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BFNA Title: Antheliaceae |
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XX. ANTHELIACEAE Schuster Steven L. Jessup Plants sparsely interwoven in
mats with other species, or forming loose patches, spongy to compact
cushions, mats, dense turfs, or indurate crusts. Branches lateral-terminal, the branch replacing ventral lobe of
lateral leaf, or lateral-intercalary, the branch axillary and subtended by ventral
lobe of lateral leaf; flagelliform shoots from basal innovations frequent, infrequent,
or absent. Leaves alternate,
transversely inserted, dorsal insertion weakly succubous, 2-fid or 4-fid;
margins entire, or apex bearing marginal cellular crenulation; underleaves
similar to leaves, slightly reduced to equivalent. Rhizoids absent or infrequent on emergent shoots, infrequent to
abundant on lower stems, scattered or in sparse to dense patches proximal to
underleaves. Specialized asexual
reproduction absent. Gynoecia terminal
on leading shoots; subtending innovations present or absent. Perianth free at base, not connate
with bracts, barely emergent to long-exserted from sheathing bracts, ovate to
elongate, cylindric or three-sided, plicate; perianth mouth lobed, the lobe
margins crenulate, minutely toothed, or ciliate; perigynium a rudimentary
coelocaule or absent. Genera 3, species 4 (3 genera, 4 species in the
flora): Greenland; Canada; United States; Mexico; Central America; South
America; Europe; Asia; Africa; Atlantic Islands; Australasia; Antarctica. Anthelia, Lophochaete, and Hygrobiella share similarity of lateral and ventral leaves, transverse
leaf insertion, leaves not decurrent, trigones absent, oil bodies obscure, minute,
or absent, and cryophilic autecology. Populations are narrowly restricted to cold,
seasonally frozen, perennially wet, arctic, subarctic, hyperoceanic, and
alpine environments. Anthelia juratzkana
is abundant in tundra late-snow melt patches and occurs globally in high
elevation periglacial environments. Lophochaete
is known from Arctic terrain that remained unglaciated during the Pleistocene.
Hygrobiella and Anthelia julacea inhabit cold
hyperoceanic, arctic-alpine wet environments. Retention of ancestral
morphology (relative to Jungermanniineae), shared autecology, and bradytelic
descent, support the hypothesis that Antheliaceae is an isolated monophyletic
vestige of ancient adaptive radiation into cold wet environments. A close evolutionary descent of Hygrobiella and Anthelia was hypothesized by Karl Müller (1948) who placed Anthelia with Hygrobiella in Hygrobiellaceae K. Müll. (nomen nudum). The monotypic subfamily, Hygrobielloideae Schust.
(Cephaloziaceae), excluded Anthelia,
which was assigned to monogeneric Antheliaceae Schust., and monotypic
suborder Antheliineae Schust. (R. M. Schuster 2000). Antheliaceae Schust. is
the oldest available name to encompass Anthelia
and Hygrobiella. Family
circumscription and monophyly of Antheliaceae is robustly supported by
analyses of DNA sequence data (B. Shaw et al. 2015). Lophochaete had been
subsumed in Pseudolepicoleaceae, a family with predominantly antipodal ranges.
Lophochaete is distinct from Pseudolepicoleaceae
in details of both sporophyte and gametophyte anatomy (R. M. Schuster 2000).
Molecular phylogenetic analysis strongly supports Lophochaete as sister lineage to Anthelia in monophyletic Antheliaceae, rooted within
Jungermanniineae, whereas Pseudolepicoleaceae is distantly rooted in
Lophocoleineae (B. Shaw et al. 2015). Hygrobiella
is the basal lineage in Antheliaceae. Sister lineage to Antheliaceae within
Jungermanniineae is undetermined. 1. Leaves 2-fid, sinus less than 0.5 x leaf
length; lamina cell length often 2.5--4x cell width;
branching primarily lateral-intercalary, the branch axillary, subtended by ventral
lobe of lateral leaf; stems with distinct hyalodermis; antheridium
jacket cells developing in tiers; seta with less than 12 rows of
epidermal cells, cortex cells less than 10; spores 23--30 \um ……………………………………..…….3.
