BFNA Title: Amblystegiaceae
Author: L. Hedenäs 
Date: February 14, 2008
Edit Level: R2 
Version: 2b

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. Amblystegiaceae G. Roth

 

Lars Hedenäs

 

Plants small, medium-sized, or large; green, yellowish, or brownish. Stem distichously branched, sometimes almost unbranched; cortex of small and incrassate cells; hyalodermis present or not; pseudoparaphyllia mostly foliose, the outer occasionally filamentose; paraphyllia absent or present; rhizoids red-brown, smooth or warty-papillose, slightly or strongly branched; rhizoids or rhizoid initials on stem at or just below leaf insertions or from lower back of costa, occasionally from leaf lamina near leaf apex (Conardia); axillary hairs mostly well developed. Stem leaves straight or falcate (gradually curved) or squarrose, plicate or smooth; costa single and mostly long, or double and usually short; median lamina cells linear or short-linear, rarely rectangular or hexagonal, 1-stratose or sometimes partially 2- or multistratose, smooth or rarely prorate or papillose; alar cells differentiated or not, sometimes inflated. Inner perichaetial leaves straight and erect, lanceolate or ovate or oblong or slightly obovate, plicate or rarely smooth; costa usually well developed, single or double; vaginula with paraphyses. Seta long or rarely short, smooth. Capsule cylindric or short-cylindric, curved and horizontal to straight and erect, stomata long-pored; annulus separating or not; operculum conic or rarely rostrate or short-rostrate. Peristome perfect or specialized; perfect exostomes yellow-brown or brownish, cross-striolate or sometimes reticulate on outer surface below, papillose distally, with dentate or slightly dentate margin and an exostome border ± widened at zone of transition in outer peristomial layer pattern; specialized exostome teeth variously narrow or short, sometimes with outer surface basally papillose; perfect endostomes with high basal membrane, segments long and not or narrow-perforate, cilia nodose or sometimes appendiculate; specialized endostomes with basal membrane ± reduced or sometimes absent, cilia short to absent, segments narrower and sometimes shorter than in perfect endostomes. Calyptra cucullate, smooth.

 

Genera 20--30, species 100--150 (18 genera, XXX species in the flora): temperate to sub-polar regions worldwide, tropical mountains.

 

The Amblystegiaceae as here circumscribed, excluding the Calliergonaceae, include several genera or species groups that may not belong to or are even unlikely to belong to this family in a strict sense. These include Calliergonella, Campylophyllum, Conardia, Donrichardsia, most of Hygrohypnum, Platylomella, Sanionia, and Tomentypnum. At the moment, however, knowledge of the relationships of these taxa is still limited, and they are therefore included with the Amblystegiaceae. The genus Amblystegium is here understood in a wide sense, including Hygroamblystegium, but excluding Serpoleskea (here treated in Platydictya).

 

Members of the Amblystegiaceae are sometimes confused with those of other pleurocarpous families, such as the Brachytheciaceae and Plagiotheciaceae. Most members of the Brachytheciaceae and Plagiotheciaceae differ from those of the Amblystegiaceae in their non-plicate and often recurved rather than plicate and erect inner perichaetial leaves (in species with horizontal capsules). In the Brachytheciaceae horizontal capsules are swollen rather than cylindric, the stomata round-pored rather than long-pored, and the exostome base is mostly red or brown-red rather than yellow-brown. The exostome teeth borders are gradually narrowed upwards rather than suddenly widened where the outside pattern of the teeth changes from cross-striolate to papillose, the endostome segments are widely rather than narrowly perforate, and the spores mature in the winter rather than the summer half of the year in temperate areas. Plagiotheciaceae members have pale whitish yellow exostomes and, in addition, differ from the Amblystegiaceae in several diagnostic gametophyte features, including rhizoid position and ornamentation, and branching mode (see Platydictya treatment). On the other hand, the morphological differences between members of the Amblystegiaceae s. str. and those of other families, such as the Hypnaceae and Thuidiaceae, or the sometimes segregated or recognized Campyliaceae, Cratoneuraceae, Donrichardsiaceae, and Helodiaceae, are more diffuse. Differences between the Amblystegiaceae and the Calliergonaceae are discussed under the latter.

