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BFNA Title: Asterella |
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Asterella
- Aytoniaceae XX. ASTERELLA
Palisot de Beauvois, Lam. Dist. Sci. Nat. 3: 257. 1805 · [aster + ‑ella, little star, for shape of female receptacle] Marie L. Hicks Plants in depressed interwoven patches or partial rosettes,
simple or forked; branching primarily dichotomous or with intercalary
branches, arising ventrally by narrow stipes, clavate, cordate or elongate;
apical innovations occasional, forming cordate or elongate segments. Thalli
20‑‑30 ´ 1.5‑‑6 mm, margins plane or ascending, often undulate, not crenulate;
dorsal side green with purplish margins, underside purple; drying plant
margins curling upward and inward exposing the purple underside, appearing as
blackish‑purple tubes; dorsal epidermis not to very slightly areolate, firm,
persistent; cell walls thin to moderately thick‑walled, trigones small or
absent; oil cells scattered; air pores simple, the openings surrounded by 1‑‑3
tiers of 4‑‑8 scarcely differentiated cells; mid‑ventral thallus 8‑‑15 cells
thick, of compact parenchymatous layers forming a broad keel gradually
diminishing in thickness to the margins; dorsal spongy layers 2‑‑4 cells
thick, containing air chambers lacking photosynthetic filaments; oil cells
scattered; rhizoids dense, some smooth, some with internal pegs; ventral
scales purple, in 2 rows, lunate to ovate with scattered oil cells;
appendages hyaline, white or purplish, 1‑‑2(‑‑3) per scale, triangular to
acuminate, not or scarcely constricted at base. Specialized asexual reproduction absent. Sexual
condition monoecious or dioecious; androecia sessile,
often purplish, in dorsal patches of papillae or in discrete thickened pads
surrounded by small subulate scales; the position of androecia in some
monoecious species may vary from posterior to the gynoecial stalks
(paroecious) to apical on dichotomous branches or short intercalary branches
(autoecious) or antheridial papillae occasionally form a mid‑dorsal streak;
gynoecia terminal on thalli; stalks 0.4‑‑5 cm with one rhizoid furrow, with
or without hairlike scales at bases and/or apices; carpocephala bell‑shaped,
domed, ovate or umbonate with air pores on upper surface, developing 1‑‑4
lobes below, each containing one sporophyte surrounded by an exerted, white
to purplish, pleated conical pseudoperianth that splits into 8‑‑16 apically
connate linear segments, becoming free with age in some species. Sporophyte
capsule spherical, irregularly circumscissile; spores areolate, the areolae
bordered by partitions appearing in silhouette as a wing; elaters 120‑‑250 ´
12‑‑15 µm, 1‑‑3 spiral. Species
ca. 80 (8 in the flora): on soil worldwide. 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 paroecious or autoecious . 2. Spores dark brown; southwestern ... 1. Asterella palmeri 2. Spores yellow or pale brown; eastern or boreal. 3. Androecia distinct, paroecious or autoecious;
pseudoperianth segments free at maturity; boreal‑alpine .....2. Asterella gracilis 3. Androecia inconspicuous, of few papillae at base of
gynoecial stalk; pseudoperianths conical, segments not free; east of 100th
meridian .....3. 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;
southwestern. 5. Carpocephala upper surfaces with fingerlike
protruberances; stalks with hairlike scales at bases and apices; Texas
......4. Asterella echinella 5. Carpocephala upper surfaces smooth or with low
tubercules; stalks with hairlike scales at apices, none at bases; west coast
... 5. 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 dioecious;
west coast .. 6. Asterella
californica 6. Carpocephala green or purplish, the lobes directed
downward; stalks with hairlike scales at base; boreal. 7. Spores and elaters purple; stalks with hairlike
scales beneath carpocephala and at base ..7. Asterella lindenbergiana 7. Spores yellow or pale brown; without hairlike scales
beneath carpocephala; conspicuous white scale appendages forming cluster at
apices of thallus branches ... 8. 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 ´
2‑‑4 mm; epidermis smooth, cells mostly 30 x 25 µm, 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 paroecious, occasionally autoecious; 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 µm;
elaters curved, brown, 2‑spiral, 150‑‑180 µm. Capsules
mature Feb.--Apr. Soil banks in rather dry situations; sw Calif.; Mexico
(Baja California Norte). This
species can be 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
gracilis (F. Weber) Underwood, Bot
Gaz. 20: 61. 1895 Marchantia gracilis F. Weber, Hist. Musc. Hep. Prodr. 105. 1815 Plants green with deep purplish undersides and margins;
branching dichotomous, ventral intercalary branches occasional. Thalli 5‑‑15 ´
1‑‑3 mm; epidermis smooth, cells thin‑walled, 25‑‑35 ´
25‑‑28 µm, trigones small or absent, oil cells few, scattered; air pores
surrounded by 2‑‑3 tiers of 6‑‑8 scarcely differentiated cells; ventral
scales purplish with few oil cells; appendages 1‑‑2, lanceolate. Sexual
condition paroecious; androecia
purplish groups of papillae posterior to bases of gynoecial stalks,
occasionally on separate branches, then ovate; gynoecia terminal on
dichotomous branches; stalks 1‑‑3 cm, naked above, bases purplish with
inconspicuous, subulate, deciduous scales; carpocephala hemispheric, 2‑‑3 mm
across, upper surface smooth, becoming low tuberculate on drying, 2‑‑4 lobed
below; pseudoperianths short, directed obliquely downward, the segments
usually 8, free with age. Sporophyte capsules yellowish‑brown;
spores yellow, 60‑‑85 µm; elaters yellowish, 2‑‑3 spiral, 150‑‑200 µm. Capsules
mature Apr.--Aug. Moist soil over rock, usually calcareous in Arctic‑alpine
areas; Greenland, Alta., B.C., N.W.T., Nun. (Baffin Island); Alaska, Ariz.,
Calif., Colo., Mich., Minn., Mont., N.Mex., Utah, Wyo; Europe; Asia. This
plant has been erroneously known in North America as A. Ludwigii (Schwaegrichen)
Underwood and was listed as such in past publications. According to R. Grolle (1975) the type of A. ludwigii is Mannia triandra. 3. Asterella tenella (Linnaeus) Palisot de Beauvois, Lam. Dict. Sci. Nat.
