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BFNA Title: Aytoniaceae Date: March 18,
2023 |
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8. AYTONIACEAE Cavers Alan
T. Whittemore Thalli
5--60(--90) x 1.5--17 mm, branching dichotomous, often also terminal- or
lateral-ventral; thallus upper surface plane or channel Genera 5, species ca. 115 (5
genera and 20 species in the flora): worldwide, except Antarctica. Members of Aytoniaceae
are common on banks and around rock outcrops, especially in the southwestern
United States, where they survive because of their tolerance of seasonal dessication. Aytoniaceae are unique in Marchantiales in having the air chambers subdivided by secondary walls, through the formation of secondary schizogenous divisions between the developing primary chambers (C. R. Barnes and W. J. G. Land 1907; Evans 1918). If these secondary walls reach the epidermis, then the upper surface will have more areoles than air pores; but, if they only reach the epidermis for some of their length, these areoles will be incomplete and confluent but still visible. If the secondary walls stop completely short of the epidermis, there will be one areole per pore as in other Marchantiales. Two of our species, Asterella palmeri and Plagiochila rupestris, lack these secondary subdivisions entirely. The generic classification of this family requires critical revision. The traditional genus Asterella is heterogeneous and clearly unnatural. The exserted, longitudinally slit pseudoperianth has been considered a synapomorphy for the genus, but molecular data (D. G. Long et al. 2000; D. B. Schill et al. 2010; E. A. Borovichev et al. 2015) indicate that it is ancestral in the family and has been independently lost in several clades. More study is required, but results to date suggest that Asterella californica and A. palmeri may not belong in Asterella. SELECTED REFERENCES. Barnes, C. R. and W. J. G. Land. 1907. Bryological
Papers. I. The Origin of Air Chambers. Bot. Gaz. 44: 197--213. Evans,
A. M. 1923. Rebouliaceae. North American Flora Ser.
I, 14: 39--56. Long, D. G., M. Möller, and J. Preston. 2000. Relationships of Asterella (Aytoniaceae,
Marchantiopsida) inferred from chloroplast DNA
sequences. Bryologist 103: 625--644. 1. Carpocephalum dorsal on thallus; disk small, involucres spreading horizontally. Secondary walls of air chambers, if present, reaching epidermis, connected by perforations, thus secondary areoles complete and closed. Appendages of ventral scales subulate to circular. 5. Plagiochasma 1.
Carpocephalum terminal on thallus (sometimes
appearing lateral); disk moderate to large, involucres descending. Secondary walls
of air chambers various. Appendages of ventral scales subulate to lanceolate. 2.
Sporophyte surrounded by a prominent, longitudinally cleft pseudoperianth
that is strongly exserted from the involucre. 3. Pseudoperianth segments linear or narrowly lanceolate, adjacent segments ± equal in width; segments separated by linear slits that are narrower than adjacent segments, slits all ending ± equidistant from pseudoperianth apex and segments remaining attached apically (tardily separating in A. tenella); segment margins narrowly but strongly revolute when dry, flattening and closing gaps between segments when hydrated; pseudoperianth apex rounded or weakly beaked. 1. Asterella, p. xx 3. Pseudoperianth segments linear or lanceolate from broadly triangular bases, separated by gaps that are irregular in width, but most of the gaps on any one pseudoperianth are wider than the adjacent segments, some gaps extending to apex and others ending well below apex of pseudoperianth, segment apices separating at maturity; segment margins plane or only weakly revolute when dry, gaps between segments not closing when hydrated, apex strongly beaked. 2. Mannia, p. xx 2.
Pseudoperianth absent. 3. Disk of carpocephalum discoid, projecting beyond involucres; ventral scales usually disrupted, often rudimentary. 3. Cryptomitrium, p. xx 3.
Disk of carpocephalum hemispherical, involucres
projecting beyond disk; ventral scales well developed and intact. 4. Involucres bilabiate; operculum disintegrating. 4. Reboulia, p. xx 4. Involucres not bilabiate; operculum falling intact. 2. Mannia, p. xx 1. ASTERELLA P. Beauv., Dict. Sci. Nat. 3: 257. 1805 * [Diminutive of Greek aster, star, alluding to the shape of the carpocephala] Marie L. Hicks Thallus firm [delicate]; epidermis sometimes with scattered cells each containing a large oil-body; radial walls of cells surrounding pore thin or thick; secondary walls of air chambers not or incompletely reaching epidermis (absent in A. palmeri). Ventral scales well formed, appendage well defined, narrowly ovate to subulate. Antheridia dorsal on thallus, grouped in a well to poorly differentiated receptacle. Carpocephalum terminal (sometimes appearing dorsal in the angles of dichotomies through early formation of innovations beneath them); stalk with a single rhizoid furrow; disk hemispherical or conical involucres bowl-shaped or bilabiate, descending, projecting beyond edge of disk; pseudoperianth present, strongly exserted, linear or narrowly lanceolate segments, adjacent segments ± equal in width, segments separated by linear slits that are narrower than adjacent segments, slits all ending ±equidistant from pseudoperianth apex and segments remaining attached apically (tardily separating in A. tenella), segment margins narrowly but strongly revolute when dry, flattening and closing gaps between segments when hydrated, apex rounded or weakly beaked. Capsule wholly included within pseudoperianth; operculum falling whole or in fragments. Spores yellow, yellow-brown or dark purple, with ridges that anastomose irregularly or form a reticulum. Species ca 80 (7 species in the
flora): on soil worldwide, except Antarctica. SELECTED REFERENCES Evans, A. M. 1920. The North
American Species of Asterella. Contrib. U.S. Nat. Herbarium. 20(8):
247--312. Schuster, R.M. 1992. The Hepaticae and Anthocerotae of North
America. Vol. 6. Chicago. 1. Gynoecial stalks naked, without hairlike
scales at bases or apices; plants paroicous or autoicous . 2. Spores dark brown ... 1. Asterella palmeri 2. Spores yellow or pale brown; eastern 2. Asterella tenella 1. Gynoecial stalks with hairlike
scales at bases or apices (or both). 4. Thallus branches primarily lateral intercalary;
androecia on short stipitate branches, occasionally on main thallus. 5. Carpocephala upper
surfaces with fingerlike protruberances; stalks
with hairlike scales at bases and apices; Texas ......3. Asterella echinella 5. Carpocephala upper
surfaces smooth or with low tubercules; stalks with
hairlike scales at apices, none at bases; west
coast ... 4. Asterella bolanderi 4. Thallus branches primarily dichotomous; androecia on
main thalli or its dichotomous branches. 6. Carpocephala pale green
with spreading lobes and long pale hairlike scales
beneath, base of stalk naked; plants dioicous .. 5. Asterella californica 6. Carpocephala green or
purplish, the lobes directed downward; stalks with hairlike
scales at base. 7. Spores and elaters purple; stalks with hairlike scales beneath carpocephala
and at base ..6. Asterella lindenbergiana 7. Spores yellow or pale brown; without hairlike scales beneath carpocephala;
conspicuous white scale appendages forming cluster at apices of thallus
branches ... 7. Asterella saccata 1. Asterella palmeri
(Austin) Underwood, Bot. Gaz. 20: 63. 1895 Fimbriaria palmeri Austin, Bull. Torrey Bot. Cl.
