to be confused with Drepanocladus aduncus is D. polygamus, and the differences between these two are discussed with the latter. Drepanocladus aduncus is frequently also confused with Warnstorfia species, but the latter frequently get red colors when growing in exposed habitats whereas D. aduncus never becomes red. In Warnstorfia species the shoots are radially branched (in sparsely branched specimens this may be difficult to see; distichously branched in Drepanocladus), and the margins are mostly distinctly denticulate in at least some parts of the leaves (most distinct just above the alar groups or near the leaf apex or both; entire or almost so in D. aduncus). When several leaves are checked, rhizoid initials are almost invariably found near the apex of at least some leaves of most Warnstorfia species (very rare only in W. trichophylla), whereas leaf-borne initials are never found in Drepanocladus. Finally the very different ontogeny of the alar cells in these two genera is a safe separating character for the very few specimens that are impossible to identify by means of the above characters (see L. Hedenäs 1987).

 

More or less mineral- and nutrient-rich wetlands, such as eutrophic fens, shores, ditches, or occasionally submerged in pools and lakes, sometimes also in swampy forests; low to high elevations; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ariz., Ark., Calif., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Miss., Mo., Mont., N.C., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Oreg., Pa., S.Dak., Utah, Vt., Va., Wash., Wis., W.Va., Wyo.; Mexico; West Indies; Central America; South America: Eurasia: Africa: Australia: Indian Ocean Islands (Kerguelen): Pacific Islands (New Zealand).

 

Because Drepanocladus aduncus is very variable in habit several taxa have been segregated from this species at one time or another. However, the quantitative characters that were employed for separating these taxa are size-dependent, and molecular evidence suggests that the described expressions are environmentally induced. The phenotypes most frequently recognized at the species level were small plants with short leaf cells and weak costae called D. polycarpus, large plants, with long cells and strong costae called D. aquaticus or D. stagnatus, and intermediate plants called D. aduncus. In addition, specimens with acute or sometimes obtuse leaf apices were called D. simplicissimus or Calliergidium bakeri, but specimens of the latter kind have sometimes typical D. aduncus leaves in some parts of the stems, and “D. simplicissimus leaves” in other parts. The studied two isosyntypes of Hypnum kneiffii var. filiforme S. Berggren consist of the species Drepanocladus sordidus, and D. aduncus and Scorpidium cossonii, respectively.

 

2. Drepanocladus polygamus (Bruch, Schimper & W. T. Gümbel) Hedenäs, Bryologist 100: 82. 1997

 

Amblystegium polygamum Bruch, Schimper & W. T. Gümbel, Bryol. Eur. 6: 60, figure 572. 1853 (fasc. 55--56 Mon. 16. figure 10); Campyliadelphus polygamus (Bruch, Schimper & W. T. Gümbel) Kanda; Campylium polygamum (Bruch, Schimper & W. T. Gümbel) C. E. O. Jensen; C. polygamum var. fluitans  Grout; C. polygamum var. minus (Schimper) G. Roth.

 

Plants medium-sized to rather large. Stem irregularly and sparsely to more or less pinnately branched. Stem leaves with slightly curved insertion, erectopatent to spreading, basal leaf portion sometimes slightly more erect than rest of leaf, straight or falcate, ovate, broadly ovate or rounded-triangular, mostly distinctly narrowed at insertion, gradually narrowed to acuminate apex, acumen not or hardly set off from leaf base, leaves (1.3--)1.7--3.5 x 0.6--1(--1.1) mm, concave, acumen furrowed; margin entire or slightly sinuose; costa single or branched and ending in mid leaf to 2/3 way up leaf, or double and ending before mid leaf; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 25.3--33.3; alar groups transversely triangular, reaching from margin 2/3 to entire distance to costa, not or hardly decurrent. Sexual condition autoicous.

 

More or less mineral- and nutrient-rich wetlands, such as eutrophic fens, shores, ditches, or occasionally submerged in pools and lakes, sometimes also in swampy forests; low to high elevations; Greenland, Alta., B.C., N.B., Nfld., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Fla., Idaho, Iowa, Maine, Mass., Mich., Minn., Mo., N.H., N.J., N.Y., Ohio, Wash., Wis., Wyo; West Indies; Central America; South America; Eurasia (including Papua New Guinea); Africa; Australia; Pacific Islands (New Zealand); Antarctica.

 

Some specimens of Drepanocladus polygamus are very similar to D. aduncus. However, D. polygamus is autoicous, whereas D. aduncus is dioicous, and in most cases at least parts of the shoots of D. polygamus are reminiscent of species of Campylium, such as C. stellatum, with the leaves ± spreading and acumen furrowed. In D. aduncus the leaf acumen is more or less flat in straight-leafed specimens, which are the ones likely to be confused with D. polygamus, and the leaves are not spreading in a Campylium-like fashion.

 

The identity of Campylium polygamum var. longinerve (F. Renauld & J. Cardot) A. J. Grout (Hypnum polygamum var. longinerve F. Renauld & J. Cardot) is unclear, because no type material was available for study.

