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BFNA Title: Bryaceae, family description |
BRYACEAE SchwägrichenJohn R. Spence Plants acrocarpous, but sporophytes
occasionally appearing lateral due to rapid innovating growth; tiny to
robust, as scattered individuals or forming open to dense turfs or cushions, green,
silver, white, golden or red, plants often more than one color. Stems short to long, 0.1--10 cm,
sometimes julaceous, unbranched to sparsely branching by subfloral
innovations, stolons occasionally present; rhizoids sparse to abundant,
variously colored, smooth to papillose, micronemata and/or macronemata often
present. Leaves imbricate to
variously contorted or twisted when dry, erect to erect-spreading when wet,
broadly lanceolate, ovate, ovate-lanceolate, obovate to spathulate, 0.03--6
cm, base straight or curved at insertion, decurrent or not; margins plane or
revolute, 1- or 2-stratose, rarely multistratose, limbidium present or
absent, apex broadly rounded to acute or acuminate, apiculus sometimes
present, costa percurrent or subpercurrent, or excurrent as a short- to
long-excurrent awn, transverse section with stereid band single, usually well
developed, occasionally greatly reduced, with or without guide cells; adaxial
supracostal cells irregularly to regularly quadrate or short- to
long-rectangular proximally, laminal cells relatively uniform throughout
lamina or obscurely to distinctly heterogenous, proximal cells usually
quadrate, short- or long-rectangular, often distinctly different in shape or
occasionally similar to median and distal, medial cells generally similar to
distal cells, distal cells short to very long, hexagonal to rhomboidal,
sometimes vermicular, 2--10:1, sometimes occurring in rows oblique to the
costa, thin- to thick-walled, walls sometimes pitted, alar cells usually
similar to juxtacostal cells, sometimes differentiated into a small group of
quadrate cells. Specialized asexual
reproduction common, of seven distinct types; spherical to ovoid rhizoidal
tubers, filiform rhizoidal gemmae, axillary filiform gemmae, leaf axil
bulbils, stem tubers, slender leafless terminal shoots, or leaf axil deciduous
brood branchlets. Sexual condition
dioicous or monoicous, sometimes variable within species (polyoicous);
perigonia and perichaetia terminal or lateral, perichaetial leaves the same
size as vegetative leaves or typically larger, sometimes forming a rosette,
inner leaves usually highly differentiated, often narrower with a weaker
costa. Seta usually 1, sometimes
polysetous, variously colored, long, straight, twisted or geniculate. Capsule erect, inclined to nutant,
long-exserted, 1--8 mm, ovate, spherical, cylindrical, or pyriform,
occasionally zygomorphic, hypophysis well-differentiated or not, sometimes
expanded and rugose, exothecial cells near mouth quadrate or
short-rectangular, thick-walled, often reddish, in 1--3 or more rows, medial cells
longer, short- to long-rectangular with straight or sinuose walls; annulus
usually present, revoluble; operculum convex, short to tall-conic, sometimes
rostrate; peristome diplolepidous-alternate, rarely reduced to one layer or
absent, exostome white to pale yellow or tan, sometimes reddish, teeth
triangular to lanceolate, trabeculate, sometimes with small pores along
fissural line, endostome hyaline to pale yellow, separate or sometimes
adherent to exostome, segments narrow to wide, usually broadly perforate,
basal membrane low to high, cilia present, 1--3, usually appendiculate, to
variously reduced in number or length or sometimes absent. Calyptra fugacious, cucullate, small,
smooth. Spores shed singly or as
tetrads, rarely germinating in capsule, 8--60 /um, smooth to papillose, pale
yellow, tan or nearly hyaline, rarely darker. Genera 15,
species ca. 500 (10 genera, 106 species in flora): worldwide. The Bryaceae
is a large family of acrocarpous mosses with a global distribution. Many
species are adapted to disturbed soil and are somewhat weedy. Species exhibit a remarkable array of
specialized asexual structures, perhaps more than in any other bryophyte
family. The genus Bryum in the
broad sense has a reputation for being taxonomically difficult. Part of this is because the genus is highly
polyphyletic, and also because, traditionally, many species have been distinguished
by minor differences in peristome features.