Hygrobiella 1. Leaves 2-fid or 4-fid, sinus greater than 0.5 x leaf length;
lamina cell length seldom greater than 2.5--3.0 x cell width; branching primarily
lateral-terminal, the branch replacing ventral lobe of lateral leaf; stems
without a distinct hyalodermis; antheridium jacket cells not tiered,
developing from irregularly joined cells; seta with greater than 12 rows
epidermal cells, cortex cells greater than 10; spores 12--20 \um. 2. Leaves 2-fid; perianth at maturity exserted from bracts less
than 0.5 x perianth length; seta epidermal cell rows 16–24, seta cortex cells
numerous; crystalline fibrous exudate or waxy pruinose residue copious;
capsule ovoid to subglobose. ……………………………..……………1. Anthelia 2. Leaves 4-fid; perianth at maturity exserted from bracts greater
than 0.5 x perianth length; seta epidermal cell rows 14--16, seta cortex of
10--12 outer and 4 central cells; crystalline fibrous exudate or waxy
pruinose residue absent; capsule oblong to ellipsoidal. ……………………………………………………………………………………2.
Lophochaete SELECTED REFERENCES Damsholt, K. 2013. The Liverworts of Greenland.
Nord. Bryol. Soc. Lund. Müller K.
1948. Der systematische Wert von Sporophytenmerkmalen bei den beblätterten
Lebermoosen. Svensk Botanisk Tidskrift Utgifven af Svenska Botaniska
Foreningen 42: 1--16. Shaw, B., B. Crandall-Stotler,
J. Váňa, R. E. Stotler, M. von Konrat, J. J. Engel, E. C. Davis, D. G. Long,
P. Sova, and A. J. Shaw 2015. Phylogenetic relationships and morphological
evolution in a major clade of leafy liverworts (Phylum Marchantiophyta, Order
Jungermanniales): Suborder Jungermanniineae. Syst. Bot. 40: 27--45. Schuster, R. M. 1963.
Antheliaceae fam. n., p 236 in,
Studies on antipodal Hepaticae I. Annotated keys to the genera of antipodal
Hepaticae with special reference to New Zealand and Tasmania. J. Hattori Bot.
Lab. 26: 185--309. Schuster, R. M.
1974. Family Antheliaceae. In: The Hepaticae and Anthocerotae of North
America East of the Hundredth Meridian, Vol. III. New York, Columbia University Press. Pp.
618--681. Schuster, R. M. 1974.
Subfamily Hygrobielloideae (Cephaloziaceae). In: The Hepaticae and
Anthocerotae of North America East of the Hundredth Meridian, Vol. III. New York, Columbia University Press. Pp.
649. Schuster, R. M. 1988. The
Hepaticae of South Greenland. Beiheft zur Nova Hedwigia 92: 1--225. Schuster, R. M. 2000. Austral Hepaticae
Part I. Beih. Nova Hedwigia 118: 1--524.
Schuster, R. M. and K. Damsholt 1974. The Hepaticae of West Greenland
from ca. 66° to 72°N. Meddelel. om Grønland 199: 1--370. Steere, W. C. and H. Inoue 1978. Hepaticae
of Arctic Alaska. J. Hattori Bot. Lab. 44:
251--345. 1. ANTHELIA (Dumortier emend. Schiffner)
Dumortier, Recueil d’observ. Jungerm.:18. Tourney 1835 Silverwort.