 

3. Drepanocladus arcticus (R. S. Williams) Hedenäs, Bryologist 100: 82. 1997

 

Chrysohypnum arcticum R. S. Williams, Rep. Canad. Arct. Exp. 1913--18, 4(E): 10. fig. 13--18. 1921; Campylium arcticum (R. S. Williams) Brotherus; C. stellatum var. arcticum (R. S. Williams) L. I. Savicz

 

Plants medium-sized to large. Stem irregularly and often sparsely branched. Stem leaves with usually deeply U-shaped insertion, from erect and sub-clasping base with erect, patent or spreading acumen, ovate, broadly ovate or triangular-ovate, only weakly or sometimes not at all narrowed at their insertions, suddenly or gradually narrowed to an acumen that is (1--)1.2--2.3 times as long as basal leaf, apex acuminate, leaves (1--)1.7--3.6 x 0.6--1.5 mm, concave or strongly concave, acumen furrowed or strongly furrowed; margin entire, or near apex sometimes slightly sinuose; costa double and short, very rarely single and then ending well before mid leaf; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 26--30.2; alar groups large, transversely triangular, reaching from margin 2/3 to entire distance to costa, not or hardly decurrent. Sexual condition autoicous.

 

Rarely found very far from the sea in Arctic areas, in association with lagoons, salt water pools, shore meadows, fens, or in association with bird cliffs, in mineral- and more or less nutrient-rich habitats; low elevations; Greenland, N.W.T., Nunavut, Alaska; Eurasia.

 

Drepanocladus arcticus has frequently been confused with D. polygamus and Campylium stellatum, all occurring in Arctic areas. Amblystegium chrysophyllum var. zemliae C. E. O. Jensen (Campylium zemliae (C. E. O. Jensen) C. E. O. Jensen) may be an older name for Drepanocladus arcticus. However, because no type material of this taxon seems to be extant, and the protologue does not allow certain conclusions regarding its identity, this cannot be decided. Two duplicate specimens from C. E. O. Jensen’s herbarium and originally identified as Campylium zemliae (Umanak, July 1834, Vahl), in H and S, respectively, belong to Drepanocladus polygamus.

 

4. Drepanocladus cardotii (Thériot) Hedenäs, Bryologist 100: 82. 1997

 

Hypnum cardotii Thériot, Bot. Gaz. 30: 125, plate 11, fig. 4. 1900; Campylium cardotii (Thériot) Brotherus; C. stellatum subsp. cardotii (Thériot) Grout

 

Plants small. Stems irregularly and in many shoots sparsely branched. Stem leaves with slightly curved insertion, from erectopatent to spreading base falcate or in some shoots subsquarrose, cordate or broadly ovate, suddenly narrowed to an often curved acumen that is 0.6--1.0 times as long as basal leaf, apex acuminate, leaves 1--1.4 x 0.7--0.8 mm, concave, acumen furrowed; margin finely denticulate or sometimes with larger parts entire; costa usually forked shortly above base, occasionally with 3--4 branches, ending well before mid leaf; ratio of median leaf lamina cell length (/um) to leaf length (mm) 23.6 (only one specimen seen); alar groups transversely triangular, reaching from margin 2/3--4/5 of distance to costa, narrowly decurrent 1/4--3/4 of distance to next lower leaf. Sexual condition unknown.

 

Habitat unknown; 2000 m; Mont.

 

Drepanocladus cardotii is recognized by its small size, its Campylium-like appearance, and by the long-decurrent leaves. This species is only known from the type collection, Avalanche Basin in Glacier Park, Montana, and the exact habitat is unknown;

 

5. Drepanocladus longifolius (Mitten) Brotherus ex Paris, Coll., 10. 1909

 

Amblystegium longifolium Mitten, J. Linn. Soc. Bot. 12: 571. 1869; Drepanocladus aduncus var. capillifolius (Warnstorf) Riehmer; D. capillifolius (Warnstorf) Warnstorf; D. crassicostatus  Janssens

 

Plants medium-sized to large. Stems pinnately or more irregularly branched. Stem leaves with slightly curved insertion, erectopatent to patent, falcate or rarely almost straight, ovate to triangular or broadly rounded triangular, gradually narrowed to long-acuminate apex, leaves 1.5--6.4 x 0.5--1.3 mm, concave, acumen in straight-leafed plants ± plane; margin entire or frequently partly finely denticulate; costa single and strong, excurrent or longly so, rarely ending a few cells before leaf apex; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 16.5--23.9(--25.5); alar groups transversely triangular or narrowly so, reaching from margin 2/3--4/5 of distance to costa, not or hardly decurrent. Sexual condition dioicous.

 

More or less mineral- and nutrient-rich habitats, submerged in lakes and pools, ox-bow lakes, water-filled kettle holes, sometimes periodically dry pools, small and usually slowly flowing brooks, sometimes associated with springs, periodically wet depressions in meadows; low to high elevations; Alta., B.C., Man., N.B., N.W.T., Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Mich., Mont., Oreg., S.Dak., Utah, Wash., Wis., Wyo.; South America; Eurasia; Indian Islands (Kerguelen); Australia.