Previous classifications have over-emphasized the peristome, placing
taxa with strikingly different gametophytes in the same genus. The
gametophytes of Bryum vary widely
morphologically, and this has been used as a basis to re-classify the genus
and its relatives (J. R. Spence 2005; J. R. Spence and H. P. Ramsay
2005). Recent genetic
research has radically changed some of our understanding of relationships in
the family. These studies have shown that Pohlia
and related genera, traditionally considered part of the Bryaceae, are more
closely related to members of the Mniaceae. Further, Orthodontium is only distantly related to the Bryaceae, while Leptobryum appears to be closest to
the Meesiaceae (C. J. Cox and T. A. J. Hedderson 2003). Roellia may also be more closely related to the Mniaceae, and for
the flora has been removed to its own family. Within the re-circumscribed
Bryaceae, results based on morphology and genetics do not always agree (N. Pedersen
et al. 2003). Recent attempts to revise generic limits in the family using
DNA evidence have produced large unwieldy clades that defy coherent
morphological description. However, to date most genetics research has
focused on the chloroplast genome, without taking into account the many
critical assumptions underlying the use of DNA sequence data. Recent studies
of portions of the chloroplast genome of land plants have indicated that
lineage sorting, gene transfer, and paralogy may be fairly common, thus potentially
obscuring phylogenetic relationships. Because of these uncertainties, this
treatment is based primarily on the morphology of the gametophyte.
Differences between genetic and morphological approaches are discussed under
each genus. SELECTED REFERENCES:
Andrews, A. L. 1935. Bryaceae. In: Grout, A. J. Moss flora of North America,
Vol. 2. Newfane: Vermont. Cox, C. J.
and T. A. J. Hedderson. 2003. Phylogenetic relationships within the moss
family Bryaceae based on chloroplast DNA evidence. J. Bryol. 25: 31--40. Nyholm, E. 1993. Illustrated flora of Nordic
mosses, Fasc. 3. Copenhagen and Lund: Nordic Bryological Society. Ochi, H. 1980. A revision of the Neotropical
Bryoideae, Part 1. J. Faculty Educ. Tottori Univ., Nat. Sci. 29: 49--154. Ochi, H. 1981. A revision of the Neotropical
Bryoideae, Part 2. J. Faculty Educ. Tottori Univ., Nat. Sci. 30: 21--55. Ochi, H. 1992. A revised infrageneric
classification of the genus Bryum
and related genera (Bryaceae, Musci). Bryobrothera 1: 231--244. Pedersen, N., C. J. Cox and L. Hedenäs. 2003.
Phylogeny of the moss family Bryaceae inferred from chloroplast DNA sequences
and morphology. Syst. Bot. 28: 471--482. Smith, A. J. E. 2004. The moss flora of
Britain and Ireland, Ed. 2, Cambridge. Spence, J. R. 1988. Bryum Hedw. (Bryaceae) in western North America. Bryologist 91:
73--85. Spence, J. R. 2005. New genera
and combinations in Bryaceae (Bryales, Musci) for North America. Phytologia
87: 15--28. Spence, J. R. 2006. New
combinations in the Bryaceae (Bryophyta) for North America. II. Phytologia
89: 110--114. Spence, J. R. and H. P.
Ramsay. 2005. New genera and combinations in the Bryaceae (Bryales, Musci)
for Australia. Phytologia 87: 61--72. Spence,
J. R. and H. P. Ramsay. 2006. Bryaceae. In: Flora of
Australia, Vol. 51, Mosses 1:
274--348. 1. Stems short, mostly less than 10 mm, julaceous; plants green, yellow-green to silver-white; leaves typically less than 1 mm; distal lamina cells long, (2) 3--10:1, proximal cells quadrate to short-rectangular, transition often abrupt; bulbils and rhizoidal tubers sometimes present; dioicous …………………1. Bryum, p. XX 1. Stems short
to long, rarely julaceous (if so then plants reddish); plants green,
yellow-green, red, pink-silver, or rarely hyaline above; leaves (0.5--)1--10 mm;
distal lamina cells short to long, mostly 2--6:1, proximal cells variously
quadrate, short- to long-rectangular, transition abrupt or not; asexual
reproduction of all types present; dioicous or monoicous. 2.
Plants rosulate with obovate to spathulate leaves, margins distally serrate. 3.
Stolons present; leaves large, often greater than 5 mm; costal stereid band reduced;
gemmae lacking ………………9. Rhodobryum, p.
XX 3.
Stolons absent; leaves typically less than 5 mm, if longer then filiform gemmae
present; costal stereid band well developed; rhizoidal tubers and leaf axil
filiform gemmae often present .………… 10. Rosulabryum
(in part), p. XX 2.