[Greek anthēlia, opposite the sun; alluding to the anthelion, the bright
polar atmospheric apparition shining in dark sky at the anthelic point on the
perihelic arc, in reference to reflected silver shine from dark crusts of Anthelia when viewed at the antisolar
point, relative to observer perspective] Steven L. Jessup Plants miniscule to small; forming
spongy to compact cushions, dense turfs, or indurate crusts; dark grey-blue, gray-green,
dark yellow-brown to velvet black, shining silvery gray from reflective felted
crystalline exudate, shoot apices bearing hoary flakes or glaucous film of exudate
deposit; irregularly and sparingly to densely branched; shoots tristichous, terete, filiform,
julaceous. Stems prostrate,
procumbent, ascending; 0.1--1 mm wide, 0.1--4 cm long; hyalodermis
absent; procumbent shoots developing slight dorsiventral symmetry;
branching primarily lateral-terminal, the branch replacing ventral lobe of
lateral leaf; flagelliform shoots from basal innovations present or absent,
not abundant. Leaves transversely
inserted, appearing weakly succubous; 2-fid, concave, conduplicate, patent to
appressed; distant to imbricate at shoot apices; lateral leaves symmetric to
weakly asymmetric; lobe apices often decolorate, blunt, acute, lanceolate, or
acuminate, 1-seriate apex usually 1--2 cells; leaf sinuses narrow, 0.5--0.8 x
leaf length; lamina cell length seldom greater than 2.5--3.0 x cell width;
leaf base decurrency absent; trigones undeveloped; oil bodies not evident. Rhizoids absent or rare on emergent
shoots, infrequent to abundant on lower stems, frequent in sparse to dense
patches proximal to underleaves on mature stems. Sexual condition dioicous or paroicous. Androecia developed as short terminal spikes on leading shoots,
becoming intercalary, or as short lateral branches proximal to or subtending gynoecia,
infrequently becoming intercalary; bracts, bracteoles, and leaves similar,
variably reduced; bract pairs 3–8, imbricate, saccate base of each bract
enclosing an antheridium; antheridium jacket cells not tiered, developing
from irregularly joined cells. Gynoecia
terminal on leading shoots; subtending innovations present or absent; bracts
and bracteoles resembling leaves, free at base, 3-ranked, enlarged toward
apex, imbricate, appressed. Perianth
barely emergent to exserted from sheathing bracts less than 0.5 x perianth
length, ovate to elongate, trigonous at base, deeply plicate, gradually
contracted to wide mouth; lobes few, free 0.5 x perianth length, lobe margins
crenulate, minutely toothed. Perigynium
a rudimentary coelocaul, immersed in shoot tip at maturity, the stem apex
forming a shoot calyptra bearing undeveloped archegonia. Seta epidermal cell rows 16--24; cortex cells numerous. Capsules ovoid to subglobose; wall
2-stratose; outer cells bearing yellow-brown nodular thickenings on
longitudinal and transverse radial walls, inner cells bearing semiannular thickenings.
Spores 12--20 \um; brown; minutely
textured. Elater width 6--9\um;
spiral bands 1--3; band width 2--5 \um.
Species 2, (2 in the flora): North America, Mesoamerica,
South America, Eurasia, Melanesia, Africa, Atlantic Islands, Pacific Islands
(New Zealand), Antarctica. Anthelia expresses a
continuum of phenotypes in response to light, moisture, temperature, and
substrate environment. Both species
form lax patches, sods, mounds and turfs of elongate stems (2–4 cm) in perennially
wet microhabitats. Anthelia juratzkana
is paroicous and often bears sporophytes, whereas Anthelia julacea is dioicous and sporophytes are often sparse or
absent. The species are sympatric across the known range of Anthelia julacea (R. M. Schuster
1969), but syntopic only in wet circumacidic microhabitat. Vegetative
phenotypes are broadly overlapping, and identity of sterile specimens from
mesic and wet habitats is ambiguous. Differences in spore and elater
morphology are consistent across the continuum of phenotypic variation in
gametophytes, enabling quick diagnosis of specimens bearing mature sporophytes. Exposed shoots of both species produce a
copious exudate of crystalline needles, the smallest crystals less than a
micron wide. The crystals coalesce to form a tangled lattice suspended over
the shoot tips, obscuring the shoots in an opaque, sparkling, reflective,
silver-grey crystalline felt, covering the surface in patches from less than
a cm2 to multiple dm2. Shoot tips are typically
glaucescent or frosted with deposits of the exudate. The crystals dissolve
rapidly in organic solvents, in acetone on a microscope slide rapidly
recrystallizing as solution evaporates. Presence of the silvery felt is
diagnostic for occurrence of Anthelia
in cryptobiotic crusts and mats. SELECTED REFERENCES Schuster, R. M. 1969. Problems of antipodal
distribution in lower land plants. Taxon
18:46--91. Schuster, R. M. and K.
Damsholt. 1974. The Hepaticae of West Greenland. Copenhagen. Schuster, R. M. 1988. The Hepaticae of
South Greenland. Beiheft zur Nova Hedwigia 92: 1--225. Schuster, R. M. 2000. Suborder III.