6: 47. 1875 Plants green with
purplish undulate margins and deep purple ventral side; branching dichotomous
or thalli simple; intercalary lateral branches rare. Thalli 5--10 x 2--4 mm; epidermis
smooth, cells mostly 30 x 25 \um, thin‑walled, with very small trigones, oil
cells absent; air pores surrounded by 1--2 tiers of 5--6 cells with slightly
thickened radial walls; ventral scales imbricate, deep purple with scattered
oil cells; appendages 1--2, purplish or hyaline, subulate to acuminate, often
with few small marginal teeth, extending slightly beyond thallus margins at
apices. Sexual
condition paroicous, occasionally
autoicous; androecia small dorsal group of papillae at posterior base of gynoecial stalks or occasionally forming mid‑dorsal
streaks of papillae; gynoecia terminal on principal thalli; stalks naked,
without hairlike scales at bases or apices, 1--2
cm, purplish; carpocephala high‑domed to ovoid or
conical, about 4 mm high, 2.5 mm wide, with 3--4 lobes directed downward; pseudoperianths white, conelike,
cleft 1/3--1/2 the length into 8--10 or more segments with attached apices.
Sporophyte capsules dark brown;
spores dark brown, 60--80 \um; elaters curved, brown, 2‑spiral, 150--180 \um.
Soil banks in rather dry situations; low to moderate
elevations; sw Calif.; Mexico (Baja California
Norte). Asterella palmeri is recognized when fruiting by the dark brown spores.
Other species have yellow or purple spores except A. echinella, which has pale brown
spores and is unlikely to be confused with A. palmeri because of the strongly
tuberculate carpocephala of the former. 2. Asterella tenella
(Linnaeus) Palisot de Beauvois, Dict. Sci. Nat. 3:258. 1805 Marchantia tenella Linnaeus, Sp. Pl. 2: 1137.
1753 Plants green with
purplish undulate margins and purplish underside; branching dichotomous,
rarely with intercalary branches. Thalli
6--15 x 1.5--3 mm; epidermis smooth, cells 25--40 x 20--25 \um, walls not to
slightly thickened, trigones absent or small; oil cells few, scattered; air
pores surrounded by 1--3 tiers of 4--6 scarcely differentiated cells; ventral
scales purple with few scattered oil cells; appendages 1--2, white,
lanceolate. Sexual
condition paroicous, androecia of
inconspicuous papillae at posterior base of gynoecial
stalk; gynoecia in apical notch of main thalli; stalks naked, often purplish,
1--3 cm, without hairlike scales at bases or
apices; carpocephala bell shaped, smooth, 3--4 mm
across, lobes 3--4, short, directed downward; pseudoperianths
white or purplish, conical, of 8--12 segments, connate at their apices,
occasionally free with age. Sporophyte
capsules pale yellowish brown; spores yellow, 85--100 \um; elaters yellowish‑brown,
2‑spiral, 150--250 \um. Soil over rock near streams; low to moderate
elevations; Ont.; Que., Ala., Ark., Conn., D.C., Ga., Ill., Ind., Kans., Ky.,
La., Maine, Md., Mass., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa.,
R.I., S.C., Tenn., Tex., Vt., Va., W.Va. Asterilla tenella is common in
e North America extending westward to Kansas. 3. Asterella echinella (Gottsche) Underwood, Bot. Gaz. 20(2): 62. 1895 Fimbriaria echinella Gottsche,
Mexik. Leverm., 271. 1863 Plants green above
with deep purple pigmentation along margins and below; branching intercalary
from a simple or dichotomous main thallus; lateral‑ventral branches frequent,
arising by narrow stalks, the distal portions often obcordate; apical
innovations also occur. Thalli 10--30 x 2--3 mm with margins often undulating and
ascending; epidermis smooth, cells 30--50 x 30--35 \um with slightly
thickened walls, without distinct trigones; air pores surrounded by 1--2
tiers of 6--8 cells; ventral scales deep purple with scattered oil cells;
appendages 1--2, white or purplish tinged, subulate to acuminate, 3--4 cells
wide, slightly narrowed at base. Sexual condition autoicous, male branches short, obcordate, sometimes
innovating apically; androecia terminal, deep purple, oblong, ovate or
subcordate, thickened, the margins with small subulate scales; gynoecia on
principal branches or short innovative branches; stalks 0.5--1.5 cm, reddish
tinged with hairlike scales at apices and sparse
scales at bases; carpocephala domed, 2--3 mm wide
with conspicuous finger‑like tubercules on upper
surfaces, 1--3 lobed below; pseudoperianths white
to slightly purple, of 8--10 segments, connate at apices. Sporophyte capsules brownish; spores
yellowish to pale brown, 60--100 \um, elaters brown, 1--2-spiral, 140--200
\um. Soil over rocks, often calcareous, near streams; Tex.;
Mexico. The conspicuous finger‑like tubercules
on carpocephala distinguish Asterella echinella from others in the flora. Asterella echinella
was listed by W. S. Sullivant (1856) and L. M. Underwood (1884) as A. elegans,
a plant of Mexico. Subsequently R. Stotler and B.
Crandall-Stotler (1977) listed it as A. elegans subsp. echinella (Gottsche)
Del Rosario in error. Thus far, A.
elegans has not been
found north of Mexico. 4. Asterella bolanderi
(Austin) Underwood, Bot. Gaz. 20: 61 1895 Fimbriaria bolanderi Austin, Proc. Acad. Nat. Sci.