Plants comose to gemmiform, bulbiform or evenly foliate, never distinctly
rosulate; leaves ovate, ovate-lanceolate to triangular; margins distally smooth
to serrulate. 4.
Plants typically in dense cushions, golden-silver to pink-silver; leaves with
long, spinose, hyaline awn; distal lamina cells rhomboidal, 3--4:1, proximal
cells quadrate; capsule long-cylindrical, erect; peristome reduced, cilia
absent; epiphytic, corticolous, saxicolous, rarely terricolous ….……5. Leptostomopsis, p. XX 4.
Plants usually not in dense cushions, of various colors; awn present or absent,
rarely hyaline or spinose; distal and proximal lamina cells various; capsule
inclined to nutant, if erect then short ovoid; terricolous or saxicolous,
rarely corticolous. 5.
Plants green, yellow, or red, rarely leaves somewhat hyaline above; laminal
areolation typically heterogenous, distal cells elongate, vermicular, hexagonal,
or rhomboidal, thin- to thick-walled, proximal cells quadrate to regularly short-
to long-rectangular, alar cells not differentiated; capsules terminal;
peristome double; seta rarely somewhat twisted, not geniculate. 6.
Distal lamina cells 3--6:1, longer than the quadrate or short-rectangular
proximal cells; stems gemmiform or elongate and evenly foliate; leaves
imbricate, not contorted or twisted when dry, or if somewhat twisted then
rhizoidal tubers present; limbidium absent or weak, 1-stratose; rhizoidal tubers and leaf axil bulbils often
present. 7.
Plants small, stems mostly less than 1 cm, gemmiform to evenly foliate;
leaves 0.5--2.5 mm; leaf axil bulbils often present, tubers if present on
long rhizioids in substratum or at base of stem, often abundant; capsules
ovate to pyriform, apophysis sometimes inflated and rugose . . . 2. Gemmabryum,
p. XX 7.
Plants medium-sized, stems 1--3 cm, evenly foliate; leaves 1.0--3.5 mm;
tubers if present on micronemata or macronemata on stem, scarce, sometimes
absent; capsules pyriform, neck slender ……….…… …3. Imbribryum, p. XX 6.
Distal lamina cells mostly 2--4:1, the same length or shorter than short- to
long-rectangular proximal; stems comose, to evenly foliate; leaves twisted to
strongly contorted when dry; limbidium usually present, often strong, 1- to 2-stratose;
rhizoidal tubers and leaf axil filiform gemmae, sometimes present, bulbils
absent. 8.
Leaves ovate to obovate, distal margins serrulate to serrate or rarely nearly
smooth, limbidium 1-stratose; rhizoidal tubers usually present, filiform leaf
axil gemmae often present; dioicous …………………………10. Rosulabryum (in part), p. XX 8.
Leaves ovate-lanceolate to ovate; distal leaf margins serrulate to smooth,
limbidium 1- or 2-stratose; rhizoidal tubers absent, leaf axil filiform
gemmae rare; dioicous or monoicous ……………8. Ptychostomum, p. XX 5.
Plants green to silver, pink-silver, pink-green or red-brown; laminal
areolation homogeneous, lax, cells very long, thin walled, 4--8:1, cells near
apex sometimes short or rarely irregularly quadrate, alar cells similar to juxtacostal
cells or sometimes differentiated, in small quadrate groups; capsules
sometimes appearing lateral; peristome double, single or absent; seta often
twisted or geniculate. 9.
Sporophytes appearing lateral; capsules short pyriform to ovate; apophysis
short; peristome of exostome teeth only or absent …….……… 4. Haplodontium, p. XX 9.
Sporophytes terminal; capsules pyriform to distinctly zygomorphic; apophysis
often very long; peristome double. 10.
Capsules zygomorphic; seta often geniculate; spores shed as tetrads; plants
red-brown to silver or silver-pink; rhizoidal tubers absent ………………… 7. Plagiobryum, p. XX 10.
Capsules not zygomorphic; seta straight or somewhat twisted but not
geniculate; spores shed singly; plants green or pink-green, not silvery;
rhizoidal tubers often present. 11.
Rhizoidal tubers small, pyriform, brown, 40--60 /um; lamina cells long and
narrow, less than 15 /um wide,
alar cells quadrate in small group ……………2. Gemmabryum (in part), p. XX 11.
Rhizoidal tubers large, spherical, red, often greater than 200 /um, or
absent; lamina cells long and wide, typically greater than 20 /um wide, alar
cells not quadrate …………… 6. Plagiobryoides,
p. XX |