Anthellineae Schust. Austral Hepaticae Part I. Beih. Nova Hedwigia 118: 169--172.
Schuster, R. M., W. C. Steere and J.
W. Thomson 1959. Anthelia (Hygrobiellaceae), pp 61--62 In: Terrestrial Cryptogams
of Northern Ellesmere Island. Nat. Mus. Canada 164. 1. Plants paroicous;
androecia on short lateral branches proximal to gynoecia; perianth ovate,
emergent from gynoecial bracts at maturity; elaters gradually tapered, tips
blunt, 2(--3) spiral bands, 1.5--2 \um wide, coils tight; spores (15--)16--18(--20)
\um. …………1. Anthelia juratzkana 1. Plants dioicous, patches
intermixed or unisexual; androecia and gynoecia terminal on dominant shoots
of separate plants; perianth elongate, exserted from gynoecial bracts at
maturity; elaters abruptly tapered, tips contorted, 2 spiral bands, 3--5 \um
wide, coils relaxed; spores (11--)12--15(--16) \um. …..2. Anthelia julacea 1. Anthelia
juratzkana (Limpricht) Trevis, Mem. R. Ist. Lomb. Ser. 3, 4: 416. 1877 Jungermannia juratzkana Limpr., in Cohn, Krypt.-Fl. Schlesien 1: 289.
Breslau, 1876 Plants miniscule to small, 1--10(--20)
mm; forming compact cushions, mats and crusts in arctic and alpine habitats. Leaves ovate-oblong to
quadrate-oblong; 0.3--0.5(--0.6) x 0.2--0.3(--0.4) mm; 2-fid 0.5--0.8 x leaf
length; cuticle smooth to sparsely punctate. Leaf cells quadrate to rectangular, medially 15--18(--20) x 18--25(--36)
\um; marginal cells quadrate, reduced. Sexual
condition paroicous. Androecia
on short lateral branches proximal to gynoecia. Gynoecia terminal on dominant shoots. Perianth ovate, emergent from gynoecial bracts at maturity; lobes
long, often free to near perianth base; 1-stratose in proximal half. Elaters gradually tapered, tips
blunt, 2(--3) spiral bands, 1.5--2 \um wide, coils tight. Spores (15--)16--18(--20) \um. Dominant or subdominant in patches adjacent to late
snow melt zones, permafrost barrens, tundra, periglacial terrains,
fellfields, cryoplanation terraces, polar desert deflation pavements, rock
outcrops; sea level to highest ice-free peaks and nunataks, oceanic polar
archipelagos, and insular mountaintop environments globally; over thin mineral
soil, crevices in rock outcrops, co-occurring with diverse cryophilic
cryptogams adjacent to névé and firn; 0--4000 m: Greenland; Alta., B.C.,
Man., N.B., Nfld. and Labrador, N.W.T., Nunavut, Ont., Que., Yukon; Alaska,
Calif., Colo., Idaho, Maine, Mich., Mont., Nev., N.H. Oreg.,Wash., Wyo;
Mexico; South America: Venezuela, Colombia, Ecuador, Bolivia, Argentina,
Tierra del Fuego); Europe; Asia (India, Japan, Korea, Nepal, Russia in Siberia);
Malaysia; Africa (Tanazania); Atlantic Islands (Iceland, Falkland Islands,
South Georgia); Pacific Islands (Aleutian Archipelago, New Zealand, Papua New
Guinea); Antarctica (South Orkney Isl., South Shetland Isl.). Anthelia juratzkana thrives in high
elevation and high latitude late-melting snow-bed communities and is codominant in circumarctic Andreaea blyttii Snow Bed Association.