Philadelphia 21: 230 1869 (1870) Plants green
above, deep purple below and along margins, which are undulate and slightly
ascending; branching by numerous short intercalary lateral branches that
arise beneath main thallus; dichotomous branches
few. Thalli 10--30 x 2--4 mm;
epidermis smooth, cells 30--40 x 20--30 \um, the walls slightly thickened,
trigones small or lacking, oil cells few, scattered; air pores scarcely
elevated, with 2--3 tiers of 7--8 cells around the opening; ventral scales
deep purplish‑red with scattered oil cells; appendages 1--2 purplish or
hyaline, lanceolate to acuminate. Sexual condition
autoicous, sex organs on short latero‑ventral
intercalary branches; androecia on very short clavate branches, the androecia
ovate, without surrounding scales; gynoecia on short, obcordate branches,
stalks reddish, 1--3 cm with sparse hair‑like scales at apices, few or none
at bases; carpocephala high domed and bell‑shaped,
2.4--4 mm across, usually 4‑lobed, the lobes directed obliquely downward; pseudoperianths white or reddish tinged, 10--12 cleft,
the segments connate at apices. Sporophyte
capsules yellowish brown; spores yellow to pale brown, 65--100 \um; elaters
yellow to pale brownish, 2(--3)‑spiral, 150--220
\um. Soil of shaded banks; low to moderate elevations;
Calif., sw Oreg. The presence of frequent, short, intercalary branches
and paucity of dichotomous branching distinguishes Asterella bolandera from others of the genus in
the flora. The principal thalli often curl when dry, exposing the dark purple
underside. Asterella bolanderi
subsp. acrogyna
R. M. Schuster, named from a single Texas collection (R. M. Schuster 1985),
was a specimen of Reboulia,
later treated (R. M. Schuster 1992) as Reboulia hemisphaerica subsp.
acrogyna
(R. M. Schuster) R. M. Schuster. 5. Asterella californica (Hampe ex Austin)
Underwood, Bot. Gaz, 20(2): 60 1895 Fimbriaria californica Hampe ex Austin, Hepat.
Bor.-Amer. Exsicc., 135. 1873 Plants pale green to
green dorsally with purple ascending margins and dark purple undersides,
edges tending to curl upward exposing the dark underside when dry; branching
dichotomous, seldom with intercalary branches. Thalli 10--25 x 4--10 mm; epidermis faintly areolate, cells 50 x
30 \um with thin walls, trigones small or lacking, oil cells few, scattered;
air pores surrounded by 2--3 tiers of 6--7 cells with slightly thickened
radial walls; ventral scales purplish with few oil cells; appendages 1--3,
hyaline, triangular‑acuminate. Sexual condition
dioicous; separate male plants often intermingled with female plants;
androecia dorsal, forming thick, distinct ovate or elongate patches,
sometimes with subulate scales around the margins; gynoecia terminal on
thalli, stalks slightly purplish, 1--3 cm with pale, long, fine, hairlike scales at apices, none at bases; carpocephala pale green, 4--5 mm across, hemispheric,
becoming umbonate with age, distinctly lobed with
3--4(--5) lobes directed horizontally outward; pseudoperianths
conical, white with 12 or more segments, connate at apices. Sporophyte capsules yellowish; spores
yellow, 100--120 \um; elaters yellowish, 1--2 spiral, 250--300 \um. Soil of shaded banks in rather dry areas; low to
moderate elevations; Ariz. (Gila Co.), Calif., sw
Oreg.; Mexico (Baja California Norte). Asterella californica is the only dioicous species of the genus in the
flora. The female receptacles are large for the size of the plant and the pseudoperianths are directed
outward horizontally rather than downward. The pale color of the carpocephala is in sharp contrast with the inrolled thalli covering the green upper surface exposing
the dark purple underside. 6. Asterella lindenbergiana
(Corda ex Nees) Lindberg
ex Arnell, Lebermoosstud. Nördl.
Norwegen, 2. 1892 Fimbriaria lindenbergiana Corda ex Nees, Naturgesch. Eur. Leberm. 4: 283.
1838 Plants green, often pigmented with reddish‑purple blotches above,
purplish‑red along the undulate, ascending margins and below; branching
dichotomous, ventral intercalary branches infrequent. Thalli 10--30 x 4--6 mm; epidermis faintly areolate, cells 30 x
25 \um with thin walls and no trigones, oil cells few, scattered; air pores
surrounded by 3--4 tiers of 6--8 scarcely differentiated cells; ventral
scales large, purple with scattered oil cells; appendages 1--2, white,
lanceolate to acuminate. Sexual condition
paroicous or autoicous, androecia posterior to gynoecial
stalks or on separate branches, ovate, with variable number of papillae, or
forming dorsal streaks of papillae; gynoecia terminal on main thalli; stalks
purplish, 1.5--2.5 cm with hairlike scales at bases
and apices; carpocephala 3--4 mm across, conical
with low tubercules above and 3--4 short lobes
directed downward; pseudoperianths pleated, often
purplish, of 12 or more segments with connate apices. Sporophyte capsules purple; spores
deep purple, 80--100 \um; elaters purple, 2‑spiral, 100--150 \um. Damp, mossy soil, frequently calcareous, arctic‑alpine;
moderate to high elevations; Alta., B.C.; Alaska, Colo., Mont., Oreg., Utah,
Wash., Wyo.; Mexico; South America (Colombia); Europe. The purple spores and elaters of Asterella lindenbergiana are distinctive and
when fruiting it is readily separated from other
species in the flora on that basis. 7. Asterella saccata (Wahlenberg) A. Evans, Contr. U.S. Nat Herb. 20(8): 276.
1920 Marchantia saccata Wahlenberg,
Mag. Neuesten Entdeck. Gesammten Naturk. Ges. Naturf. Freunde Berlin 5(3): 296 1811 Plants green above,
purplish along margins and underneath, the thalli curl upward around apical
margins exposing white scale appendages, forming a conspicuous apical tuft;
branching dichotomous, ventral intercalary branches infrequent. Thalli 5--10 x 2--3
mm; epidermis smooth, cells 20 x 30 \um with slightly thickened walls and
small trigones; air pores indistinct, surrounded by 1--3 tiers of 5--7
scarcely differentiated cells, oil cells few, scattered; ventral scales deep
purple, long tapered, with scattered oil cells; appendages 1--2, white, long
tapered lanceolate to acuminate, as long or longer than scales, curling up
around the anterior thalli margins, forming conspicuous white clusters at
apices. Sexual
condition paroicous, occasionally
autoicous; androecia form ill‑defined dorsal streaks of papillae at posterior
bases of gynoecial stalks or on nearby branches;
gynoecia terminal on main thalli, stalks 1--2 cm, purplish with cluster of
white hairlike scales at bases and none at apices; carpocephala 2--3 mm across, ovate, at least 1-‑1/2 times
taller than wide with 3--4 lobes directed downward; pseudoperianths
conical, of 6--8 white segments, connate at apices. Sporophyte capsules yellowish; spores
yellow to pale brown, 80--90 \um; elaters yellowish, 1--3-spiral, 150--200
\um. Soil in rock crevices, usually calcareous in arctic‑alpine
areas; low to high elevations; Greenland; Alta.; Alaska, Minn., Mont., Wash.;
Europe; Asia. The white scale appendages exposed at thalli apices and
along upturned margins distinguish Asterlla saccata. These scale clusters have caused confusion with Mannia fragans,
which has a similar apical cluster. Unconfirmed reports from areas south of
this species' range may represent M.
fragans, which, however, lacks a
pseudoperianth and has brown, never yellow spores. OTHER REFERENCES Grolle, R. 1975. Miscellanea hepaticologica
(141-‑150) J. Bryol. 8: 483--492. Schuster, R. M. 1985. Some new taxa of Hepaticae.