 

SELECTED REFERENCES Hedenäs, L. 2003. Amblystegiaceae (Musci). Flora Neotropica, Monograph 89: 1--107. Hedenäs, L. and A. Vanderpoorten. 2007. The Amblystegiaceae and Calliergonaceae. In: A. E. Newton and R. Tangney, eds. Pleurocarpous Mosses: Systematics and Evolution. The Systematics Association Special Volume Series 71, pp. 163--176. Vanderpoorten, A., B. Goffinet, L. Hedenäs, C. Cox, and A. J. Shaw. 2003. A taxonomic reassessment of the Vittiaceae (Hypnales, Bryopsida): evidence from phylogenetic analyses of combined chloroplast and nuclear sequence data. Plant Syst. Evol. 241: 1--12. Vanderpoorten, A., L. Hedenäs, C. Cox, and A. J. Shaw. 2002. Phylogeny and morphological evolution of the Amblystegiaceae (Bryopsida). Molec. Phylog. Evol. 23: 1--21. Vanderpoorten, A., L. Hedenäs, C. Cox, and A. J. Shaw. 2002. Circumscription, classification, and taxonomy of Amblystegiaceae (Bryopsida) inferred from nuclear and chloroplast DNA sequence data and morphology. Taxon 51: 115--122.

 

1. Leaves with wide 2--5-stratose border or intramarginal band of rectangular or linear cells, sometimes 1-stratose near leaf base and leaf apex.

2. Leaves with 2--4-stratose marginal border; margin denticulate; plants creeping, irregularly to subpinnately branched..................................................................................................... 18. Platylomella, p. xx

2. Leaves with 2--5-stratose intramarginal band; margin dentate; plants dendroid.
........................................................................................................... 17. Limbella, p. xx

1. Leaves without clearly differentiated multistratose border or intramarginal band.

3. Stem with at least a partial hyalodermis.

4. Stem leaves plicate or strongly so; costa single and long............... 12. Sanionia, p. xx

4. Stem leaves smooth; costa single and long, or short and double.

5. Species in or close to running water or lake shores; costa in most leaves either single and long, double or branched and ending in mid-leaf, or short and double; when short and double median leaf lamina cells 27.5--66 \um ............................................................. 3. Hygrohypnum (in part), p. xx

5. Species in various wet and humid habitats; costa short and double; median leaf lamina cells 42--115(--145) \um.............................................................................. 14. Calliergonella, p. xx

3. Stem without hyalodermis.

6. Alar cells of stem leaves not differentiated from other basal cells; costa single.

7. Golden yellow plants with strongly plicate leaves; leaf apex longly acuminate; often with numerous, strongly branched rhizoids from proximal abaxial surface of costa. 13. Tomentypnum, p. xx

7. Green or brownish plants with smooth leaves; rhizoids sparsely branched, never from abaxial surface of costa.
......................................................... 11. Hygroamblystegium (in part), p. xx

6. Alar cells of stem leaves more or less differentiated, small or inflated, sharply or diffusely delimited from surrounding cells; costa single or double.

8. Stem leaves at most 1 mm.

9. Rhizoids or rhizoid initials present on abaxial surface of costa or on lamina near leaf apex; rhizoids warty-papillose and often strongly branched, then forming tomentum. 15. Conardia, p. xx

9. Rhizoids or rhizoid initials only on stem or at abaxial costa insertion, never on leaves; rhizoids smooth or rarely granular-papillose, slightly to strongly branched, rarely forming tomentum.

10. Stem leaves from erect to spreading base recurved or squarrose, at least along some shoot portions; acumen when differentiated distinctly furrowed.

11. Stem leaf costa short and double, often ending in a spine on back of leaf; scattered distal lamina cells usually distally prorate on dorsal side, at least in some branch leaves; seta relatively short, 8--22 mm.

12. Most or many leaves with clearly differentiated acumen; leaf apex acuminate or narrowly so......................................................... 16. Campylophyllum, p. xx

12. Leaf acumen not differentiated; leaf apex acute or blunt.
................................................. 3. Hygrohypnum (in part), p. xx

11. Stem leaf costa long and single, or sometimes shorter and double in some (rarely all) leaves, not ending in a spine on back of leaf; distal lamina cells smooth; seta often long, 12--45 mm.

13. Largest cells in proximal half of alar group in stem leaves 18--25 \um wide; paraphyllia often present, narrow-lanceolate to ovate-lanceolate; autoicous; endostome cilia nodose.
..................................................... 11. Pseudocampylium , p. xx

13. Largest cells in proximal half of alar group in stem leaves 10.5--19(--21) \um wide; paraphyllia absent; dioicous; endostome cilia nodose or partially appendiculate.  6. Campyliadelphus, p. xx

10. Stem leaves variously straight or falcate, but not recurved to squarrose; acumen plane or almost so.

14. Plants submerged in brooks and rivers, sometimes on irrigated rocks; leaves almost orbicular, broadly ovate, or ovate; in the latter case stem leaves either with broadly rounded apex or alar groups well differentiated............................. 3. Hygrohypnum, p. xx

14. Plants terrestrial (sometimes on shores). Leaves varying around ovate; leaf apex acuminate, if blunt with alar cells weakly differentiated from other basal cells.