Abundant midsummer sporulation in the Arctic occurs as bird migrations begin,
increasing likelihood that spores and miniscule stem fragments are dispersed in
the dusted feathers of birds. A silvery felted crystalized exudate frequently
covers the surface of crusts. Aeolian sediments of fine sand and dust infiltrate
the felted exudate. Embedded clasts and weathered residue form a coherent
matrix resistant to wetting, fusing plants with substrate. Shoots are often immersed
in the crust with apices barely emergent. Crusts with shoots deeply immersed
in the pale weathered residue superficially resemble sterile terricolous
crustose lichens. Cryoprotective effects, UV-filtering, anti-wetting effects,
water retention, and shading effects of the felt and residue are relevant to
understanding A. juratzkana
autecology. At the extreme limits of habitable environment in
arid High Arctic barrens where liquid water and light are ephemeral, A. juratzkana forms diminutive cryptobiotic
crusts over thin mineral soils adjacent to patches of névé
on rock outcrops and deflation pavements. Cracks in desiccated crusts form
polygonal segments 2--5 cm2. Wind-blown lichen fragments infiltrate
the cracks and, in favorable microhabitats, regenerate to form a cover of diverse
fruticose lichens. Anthelia crusts
and mats host a complex community of cyanobacteria, algae, protists and
microinvertebrates. 2. Anthelia
julacea (Linnaeus)
Dumortier, Recucil d’observ. Jungerm.: 21 Tournay. 1835. Jungermannia julacea Linnaeus,
Spec. plant. ed 1:1135, 1231. Stockholm 1753; Anthelia julacea var. sphagnicola C. E. O. Jensen; Anthelia julacea var. nana Schiffner Plants small, 10--30(--40) mm long; forming lax cushions, turfs,
procumbent mats and cryptobiotic sods,. Leaves
ovate-oblong; 0.4--0.6(--0.7) x 0.3--0.4(--0.6) mm; 2-fid 0.5--0.8 leaf
length; cuticle smooth to sparsely punctate. Leaf cells quadrate to rectangular, medially (12--)15--20 x 20--30(--36)
\um; marginal cells quadrate, reduced. Sexual
condition dioicous, patches intermixed or unisexual. Androecia terminal on dominant shoots. Gynoecia terminal on dominant shoots. Perianth elongate, exserted from gynoecial bracts at maturity to
0.5 x perianth length; lobes short, not free to near perianth base, 1-stratose
in proximal half. Elaters abruptly
tapered, tips contorted, 2 spiral bands, 3--5 \um wide, coils relaxed. Spores (11--)12--15(--16) \um. Wet circum-acidic microhabitats where buffered
against desiccation, in Arctic and alpine periglacial terrains, fellfields,
cryoplanation terraces, tundra; sphagnum mounds, splash zones, melt-water fed
slopes, creek banks, dripping cliffs; 0--1200 m: Greenland;
B.C., Nfld. and Labrador, N.W.T., Nunavut (Baffin Island), Que., Yukon;
Alaska, Mont., Oreg., Wash.; Europe; Asia (China, India, Japan, Russia in Siberia,
Turkey) Atlantic Islands (Iceland, Faeroe Islands, Jan Mayen). Anthelia julacea occurs in
isolated unisexual patches, contiguous unisexual patches, and sexually
intermixed patches. Sporophytes are frequent in intermixed patches, and rare
in isolated unisexual patches. Sterile plants of Anthelia julacea are practically indistinguishable from syntopic
sterile plants of Anthelia juratzkana. 2. LOPHOCHAETE
R. M. Schuster, J. Hattori Bot. Lab. 23:197, 1961. [Greek lophos,
crest, and khaitē, bristle; alluding
to closely imbricate isophyllous stems bristling with attenuate lobe apices
of 4-fid leaves.] Steven L. Jessup †Wilfred B.