Phytologia 57: 410. Schuster, R. M. 1992. The Hepaticae and Anthocerotae of
North America. Volume 6. Chicago: Field Museum. Stotler, R. and B. Crandall‑Stotler. 1977. A checklist of the
liverworts and hornworts of North America. Bryologist 80: 405--428. Sullivant, W. S. 1856. The Musci and Hepaticae of the
United States east of the Mississippi River. In: A. Gray, Gray's Manual of
Botany Ed. 2, pp. 607--737, pls 1--8. Underwood, L. M. 1884. Descriptive Catalogue of the
North American Hepaticae, North of Mexico. Bull. Illinois State Lab. Nat.
Hist. 2: 1-‑133. 2. MANNIA Opiz, Naturalientausch 12: 646. 1829, conserved name * [For Wenzeslaus Blasius Mann, 1799--1839, Bohemian lichenologist] Thallus firm; epidermis sometimes with scattered cells each containing a large oil-body; radial walls of cells surrounding pore thin or thick; secondary walls of air chambers not reaching epidermis. Ventral scales well formed, appendage ovate to narrowly lanceolate or linear. Antheridia dorsal or terminal on thallus, grouped in a well to poorly differentiated receptacle or scattered over thallus. Carpocephalum terminal; stalk with a single rhizoid furrow; disk hemispherical involucres bowl-shaped, descending, projecting beyond edge of disk; pseudoperianth present or absent, if present strongly exserted, cleft into segments that are linear or lanceolate from broadly triangular bases, separated by gaps that are irregular in width, but most of the gaps on any one pseudoperianth are wider than the adjacent segments, some gaps extending to apex and others ending well below apex of pseudoperianth, segment apices separating at maturity, segment margins plane or only weakly revolute when dry, gaps between segments not closing when hydrated, apex strongly beaked. Capsule wholly included within involucre (within pseudoperianth if present); operculum falling intact. Spores yellow-brown or dark purple, with ridges anastomosing irregularly or forming a reticulum. Species ca. 15 (5 species in the
flora): North America, Mexico, South America, Europe, Asia, Africa. R. M. Schuster (1992) has described a new species, Mannia paradoxa R. M. Schuster, based on a single specimen from New Mexico. This specimen could not be located for additional study, it is very immature and it is unclear what genus it belongs to, so it is not possible to evaluate the taxon at this time. SELECTED REFERENCE. Schill, D. B. 2006. Taxonomy and phylogeny of the liverwort genus Mannia (Aytoniaceae, Marchantiales). Ph.D. dissertation, The University of Edinburgh, Royal Botanic Garden Edinburgh. 1. Branching primarily lateral-ventral, carpocephala on short ventral branches; antheridia scattered on dorsal surface of unmodified thallus-branches; spores dark purple. 1. Mannia californica 1.
Branching primarily dichotomous, carpocephala
terminal on main thallus; antheridia grouped in sessile receptacles,
antheridial receptacles terminal on thalli or anterior to carpocephala;
spores yellow or light brown. 2. Appendages of ventral scales hyaline, projecting conspicuously beyond apices of fertile female thalli. 2. Mannia fragrans 2.
Appendages of ventral scales purplish, never reaching thallus margin. 3. Capsule surrounded by a longitudinally cleft pseudoperianth; paroicous, antheridia clustered at base of carpocephalum stalk. 3. Mannia gracilis 3.
Pseudoperianth absent; autoicous, antheridia in well-defined terminal
receptacles. 4. Epidermis usually rupturing over air chambers, at least on older thallus segments; stalk of carpocephalum naked. 6. Mannia triandra 4.
Epidermis persistent; stalk of carpocephalum with
dense clusters of linear or lanceolate scales at apex and base. 5. Small hyaline oil-cells present in ventral scales; spores 40--57 \um. 5. Mannia sibirica 5. Ventral scales without differentiated cells; spores (65--)70--84 \um. 4. Mannia pilosa 1. Mannia californica (Gottsche ex Underwood) L.C. Wheeler, Bryologist 37: 88. 1935 (1935) Grimaldia californica Gottsche ex Underwood, Bot., Gaz. 13: 114. 1888 Thalli 6--20 x 1.5--3 mm, strongly incurved when dry, ventral branching frequent, upper surface green or blotched with brown or purple, underside blackish purple; epidermis persistent. Ventral scales opaque, blackish purple, sometimes projecting beyond thallus margins, with scattered hyaline oil-cells; appendages 1(--2) per scale, purple, narrowly lanceolate-acuminate and 0.5--0.8 mm long, at least on female apices (usually ovate to broadly lanceolate and 0.2--0.35 x 0.1--0.2 on sterile thallus segments). Sexual condition autoicous or dioicous. Antheridia scattered on dorsal surface of unmodified thallus-branches. Carpocephala on short or somewhat elongate lateral-ventral branches, stalk naked or with a few small scales at base, disk narrowly hemispherical, almost smooth, involucres strongly descending, pseudoperianth none. Spores dark purple, 55--75 \um. Exposed summer-dry soil, often
around rocks, in areas that dry early in the season; 0--1300 m; B.C.; Ala.,
Ariz., Ark., Calif., Nev., N.C., Tenn., Texas, Utah; Mexico (Nuevo Leon, San
Luis Potosi); Europe; Asia; Africa. 2. Mannia fragrans (Balbis) Frye & L. Clark, Univ. Wash. Publ. Biol. 6: 62. 1937 Marchantia fragrans Balbis, Mém. Acad. Sci. Turin, Sci. Phys. 7(10: 76. 1804 Thalli 5--17 x 1--2.4 mm, strongly incurved when dry, ventral branching uncommon, upper surface green or blotched with brown or purple, underside blackish purple; epidermis persistent (rarely rupturing on old, senescent thallus segments). Ventral scales opaque, blackish purple, or margins often hyaline, projecting conspicuously beyond apices of female thalli, with scattered hyaline oil-cells; appendages 1--2 per scale, hyaline, narrowly lanceolate and 0.5--1.5 x 0.2--0.5 on female apices (linear and 0.4--0.7 x 0.1--0.2 mm away from sexual apices). Autoicous or dioicous. Antheridia in poorly set off raised receptacles ca 1 mm across terminating thallus-branches. Carpocephala on elongate thalli, stalk with dense clusters of linear or lanceolate scales at apex, disk flattened-hemispherical, warty, ca 1 mm across, involucres obliquely spreading, pseudoperianth none. Spores yellow or light brown, 60--70 \um. Dry soil among rocks in open
places; 0--3400 m; Greenland; Alta., Man., N.B., Ont., Que.; Alaska, Ala.,
Ariz., Ark., Calif., Colo., Conn., Ga., Ill., Iowa, Kans., Mass., Minn., Mo.,
Nebr., Nev., N.J., N.Mex., N.Y., N.C., Okla., Pa., R.I., Tenn., Tex., Utah,
Vt., W.V., Wis., Wyo.; Eurasia. 3.