3:257. 1805 Marchantia tenella Linnaeus, Sp. Pl. 1137. 1753 Plants green with purplish undulate margins and purplish
underside; branching dichotomous, rarely with intercalary branches. Thalli 6‑‑15 ´
1.5‑‑3 mm; epidermis smooth, cells 25‑‑40 ´ 20‑‑25 µm, 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 paroecious, 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
µm; elaters yellowish‑brown, 2‑spiral, 150-‑250 µm. Capsules
mature Mar.--June. Soil over rock near streams; low elevations; Ont.; Que.,
Ala., Ark., Conn., D.C., Ga., Ill., Ind., Kans., Ky., La., Maine, Md., Mass.,
Miss., Mo., N.H., N.J., N.C., N.Y., Ohio, Okla., Pa., R.I., S.C., Tenn.,
Tex., Vt., Va., W.Va. This
species is common in e North America extending westward to Kansas; it has not
been found west of the 100th meridian. 4. Asterella
echinella (Gottsche)
Underwood, Bot. Gaz. 20: 62. 1895 Fimbriaria echinella Gottsche, Dansk. Vid. Sellsk. Skrift. V 6: 367 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 ´ 2‑‑3 mm with margins often undulating and ascending; epidermis
smooth, cells 30‑‑50 ´ 30‑‑35 µm 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 autoecious, 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
µm, elaters brown, 1‑‑2 spiral, 140‑‑200 µm. Capsules
mature May. Soil over rocks, often calcareous, near streams; Tex.; Mexico. The
conspicuous finger‑like tubercules on carpocephala distinguish this species
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. 5. Asterella
bolanderi (Austin) Underwood, Bot.
Gaz. 20: 61 1895 Fimbriaria bolanderi Austin, Proc. Acad. Sci. Phila. 21: 230 1869 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 ´ 2‑‑4 mm; epidermis smooth, cells 30‑‑40 ´
20‑‑30 µm, 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 autoecious, 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 µm; elaters yellow to pale brownish, 2(‑‑3)‑spiral, 150‑‑220 µm. Capsules
mature Mar.--May. Soil of shaded banks; Calif., sw Oreg. The
presence of frequent, short, intercalary branches and paucity of dichotomous
branching distinguishes this species 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. 6. Asterella
californica (Underwood)
Underwood, Bot. Gaz, 20: 60 1895 Fimbriaria californica Underwood, Bull. Ill. Lab. Nat. Hist. 2: 41 1884 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 ´
4‑‑10 mm; epidermis faintly areolate, cells 50 ´ 30 µm 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 dioecious; 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 µm;
elaters yellowish, 1‑‑2 spiral, 250‑‑300 µm. Capsules
mature Jan.--May. Soil of shaded banks in rather dry areas; Ariz. (Gila Co.),
Calif., sw Oreg.; Mexico (Baja California Norte). This
is the only dioecious species 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. 7. Asterella
lindenbergiana (Corda) Lindberg, Musc. Scand. 1. 1879 Fimbriaria lindenbergiana A. Corda in
C. Nees von Esenbeck, Naturg. 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 ´
4‑‑6 mm; epidermis faintly areolate, cells 30 ´ 25 µm 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 paroecious or autoecious, 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 µm; elaters purple, 2‑spiral, 100‑‑150 µm. Capsules
mature July--Aug. Damp, mossy soil, frequently calcareous, arctic‑alpine;
Alta., B.C.; Alaska, Colo., Mont., Oreg., Utah, Wash., Wyo.; Mexico; South
America (Colombia); Europe. The
purple spores and elaters of this species are distinctive and when fruiting
it can be readily separated from other species in the flora on that basis. 8. Asterella
saccata (Wahlenberg) A. Evans,
Contr. U.S. Nat Herb. 20: 276 1920 Marchantia saccata Wahlenberg,
Ges. Nat. Freund. Berlin Mag. 5: 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 ´
2‑‑3 mm; epidermis smooth, cells 20 ´ 30 µm 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 paroecious, occasionally
autoecious; 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 µm; elaters
yellowish, 1‑‑3 spiral, 150‑‑200 µm. Capsules
mature May. Soil in rock crevices, usually calcareous in arctic‑alpine areas;
Greenland; Alta.; Alaska, Minn., Mont., Wash.; Europe; Asia. The
white scale appendages exposed at thalli apices and along upturned margins
are distinctive. 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 also lacks a pseudoperianth and has brown, not
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. Chicago. 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. |
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