 

Drepanocladus longifolius differs from all other North American Drepanocladus species in its excurrent leaf costa. Because of this trait, it can hardly be confused with any other Drepanocladus s.l. species in North America except Warnstorfia trichophylla. However, the shoots are radially branched, and the shoots and branch apices pencil-like in W. trichophylla, its leaf margins are more strongly denticulate than in D. longifolius, it frequently becomes red when emergent whereas D. longifolius never gets red, and the axillary hairs consist of 2--7 early brown distal cells (but 1--2 hyaline cells in D. longifolius).

 

6. Drepanocladus sordidus (Müller Hal.) Hedenäs in W. R. Buck, Mem. New York Bot. Gard. 82: 217. 1998

 

Hypnum sordidum Müller Hal., Bot. Zeit. 14: 457. 1856; Cratoneuron sordidum (Müller Hal.) Brotherus; Drepanocladus exannulatus var. mexicanus Cardot; Drepanocladus tenuinervis T. J. Koponen

 

Plants medium-sized, sometimes large or small. Stems pinnately or irregularly pinnately branched. Stem leaves with slightly curved insertion, strongly falcate-secund, rarely only weakly so, ovate, broadly ovate or triangular-ovate, gradually narrowed to acuminate apex, leaves 1.4--5.2 x 0.4--1.4 mm, more or less strongly concave; margin entire or partly very weakly, obtusely denticulate; costa single, ending above mid leaf, mostly in acumen but not excurrent; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 23.3--36.5; alar groups small, quadrate or shortly transversely triangular, reaching from leaf margin 2/5-3/5 of distance to costa, not or hardly decurrent. Sexual condition dioicous.

 

Intermediately mineral-rich, meso- to eutrophic habitats, frequently growing submerged in lakes, pools, and ox-bow lakes, but also terrestrial wetland habitats such as fens; low to high elevations; Greenland; Alta., B.C., Nfld., N.W.T., N.S., Nunavut, Ont., Yukon; Alaska, Calif., Ind., Iowa, Mass., Mich., Minn., N.J., N.Y., Nev., Okla., R.I., Wash., Wis.; Mexico; Central America; South America; Eurasia.

 

Drepanocladus sordidus and D. latinervis are recognized by their almost always strongly falcate leaves, their relatively small alar groups, and their relatively strong, but non-excurrent costa. For the differences between the two, see the notes after the latter. Because the species of the Drepanocladus sendtneri (Schimper ex H. Müller) Warnst. and D. aduncus complexes have only recently been understood, the North American distribution of D. sordidus is at present likely to be incompletely known. The Eurasian and African D. sendtneri is a species of strongly calcareous areas, where it usually grows in shallow fens or in periodically wet depressions. It is most safely distinguished from D. sordidus by a different ratio of median leaf lamina cell length (/um) to leaf length (mm), between 17.9-24.4 (between 23.3--36.5 in D. sordidus). Although no examined specimens originally identified as D. sendtneri from North America have turned out to belong to this species, it may still be premature to completely exclude the possibility that this otherwise widespread species occurs also on this continent.

 

7. Drepanocladus latinervis Warnstorf, Beih. Bot. Centralbibl. 13: 416. 1903

 

Plants small. Stems sparsely and irregularly pinnately branched. Stem leaves with slightly curved insertion, falcate-secund, ovate or broadly ovate, gradually narrowed to acuminate apex, leaves 1.1--2.1 x 0.5--0.7 mm, more or less strongly concave; margin entire or very weakly and obtusely denticulate; costa single, ending just below mid leaf to 4/5 way up leaf; ratio of median leaf lamina cell length (/um) to leaf length (mm) between 37.6--45.6; alar groups small, transversely triangular, shortly transversely rectangular, or quadrate, reaching from leaf margin 1/3--2/3 of distance to costa, not or hardly decurrent. Sexual condition dioicous.

 

Apparently growing in calcareous wetlands in the Arctic, but the exact habitat requirements of this species are unclear; Nunavut; Alaska; Arctic Asia.

 

Considering its wide Arctic Asian distribution, Drepanocladus latinervis is most likely more widespread in North America than the two known records indicate. Drepanocladus latinervis is most similar to D. sordidus, which also reaches into Arctic areas where D. latinervis occurs. Both species have relatively small alar groups, and the two can be safely separated only on the basis of the ratio of median leaf lamina cell length (/um) to leaf length (mm), which is much larger in D. latinervis than in any other Drepanocladus species, namely between 37.6--45.6. The few D. latinervis specimens seen, one of which is from North America, are small, with stem leaves 1.1--2.1 x 0.5--0.7 mm, but because D. sordidus is frequently small in Arctic areas, plant size is not sufficient for their separation.

 

OTHER REFERENCES

 

Hedenäs, L. 1987. On the ontogeny of alar cells in Drepanocladus aduncus, D. exannulatus and some other species. J. Bryol. 14: 753--759.