Mannia gracilis
(F. Weber) D. B. Schill & D. G. Long,
Bryologist 113: 173. 2010 Marchantia gracilis F. Weber, Hist. Musc. Hepat. Prodr. (Weber), 105. 1815; Asterella gracilis (F. Weber) Underwood Thalli 5--12 x 1.5--3 mm, moderately or strongly incurved when dry, ventral branching rare, upper surface green or ± purplish, plane, underside ± purple, often blackish; epidermis persistent. Ventral scales ± purple, reaching about to thallus margin, with scattered hyaline oil-cells; appendages 1(--2) per scale, ± purple, broadly lanceolate or narrowly elliptical, 0.35--0.5 x 0.1--0.2 mm. Sexual condition paroicous. Antheridia in clusters immediately anterior to carpocephalum. Carpocephala on elongate thalli, stalk naked, disk flattened-hemispherical or low-conic, smooth, involucres obliquely spreading, pseudoperianth present. Spores yellow or brownish, 50--65 \um. Damp soil or rock, often in steep
or boggy areas; 0--3500 m; Greenland; Alta., B.C., Nunavut, Ont.; Calif.,
Colo., Mich., Minn., Mont., Ore., Utah, Wash., Wyo.; Europe, Asia. Until recently, Mannia gracilis was placed in Asterella because it has an exserted, cleft pseudoperianth. The pseudoperianth in Aytoniaceae is hygroscopic, and in our species of Asterella, it controls the release of the spores. When hydrated, the segments of the Asterella pseudoperianth flatten and adjacent segments meet, so the spores are completely enclosed. In dry conditions, the edges of the pseudoperianth segments inroll, allowing the spores to escape between them. In contrast, the pseudoperianth of Mannia gracilis is poorly developed, it does not close when hydrated, and it appears to exert little or no control over spore dispersal. The lack of a functional pseudoperianth supports the molecular data of D. B. Schill et al. (2010), indicating that the correct placement of this species is in Mannia. The name Asterella ludwigii (Schwägrichen) Underwood ex Frye & L. Clark has been incorrectly applied to this species in the past. 4. Mannia pilosa (Hornemann) Frye & L. Clark, Univer. Wash. Publ. Biol. 6: 64. 1937 Marchantia pilosa Hornemann, Fl. Dan. 8(24): 7, pl. 1426. 1810 Thalli 4--20 x 2--4 mm, loosely inrolled when dry, ventral branching rare, upper surface green or blotched with brown or purple, underside reddish purple; epidermis persistent. Ventral scales purplish red, never reaching thallus margin, without hyaline oil-cells; appendages 1 per scale, purplish red, narrowly lanceolate, 0.1--0.5 x 0.04--0.2 mm. Sexual condition autoicous. Antheridia in well-defined terminal receptacles at apex of a short branch. Carpocephala on elongate thalli, stalk with dense clusters of linear or lanceolate scales at apex and base, disk depressed-hemispherical, wrinkled (dry), involucres descending, pseudoperianth none. Spores yellow or light brown, (65--)70--84 \um. Damp earth among rocks; 0--2300 m;
Greenland; B.C., N.W.T., Nunavut, Que.; Alaska, Iowa, Minn., Vt., Wis.;
Eurasia. Mannia pilosa and M. sibirica are difficult to distinguish, and the two most recent revisions of the group, R. M. Schuster (1992) and D. B. Schill (2006), give somewhat different treatments of the species. According to Schill, androecial receptacles of M. pilosa are always on short lateral-ventral branches and those of M. sibirica always terminate elongate thallus segments, but Schuster allows variation in this character. Thorough restudy of the problem would be helpful, but both species are rare in North America, and few fully reproductive specimens are available. 5. Mannia sibirica (Müller Frib.) Frye & L. Clark, Univ. Wash. Publ. Biol. 6: 66. 1937 Grimaldia pilosa var. sibirica Müller Frib., Lebermoose 1(5): 265. 1907 Thalli 7--11 x 1--2 mm, plane or inrolled when dry, ventral branching occasional, upper surface green or blotched with brown or purple, underside reddish purple; epidermis persistent (rarely rupturing on old, senescent thallus segments). Ventral scales opaque, dark reddish purple, or margins often hyaline, never reaching thallus margin, with scattered hyaline oil-cells; appendages 1 per scale, hyaline or purplish, narrowly lanceolate, 0.25--0.35 mm. Sexual condition autoicous. Antheridia in well-defined terminal receptacles ca 1 mm across. Carpocephala on elongate thalli, stalk with dense clusters of linear or lanceolate scales at apex and base, disk depressed-hemispherical, wrinkled (dry), involucres descending, pseudoperianth none. Spores yellow or light brown, 40--57 \um. Wet soil over rock, ledges and
cliffs; 200--500 m; Greenland; B.C.; Alaska, Idaho, Iowa, Mich., Minn., Vt.;