15. Costa double and short.............................. 4. Platydictya, p. xx

15. Costa single.

16. Capsule straight and erect; operculum short-rostrate; exostome teeth short, papillose throughout; endostome lacking basal membrane and cilia; plants usually growing as epiphytes on trees, sometimes on rotten wood. 5. Anacamptodon, p. xx

16. Capsule curved and horizontal; operculum conic; exostome well developed, teeth cross-striolate basally; endostome with basal membrane, cilia mostly well developed; plants of various habitats................................ 11. Amblystegium, p. xx

8. Stem leaves longer than 1 mm.

17. Stem leaves from erect to spreading base recurved or squarrose, at least along some shoot portions; acumen distinctly furrowed.

18. Stem leaves to 1.7 mm; alar cells slightly inflated, widest alar cells 10.5--17.5(--21) \um wide.................................................................... 6. Campyliadelphus, p. xx

18. Stem leaves at least 1.6 mm; alar cells strongly inflated, widest alar cells 17--31.5 \um wide.

19. Stem leaf costa double and short; alar cells forming an ovate or rectangular group along basal margin of leaf, extending from leaf margin 28--33% of distance to leaf middle at insertion; dioicous.
....................................................................... 7. Campylium
, p. xx

19. Stem leaf costa single and long, or often double and short in at least some leaves; alar cells forming a transverse-triangular group, extending from leaf margin 67--100% of distance to leaf middle at insertion; autoicous......... 9. Drepanocladus (in part), p. xx

17. Stem leaves variously straight or falcate, but not recurved to squarrose; acumen plane or furrowed.

20. Paraphyllia present on stem, occasionally rare and visible only in youngest shoot portion; rhizoids stem-borne, often forming tomentum.

21. Stem leaves plicate; at least some median lamina cells usually prorate or papillose abaxially; paraphyllia linear or lanceolate-linear.
....................................................................... 2. Palustriella, p. xx

21. Stem leaves smooth; median lamina cells smooth; paraphyllia ± lanceolate.

22. Monoicious; alar cells green to brownish-orange, not or slightly inflated; stem leaves lanceolate, entire to finely denticulate throughout. XX. Hygroamblystegium (in part), p. xx

22. Dioicious; alar cells mostly inflated and hyaline; stem leaves triangular, broadened at base, serrate in the proximal 1/3
................................................................ 1. Cratoneuron
, p. xx

20. Paraphyllia absent; rhizoids rarely forming tomentum; when much branched usually inserted on proximal abaxial surface of costa.

23. Stem leaf costa double or forked, short or ending up to mid-leaf or slightly above.

24. Alar cells quadrate to long-rectangular, more or less strongly incrassate, inflated or slightly inflated; alar group indistinctly delimited, large, transverse-triangular; axillary hairs early yellow or brownish.......................... 10. Pseudocalliergon, p. xx

24. Alar cells and alar group different; axillary hairs hyaline when young.      3. Hygrohypnum (in part), p. xx

23. Stem leaf costa single and long.

25. Alar cells of stem leaves distinctly delimited from surrounding cells.

26. Alar cells not or slightly inflated; frequently in streams or on wet rocks.         3. Hygrohypnum (in part), p. xx

26. Alar cells strongly inflatedl; usually in other wet habitats than running water.   9. Drepanocladus (in part), p. xx

25. Alar cells of stem leaves gradually delimited from surrounding cells.

27. Rhizoids or rhizoid initials present abaxially on costa or on lamina near leaf apex; rhizoids warty-papillose and strongly branched, often forming tomentum.        15. Conardia, p. xx

27. Rhizoids or rhizoid initials only on stem or abaxially on costal insertion, never on leaves; rhizoids smooth, slightly to strongly branched, rarely forming tomentum.

28. Alar cells of stem leaves mostly incrassate to strongly so, rarely thin-walled in mature leaves; axillary hairs well developed, abundant, with early yellowish or brownish distal cells.
.............................................. 10. Pseudocalliergon, p. xx

28. Alar cells of stem leaves thin-walled or slightly incrassate in mature leaves; axillary hairs well developed and abundant or small, delicate and sparse, with young distal cells hyaline.

29. Leaf apex rounded or blunt; costa ending 1/2--3/4 way up leaf; plants submerged in brooks and rivers, sometimes on irrigated rocks. 3. Hygrohypnum (in part), p. xx

29. Leaf apex acuminate; if blunt or obtuse then costa ending in or just before apex; plants of various habitats, sometimes submerged.

30. Stem leaf costa ending 60--75% of way up leaf, (45--) 52.5--114 \um wide near base; median lamina cells 42--117 \um. 8. Leptodictyum, p. xx

30. Stem leaf costa ending in distal acumen to percurrent, or ending somewhat farther down in acumen (in latter case, 29.5--58(--77.5) \um wide near base); median lamina cells (9--)13--65(--67) \um.
................... 11. Hygroamblystegium (in part), p. xx