Schofield Plants miniscule to small; prostrate,
procumbent, ascending, suberect to erect; brown to yellow-brown, reflective crystalline
exudate absent; irregularly and sparingly branched; shoots tristichous,
julaceous. Stems 0.5--1 mm wide, 1--8
cm; hyalodermis absent; procumbent shoots developing slight dorsiventral
symmetry; branching primarily lateral-terminal, the branch replacing ventral
lobe of lateral leaf; flagelliform shoots from basal innovations absent. Leaves transversely inserted,
appearing weakly succubous; 4-fid, concave, open, divergent to falcate; distant
to densely imbricate at shoot apices; lateral leaves symmetric to weakly asymmetric;
lobe apices not decolorate, lanceolate, acuminate to attenuate, 1-seriate
apex usually 2--5 cells; leaf sinuses wide, central sinus often greater than 0.8
x leaf length; elongate central lamina cell length seldom greater than 2.5--3
x cell width; leaf base decurrency absent; trigones undeveloped; oil bodies not
evident. Rhizoids absent or rare
on emergent shoots, frequent as sparse patches proximal to underleaves on
mature stems. Sexual condition dioicous
or autoicous. Androecia developed as
short terminal spikes on leading shoots, becoming intercalary, or as lateral
branches proximal to gynoecia, rarely becoming intercalary; bracts,
bracteoles, and leaves similar, variably reduced; bract pairs 3--5, imbricate,
saccate base of each bract enclosing an antheridium; antheridium jacket cells
not tiered, developing from irregularly joined cells. Gynoecia terminal on leading shoots; subtending innovations absent
or subtending only unfertilized gynoecia; bracts and bracteoles resembling
leaves, free at base, 3--ranked, enlarged toward apex, imbricate, appressed. Perianth long-exserted from sheathing
bracts greater than 0.5 x perianth length, elongate, cylindrical at base, deeply
plicate, contracted to narrow mouth, short-stipitate with maturity; lobes several,
free 0.2--0.5(--0.8) x perianth length; lobe margins crenulate to ciliate. Perigynium absent, the stem apex
forming a shoot calyptra bearing undeveloped archegonia. Seta epidermal cell rows 14--16; cortex cells 10--12, enclosing 4
central cells. Capsules oblong,
ellipsoidal. Spore diameter 14--18
\um; yellow-brown; minutely granulate. Elater width 8--10 \um; spiral bands 2; band width 3 \um. Species 1 (sensu
lato): North America, Asia. 1. Lophochaete fryei (H. Persson) R. M.
Schuster, J. Hattori Bot. Lab. 23: 201. 1961 Lepicolea fryei Persson,
Bryologist 49: 47. 1946; Pseudolepicolea
fryei (Persson) Grolle & Ando Plants occurring as isolated
stems interwoven with other cryptogams or forming small loose aggregations
and thin mats. Leaves obdeltoid;
0.5--0.6(--0.9) x 0.5--0.6(--0.9) mm; 4-fid, the central sinus extending to within
(3--)4--7(--10) cells above leaf insertion; cuticle smooth to minutely
granulate. Leaf cells quadrate to
rectangular, medial cells of leaf base 18--22 x 22--30(--35) \um; marginal
cells quadrate, reduced. Perianth 1-stratose
in proximal half. Capsule wall
2-stratose; outer cells bearing yellow-brown nodular thickenings on
longitudinal and transverse radial walls, inner cells bearing semi-annular
and annular thickenings. Wet tundra cryptogam mats; 0--1000 m: Greenland
(Wollaston Foreland); Nunavut (Kugluktuk, Chesterfield Inlet, Axel Heiberg
Island, Baffin Island); Alaska (North Slope, St. Lawrence Is., Kotzebue
Sound, Cape Lisburne, Anaktuvuk Pass); Asia (Russia in Siberia). In the Arctic, Lophochaete fryei is restricted to
tundra that was unglaciated during the Pleistocene. Lophochaete fryei is rarely collected and is documented from only
a few Arctic localities, including Arctic hyperoceanic headlands and islands.
Fertile specimens are rare and variation in gynoecia morphology is known from
a small sample. New localities will likely be discovered on close inspection
of specimens where isolated shoots, obscured among other High Arctic
cryptogams, are sparsely interwoven through Blepharostoma mats. SELECTED REFERENCES Damsholt, K. 2013. Lophochaete (Blepharostomataceae), pp 30--32 in, The Liverworts of Greenland. Nord. Bryol. Soc., Lund. Frye, T. C. and L. Clark 1947. Lepicolea, pp. 948--951 In: Hepaticae
of North America. U. Wash. Pub. Biol. 6(5): 735--1022. Schuster, R. M. 1966. Lophochaete (Blepharostomataceae), pp 726--737 In: The Hepaticae
and Anthocerotae of North America East of the Hundredth Meridian, Vol.
1. New York, Columbia University
Press. Steere, W. C. and H. Inoue.1978.
Hepaticae of Arctic Alaska. J. Hattori Bot. Lab. 44: 251--345. 3.