Europe, Asia. 6. Mannia triandra (Scopoli) Grolle, J. Bryol. 8: 487. 1975 Marchantia triandra Scopoli, Fl. Carniol. (ed. 2) 2: 354, pl. 63 [lower]. 1772; Mannia rupestris (Nees) Frye & L. Clark Thalli 5--15 x 1.5--3 mm, plane or wings loosely incurved when dry, ventral branching rare, upper surface green, older tissue becoming light brown, margins and underside greenish brown or purple; epidermis usually rupturing over air chambers, at least on older thallus segments. Ventral scales hyaline or purple, never reaching thallus margin, with scattered hyaline oil-cells; appendages 1 per scale, concolorous with scale, narrowly lanceolate or linear, to 0.2(--0.4) mm. Sexual condition autoicous. Antheridia in well-defined terminal receptacles ca 0.5 mm across. Carpocephala on elongate thalli, stalk naked, disk depressed-hemispherical, wrinkled (dry), involucres descending, pseudoperianth none. Spores yellow, 55--65 \um. Stony soil, often on limestone
cliffs, ledges and streambanks; 0--400 m; Ont., Que., Yukon; Ark., Conn.,
Ill., Ind., Iowa, Mich., Minn., Mo., N.Y., N.C., Ohio, Pa., Tenn., Vt.;
Europe, Asia. 3. CRYPTOMITRIUM Austin ex Underwood, Bull. Illinois State Lab. Nat. Hist. 2(1): 36. 1884 * [Greek cryptos, hidden, and mitra, miter, alluding to involucres hidden below broad disk of carpocephalum] Thallus thin and delicate; epidermal cells without oil-bodies; radial walls of cells surrounding pore thin; secondary walls of air chambers reaching epidermis. Ventral scales ± disrupted and rudimentary, appendage rarely well developed, lanceolate-filiform. Antheridia dorsal on thallus, merely clustered. Carpocephalum terminal; stalk with a single rhizoid furrow; disk discoid involucres strongly bilabiate, descending, not projecting beyond edge of disk; pseudoperianth absent. Capsule wholly included within involucre; operculum falling intact. Spores dark brown, with ridges anastomosing to form an irregular reticulum. Species 3 (1 species in the flora):North America, Central America, South America, Asia, s
Africa. All species of Cryptomitrium grow in deeply shaded habitats that remain wet through the rainy season, then desiccate completely during a long dry season. 1. Cryptomitrium tenerum (Hooker in Kunth) Austin ex Underwood, Bull. Illinois State Lab. Nat. Hist. 2: 36. 1884 Marchantia tenera Hooker in Kunth, Syn. Plant. 1: 45. 1822 Thallus pale green dorsally, pale green or purple ventrally, 0--2 x dichotomous, 6--15 x 3--7 mm, ca 0.4 mm thick, remaining flat when dry (rarely wings becoming infolded near apex); epidermal cells thin-walled, pore surrounded by 7--8 rows of 2 cells which are often poorly differentiated. Ventral scales hyaline or purple, ± reduced, often becoming disrupted into a row of vestiges, sometimes reduced to a row of slime-papillae with 1--2 cells at the base of each; appendage rarely well-developed, lanceolate-filiform. Sexual condition paroicous or autoicous. Antheridia in a usually strongly elongate median group, anterior to carpocephalum (or rarely on an adjacent branch); stalk of carpocephalum naked, fleshy, disk thick-discoid (often flattened-pyramidal when immature), 2--4 mm across, smooth or somewhat warty, its margins membranous or inflated; involucres 3--5, inserted on underside of disk. Spores 40--60 \um. Deeply shaded banks and recesses
beneath roots and stones, along intermittent streams and deep in canyons
where moist all winter but dry in summer; 0--600(--1100) m; Calif.; Mexico;
Central America; South America. Reports from Washington (L. Clark
and T. C. Frye 1928) are based on misidentified
specimens. 4. REBOULIA Raddi, Opusc. Sci. 2: 357. 1818, conserved name * (For Eugene de Reboul, 1781--1851, Florentine botanist) Marie L. Hicks Thallus firm; epidermal cells without oil-bodies; radial walls of cells surrounding pore thick; secondary walls of air chambers extending completely to epidermis. Ventral scales well formed, appendage lance-acuminate or subulate. Antheridia dorsal on thallus, grouped in a well-differentiated receptacle. Carpocephalum terminal (growth often resumed by an apical-ventral innovation); stalk with a single rhizoid furrow; disk hemispherical involucres bilabiate, descending, projecting beyond edge of disk; pseudoperianth absent. Capsule wholly included within involucre; operculum breaking apart and falling in fragments. Spores yellow, with ridges anastomosing to form a regular reticulum. Species 4 (1 species in the
flora): North and South America; Eurasia; Africa; Atlantic Islands. Although Reboulia
has long been regarded as a monotypic genus, M.-C. Boisselier-Dubay et al. (1998) provide evidence that
there are actually four species, only one of which is found
in North America. SELECTED REFERENCES Evans, A.
M. 1923. Rebouliaceae. In C. C. Haynes, M. A. Howe
and A. W. Evans. 1923. Sphaerocarpaceae--Marchantiales, Sphaerocarpaceae,
Riellaceae, Ricciaceae, Corsiniaceae, Targioniaceae, Sauteriaceae, Rebouliaceae, Marchantiaceae. North American Flora Ser. I, Vol. 14(1).
New York Botanical Garden, New York. Frye, T. C. and L. Clark. 1937.
Hepaticae of North America. University of Washington Publ. in Biology,
University of Washington, Seattle. Schuster, R. M. 1992. The Hepaticae and Anthocerotae
of North America. Vol. 6. Field Museum of Natural History, Chicago. 1.
Reboulia
hemisphaerica (Linnaeus) Raddi, Opusc. Sci. 2(6): 357.
1818 Marchantia hemisphaerica Linnaeus, Sp. Pl. 2: 1138. 1753; Reboulia hemispherica subsp. acrogyna (R.M. Schuster) R.M. Schuster; R. hemispherica subsp. dioica R.M. Schuster Thalli 2--4 × 0.5--0.9 cm, elongate, slightly widened
distally; margins somewhat crenulate, undulate; epidermis persistent, smooth;
air pores and areolation indistinct; epidermal cells 45--50 × 30--35 \um with
small bulging trigones; air pores surrounded by 3--5 concentric rings of 6--8
cells each; ventral scales with decolorate margins
and scattered oil cells; appendages 2--3 per scale, linear and hair‑like,
2--3 cells wide, ending in 1--3 single cells. Sexual condition paroicous (rarely polyoicous, but usually with some paroicous thalli in the
mat); androecia reniform to
lunate or reduced and chevron-like, positioned 1--10 mm posterior to the base
of the gynoecial stalk; gynoecium in apical notch,
stalk 1.5--3 cm, purplish; carpocephalum green,
with air pores in the upper portion, 4--5 lobed below, each lobe directed
downward, the slit widening to form a circular opening as the sporophyte
expands. Sporophyte capsule
pale greenish; Spores yellow,
65--80 \um; elaters 250--350 × 10--12 \um, 2--3 spiraled. Soil over
commonly calcareous rock, habitats that are at least periodically moist,
temperate areas; 0--2000 m; Alta., B.C., Man.; Ala.,
Ariz., Ark., Calif., Colo., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Kans.,
Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., Nev., N.H.,
N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex.,
Utah, Vt., Va., Wash., W.Va., Wis.; Mexico; West Indies; South America; Europe;
sw Asia; Africa; Atlantic Islands. Reboulia
hemisphaerica, in its wide distributional
range, exhibits considerable variation. From time to time
these plants have been variously described as autoicous or dioicous as well
as paroicous. The North American populations appear to be rather consistently
paroicous, rarely failing to produce either androecia or gynoecia. When this
failure occurs, some populations may appear to be autoicous or dioicous but
paroicous individuals can usually be found within
the mat of plants. Also, in Reboulia collections, the size of androecia decreases with age and,
before elongation of the gynoecial stalk, androecia
are quite turgid and bear marginal scales. As the gynoecial
stalk elongates and sporophytes mature, the androecia shrink and marginal
scales often fall away. The varieties and subspecies
recognized by R. M. Schuster (1992) do not seem to reflect meaningful
groupings. 5. PLAGIOCHASMA Lehmann & Lindenberg in Lehmann, Nov. Strip. Pug. 4: 13. 1832, name conserved * [Greek plagia, obliquely, and chasma, gaping, alluding to horizontally spreading involucres] Marie L. Hicks Thallus firm; epidermal cells without oil-bodies; radial walls of cells surrounding pore thin or thick; secondary walls of air chambers extending completely to epidermis (absent in P. rupestre). Ventral scales well formed, appendage circular to lance-acuminate or subulate. Antheridia dorsal on thallus, grouped in a well differentiated receptacle. Carpocephalum dorsal; stalk without a rhizoid furrow; disk small, plane to convex; involucres strongly bilabiate, almost horizontal, projecting beyond edge of disk; pseudoperianth absent. Capsule wholly included within involucre; operculum breaking apart and falling in fragments. Spores yellow-brown, with ridges usually anastomosing to form a regular or irregular reticulum over the surface. Species 16 (5 in the flora): North
America, Mexico, West Indies, Central America, South America, Europe, Asia,
Africa, Australia, Pacific Islands (New Zealand). Plagiochasma occurs in
warm climates, on soil or rock, often in habitats subject to periodic
drought. Development of pigment, scales, branching, as well as development of
gametangia and spores is somewhat dependent on rainfall. As
a consequence, the extent of gametophytic development and of spore
production varies with local climatic conditions. This may account for some
of the variation that has resulted in misidentifications and more than 50
synonyms for P. rupestre
alone. Plagiochasma is easily separated from other members of Aytoniaceae by the dorsal position of the gynoecial stalk and by the absence of a rhizoid furrow in
that structure. Three of the species are at the northern edge of their more
southerly ranges and have been found only in Texas. SELECTED REFERENCES: Bischler,
H. 1979. Plagiochasma Lehm. & Lindenb. IV. Les
taxa americains. Rev. Bryol. Lichénol. 45:
253--333. Evans, A. M. 1915. The genus
Plagiochasma and its North American species. Bull. Torrey Bot. Club, 42:
259--308. Evans, A. M. 1923. Rebouliaceae. North
American Flora. New York Botanical Garden, New York. Hicks, M. L. and P. G.
Davison. 1989. Some rare, endemic, and disjunct liverworts in North Carolina.
Castanea 54: 255--261. 1. Scale appendages ovate or
ovate-lanceolate to cordate with obtuse, acute or shortly acuminate apices,
distinctly constricted at the base; upper thallus
surface green, smooth or with slightly elevated air pores. 2. Thallus
3--6 mm wide; scale appendages 9--16 cells broad; gynoecial
stalk short, 5 mm or less; carpocephala often
single on thallus or in dorsal linear series; androecia often on short branch
..1. Plagiochasma wrightii 2. Thallus
5--9 mm wide; scale appendages 15--24 cells broad; gynoecial
stalk up to 1.3 cm; carpocephala 1--3 in series on
main thallus or in a pair distally; androecia often at base of terminal
thallus segment .............................. 2. Plagiochasma crenulatum 1. Scale appendages narrow,
subulate to lanceolate, the base not or slightly constricted; upper thallus
surface dull, somewhat glaucous green or blue‑green, smooth. 3. Air pores
surrounded by single circle of 4--6 thin-walled cells; widely distributed ............................. 3. Plagiochasma rupestre 3. Air pores
surrounded by 3--4 tiers of 7--8 cells each with thickened walls; rare, Texas
..............4 4. Plants
bluish green with numerous oil cells visible as white dots; fertile thalli
segmented, of numerous cuneate to cordate segments
................. 4. Plagiochasma
cuneatum 4. 4. Plants
green, oil cells few, inconspicuous; thalli
lingulate with occasional apical or lateral innovations
..................................... 5. Plagiochasma
landii 1. Plagiochasma wrightii Sullivant in A. Gray, Manual (ed. 2), 688. 1856 Plants light green
with narrow purplish, crenulate, undulate margins, simple or dichotomous or
producing apical or ventral adventitious branches which are widest distally. Thalli 10--20 x 3--6
mm; upper surface smooth, epidermal cells 20--24 x 25--30 \um, with thin
walls and distinct trigones; air pores slightly elevated, surrounded by 2--3
concentric rings of 6--8 cells with thickened radial walls; ventral scales
appendages 1--2, ovate‑lanceolate to cordate, 9--16 cells broad, apices
obtuse, acute or shortly acuminate, constricted at the base. Sexual condition paroicous or autoicous with
both gynoecia and androecia on the same thallus in dorsal series or on a
separate branch; androecia
sessile, thick, ovate to reniform or crescentic, purplish, with subulate
marginal scales; gynoecia 1--3 on
main thallus or single on shorter branches; carpocephala
1--3-lobed, stalks 2--5 mm long with linear scales at base and apex. Spores 75--100 \um;
elaters 200--275 x 8--10 \um, 2--3-spiral. Soil over rock, often limestone
near streams; moderate to high elevations; Ariz., Colo., Kansas, N.Mex.,
N.C., Okla., Tex.; Mexico. 2. Plagiochasma crenulatum Gottsche,
Mexik. Leverm., 266. 1863 Plants green with
purple crenulate, undulate margins; branching dichotomous, apical innovations
lacking. Thalli 10--20 x 5--9 mm;
epidermis smooth, cells ca. 25--35 \um with distinct trigones; air pores
slightly elevated, surrounded by 2--3 tiers of 6--8 cells; ventral scale
appendages 1--2, ovate to cordate with obtuse to acute apices, large, 15--24
cells broad, constricted at the base. Sexual
condition autoicous, androecia usually on ventral
intercalary branches or at base of thallus segments, thick, reniform,
purplish, surrounded by purplish or hyaline lanceolate scales; gynoecia 1--3 per thallus (or 2 in
tandem); carpocephalum 2--4-lobed, stalks purple,
0.5--1.3 cm long with linear‑lanceolate scales at base and apex. Spores 70--80 \um;
elaters 200--325 x 10--12 \um, 2--3-spiral. Wet habitats on soil or rock;
moderate elevations; Ala. (Bibb Co.), Ariz. (Pima Co.); Mexico. 3. Plagiochasma rupestre (J. R. Forster &
G. Forster) Stephani, Bull. Herb. Boissier 6:783. 1898 Aytonia
rupestris J. R. Forster & G. Forster, Char. Gen. Pl., (ed.