HYGROBIELLA Spruce, On Cephalozia,
p. 73. 1882 [Greek hygrobe, growing
in wet places, plus Latin emphatic diminutive, -iella, alluding to minute plants of wet habitats] Plants miniscule to small;
ascending, suberect to erect; dark green, olive-green, brown, black;
reflective crystalline exudate absent; irregularly and sparingly branched; shoots tristichous, filiform, terete. Stems 0.25--0.8 mm wide, 0.5--2 cm long; hyalodermis present; procumbent shoots developing slight dorsiventral symmetry; branching primarily lateral-intercalary, the branch
axillary, subtended by postical lobe of lateral leaf; flagelliform shoots proliferating
from basal innovations proximally on mature stems, often abundant. Leaves transversely inserted,
appearing weakly succubous; 2-fid, concave, conduplicate to open, patent to
erect-spreading; distant to loosely imbricate
at shoot apices; lateral leaves symmetric to variably asymmetric; lobe apices
not decolorate, blunt to rounded, 1-seriate apex absent; leaf sinus narrow,
acute, less than 0.5 x leaf length; lamina cell length often 2.5--4 x cell
width; leaf base decurrency absent; trigones undeveloped; oil bodies not
evident, minute, or absent. Rhizoids
red-brown, absent or rare distally, sparse, short and scattered proximally,
more frequent on flagelliform shoots. Sexual
condition dioicous. Androecia
developed as lax terminal spikes on leading shoots, becoming intercalary, or
as short lateral branches; bracts and bracteoles, subequal with leaves,
variably reduced; bract pairs 4--8, loosely imbricate, saccate base of each
bract enclosing an antheridium; antheridium jacket cells developing in tiers. Gynoecia apical on leading shoots
from axils of leaves; subtending innovations from axils of bracts and
bracteoles bearing subapical gynoecia; bracts and bracteoles resembling
leaves, variably enlarged; bracteoles free at base, 3--ranked, enlarged
toward apex, imbricate. Perianth
long-exserted from sheathing bracts greater than 0.5 x perianth length,
elongate, fusiform, cylindrical at base, plicate, trigonous at apex, contracted
to narrow mouth; lobes 3, rounded, free at apex; lobe margins crenulate, denticulate
with elongate cellular projections, Perigynium
absent. Seta epidermal cell rows 8
(10--12); cortex cells 4. Capsules
oblong, ovoid to ellipsoidal. Spore
diameter (20--)23--30\um; red-brown; smooth. Elater width 9--12 \um; spiral bands 1
or 2; band width 3--4 \um. Species 1 (1 species in the flora): North America, Europe, Asia (Japan), Atlantic
Islands. 1. Hygrobiella laxifolia
(Hooker) Spruce, On Cephalozia,
p. 74. 1882 Jungermannia laxifolia Hooker, Brit.
Jung. tab. 59. London. 1813 Plants forming loose cushions,
mats, or short dense turfs. Leaves elliptical
to ovate-lanceolate; 0.2--0.3 (0.6--) x 0.4--0.5(--1) mm; 2-fid, the sinus 0.2--0.5
x leaf length; cuticle smooth. Leaf
cells thin-walled, marginally quadrate to medially long-rectangular; medial
cells of leaf base (14--)17--23 x 35--55(--70) \um. Perianth 2--3-stratose in proximal half. Capsule wall 2-stratose, outer cells bearing coarse nodular
thickenings on transverse and longitudinal radial walls, inner cells bearing
semiannular thickenings. Saxicolous, on wet rocky
substrates and compact gravel, in sheet-flow zones, seeps, and inundated substrates
with cold flowing water, rocky stream banks, dripping ledges, spray zones;
subarctic, boreal, hyperoceanic, subalpine to alpine inland; 0--1800 m: Greenland;
Alta., B.C., Labrador, Nfld., N.S., Que.; Alaska, Calif., Idaho, Mont., Oreg.,
Wash.; Europe; Asia (Japan); Atlantic Islands (Faeroes, Hebrides, Iceland,
Shetland Islands). SELECTED REFERENCES Damsholt, K. 2013. Hygrobiella (Cephaloziaceae subfam. Hygrobielloideae). In: The
Liverworts of Greenland. Nord. Bryol. Soc., Lund. Pp. 409--412. Schuster, R. M. 1974.
Subfamily Hygrobielloideae (Cephaloziaceae). In: The Hepaticae and
Anthocerotae of North America East of the Hundredth Meridian, Vol. III. New York, Columbia University Press. P.
649. |
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