2), 148, pl. 74. . 1776 Plants glaucous to
dull greyish green with purple, plane margins, simple or dichotomous, the
segments lingulate with occasional ventral or apical innovations. Thalli 4--7 x 1--3 cm
mm, upper surface smooth and somewhat waxy; epidermal cells 20--25 x 25--30
\um with thin walls and small trigones; air pores inconspicuous, not
elevated, surrounded by a circle of 4--6 scarcely differentiated cells;
ventral scale appendages 1--2, subulate to lanceolate, 4--10 cells wide,
apices acute, ending in 1--2(3) single cells, not to slightly constricted at
the base. Sexual
condition paroicous or autoicous; androecia in dorsal series (often
with gynoecia) or on a separate branch, purplish, ovate to cordate with a
circlet of purplish subulate marginal scales; gynoecia form a linear series of 1--5 scale encircled depressions
along dorsal midline which may be present year round with gynoecia in varying
stages of development; carpocephala 1--3-lobed;
stalks 2--4 mm long with narrow scales at base and apex. Spores 70--85 \um; elaters 200--280
\um x 10--12 \um, 2--3-spiral. Shaded soil, often in dry
habitats over calcareous rock; moderate to high elevations; Ariz., Colo.,
Kans., N.Mex., Okla., Tex.; Mexico; South America; Europe; Africa; Asia;
Australia, Pacific Islands (New Zealand). 4. Plagiochasma cuneatum A. Evans, Amer. J.
Bot. 19: 627, fig. 1--7. 1932 Plants green to
bluish green with blackish purple margins; internal tissue with numerous oil
cells visible as small white dots; branching occasional, dichotomous or by adventitious
branches; fertile plants articulated, with cuneate or obcordate segments. Thalli 7--10 x 3--4
mm; upper surface smooth, firm with frequent oil cells; epidermal cells thin‑walled
with small trigones; pores slightly elevated, surrounded by 2--3 concentric
rings of 7--8 cells with thickened radial walls; scale appendages 1--2 per
scale, subulate to lanceolate occasionally cordate, 5--10 cells broad in the
middle, acuminate, the apices ending in 3--5 single cells, slightly
contracted at the base. Sexual
condition monoicous, androecia and
gynoecia arising at thallus apex, becoming dorsal, often situated near
articulations between thallus segments; androecia
oval to reniform, purplish; gynoecia
dorsal, carpocephala 2--3-lobed, stalks 3--5 mm
long, purple with white linear acuminate acales at
base and apex. Spores 90--100 \um; elaters 200--300 x 10--12 \um, 2--3-spiral. Damp limestone; known from one
site in Travis County, Texas; also Mexico; Central America (Guatemala); West
Indies (Haiti). 5. Plagiochasma landii A. Evans, Bull. Torrey
Bot. Club 42: 298, fig. 7. 1915 Plants
green with plane or undulate margins and few dichotomous branches; oil
cells few; adventitious branches occasional. Thalli 8--10 x 4--7 mm; upper surface smooth, cells about 38 \um,
pores slightly elevated, surrounded by 2--4 tiers of 5--7 cells with
thickened walls; ventral scale appendages (1--)2--3 per scale, subulate to
acuminate, purple, elongate with occasional teeth, not constricted at the
base. Sexual condition paroicous, androecia posterior to gynoecia on same
thallus, sessile, reniform, thick, purplish with marginal scales; gynoecia
usually one per thallus, carpocephala stalks very
short, about 1 mm, carpocephalum 1--3-lobed. Spores 70--80 \um;
elaters 200--235 x 10--12 \um, 2--3-spiral. Moist limestone; in the flora
area only known from Upper Boot Canyon, Big Bend National Park, Tex.; Mexico. EXCLUDED SPECIES: Plagiochasma
intermedium Lindenberg & Gottche of
Mexico and Central America has been reported from
McDowell County, North Carolina. The North Carolina collection area near
Linville Caverns was recently examined (M. L. Hicks and P. G. Davison 1989)
and the only plants found were those of P.
wrightii; none had the poorly developed elaters
or the distinctive air pores with thickened radial cell walls as described
for P. intermedium. The area of
Linville Caverns, disturbed by many visitors, may have had a small colony of P. intermedium, but it is apparently extirpated. OTHER REFERENCES Bischler-Causse, H., S. R. Gradstein, S. Jovet-Ast,
D. G. Long, and N. Salazar A. 2005. Marchantiidae.
Flora Neotropica 97: 1--262. Boisselier-Dubayle, M.-C., J. Lambourdièr,
and M.-C.Leclerc. 1998. Taxa delimitation in Reboulia
investigated with morphological, cytological, and
isozyme markers. Bryologist 101: 61--69. Borovichev, E. A., V. A. Bakalin, and A. A. Vilnet. 2015. Revision of the Russian Marchantiales.
II. A review of the genus Asterella P. Beauv. (Aytoniaceae,
Hepaticae). Arctoa 24: 294--313. Clark, L. and T.C.
Frye. 1928. The Liverworts of the Northwest. Publications Puget Sound
Biological Station 6: 1--194. Evans, A. W. 1918.
The air chambers of Grimaldia fragrans.
Bull. Torrey Bot. Club 45: 235--251. Hicks, M. L. and
P. G. Davison. 1989. Some rare, endemic, and disjunct liverworts of North
Carolina. Castanea 54: 255--261. Schill, D. B., D. G. Long, and L. L. Forest.
2010. A molecular phylogenetic study of Mannia (Marchantiophyta,
Aytoniaceae) using chloroplast and nuclear markers.
Bryologist 113: 164--179. |
