Common and Confusing Bipinnate-Dimidiate Adiantums of Tropical America

4 Pages·1991·2.7 MB·English

by  David B Lellinger

99-102
(1991)
American Fern Journal 81(3):
Common
Bipinnate-Dimidiate
and Confusing
America
Adiantums Tropical
of
David Lellinger
B.
Museum Smithsonian Institution,
Natural History,
Department Botany. National of
of
DC
20560
Washington,
Adiantum with bipinnate fronds
species of
Seven widespread neotropical
much same
the
pinnules look superficially
dimidiate
and nearly oblong,
small,
cajennense
These A.
species,
commonly in herbaria.
misidentified
and
are
and
termmatum,
serrafodentatum
puJveruIentum,
/uliginosum,
fnictuosum,
um
X ana oy
oiien
indument [observed at 50
lamina
indument and abaxial
j
costa
pinna
However,
morphology.
and rhizome
morphology
and pinna
frond
m
phology
with
long-
species
regard
rhizomes. [In this
and the tenacious
excavate press
whereas those
base
the
have that are straight at
rhizomes tend stipes
creeping to
and
so
curve the base,
at
have that
tend stipes
rhizomes to
with short-creeping
made
the
can be in
sometimes
morphology
rhizome
about
an educated guess
rhizome
isence of the itself.)
Adiantum hybrid
Many
species of
of the
Kramer
making
identifications.
in
fficulty
r=^
rSurinam
i^^^jr^jt^^^-^:-^
:;- hJ. onr.a's .
.
m
pinna
hybrids
intermediateness of
Z
Bng'"'^ (P"'^
According Dr.
to
deduced. ">^^^
can be
one parent often
at least
°'
^"*/=
P^"^''"
have passed as v'^'^"*';
many specimens that
the
comm.), of
actual hj''"''^- J*^"^
Adiantum species, are y
forms"
certain
bipinnate of
1^' genus
""elate d
the
simitosituation in
begun a
Moran comm.) has to find
[pers.
Llndsaea
mistaken
evuiv^^ a^x..^ ^-
edaphically ary naoiiais, aavt; .^ m
^^^r^„r»?tioc
communities
may grow genus
and
by non-pteridologists,
each other
for
& Wagner
(Wagner
Adiantum^
SuornTk
species of
these critical
distinguish
wi^r erve to
toltowing y
y
using as
avoided
have it
^^^„^j„,
zome .^ ^ ^^^f^, I
herbarium
from
absence
frequent
because of
keys its
n the
sheets.
Indument the
of
hairs
jointed
simple,
bearing
laminae
mixture
Rhizo
distally.
and hair-like
Droximally
de
crowded.
—
knotted; stipes
ma
u
n T_j..„:„ Vilarkishl at
r,-TrolTr
.,r,
/uliginosum
by veins
subtended
2(4)
VOLUME NUMBER
AMERICAN FERN JOURNAL:
100 81 3 (1991)
when
(commonly brownish young), usually
Indusia blackish maturity
2. at
some them subtended by
of distinctly elongate, (2)3-4(6) veins.
ferminatum
A.
2.
narrow
Abaxial surface of the laminae glabrous or bearing scales, these
1.
sometimes and resembling branched
bearing short teeth or dissected hairs.
more
False indusia per pinnule, usually than times longer
3. 1 linear, 5
than wide, borne along the acroscopic margin of the pinnule but never
extending to the pinnule apex or distal margin. Abaxial surface of the
pinnules bearing a few dissected scales resembling branched hairs.
Rhizomes crowded.
short-creeping, knotted; stipes
pulverulentum
A.
4.
3. False indusia 2-several per pinnule, elongate, mostly less than 4 times
longer than wide, often on the distal margin and/or the pinnule apex,
as well as the acroscopic margin of the pinnule.
4. Pinnules subtending the apical pinnule ca. 1/2 as long as the longest
pinnules indument and
of the pinna; of the rachis costae lax, pale
few wide
(often whitish), linear scales a cells at the base grading to
dissected resembling branched Rhizomes
scales hairs. long-creeping;
cm
1-2
stipes mostly distant; abaxial surface of the pinnules bearing
dissected scales, often glabrescent A. serratodentatum
3.
4. Pinnules subtending the apical pinnule ca. 1/4 as long as the longest
pinnules of the pinna; indument of the rachis and costae firm, tan to
brownish, few wide
linear, subentire to toothed scales a cells at the
base, lacking dissected scales resembling branched
hairs,
5. Scales of the axes at maturity appearing reddish-brown in mass at
low
magnifications, the larger ones decidedly toothed, the
linear,
when
smaller ones, present, nearly entirely dissected into hair-like
cm
processes. Rhizomes long-creeping; stipes 1-2 distant; scales
on
the abaxial surface of the pinnules like those of the axes, the
pinnules 3-6
often glabrescent; false indusia per pinnule.
A. CQJennense
5.
5. Scales of the axes at maturity appearing medium to dark brown in
mass low
at magnifications, linear, scantily decidedly
all to
Rhizomes
toothed.
short-creeping or long-creeping, stipes
cm
approximate up
or
to 1 distant.
6. Scales of the axes and on the abaxial surface of the pinnules
toothed only
linear, near the base; pinnules never the
falcate,
sterile apices always round; indusia 5-10 per
false short,
pinnule, pale Rhizomes somewhat
maturity.
at short-creeping,
knotted, the rhizome decidedly
scales bicolorus, their cells
elongate, the lumina not obvious; approximate.
stipes
A. fnictuosum
6.
6. Scales of the axes and on the abaxial surface of the pinnules
decidedly
linear, toothed, those pinnules reduced
of the often
COMMON AND ADIANTUMS
CONFUSING BIPINNATE-DIMIDIATE
LELLINGER: 101
and resembling branched hairs; pinnules usually falcate, the
apices usually acute, sometimes round; false indusia
sterile
4-7
definitely elongate, per pinnule, blackish at maturity.
Rhizomes long-creeping, not knotted (short-creeping, usually
and
knotted in the Guianas and Brazil rarely elsewhere), the
the
rhizome scales concolorous, their cells relatively short,
cm
up (approximate the
lumina distant in
obvious; stipes to 1
Guianas and A. tetraphyllum
Brazil) 7.
Adiantum ftiliginosum Fee, Gen. 116. 1852.
Fil.
1.
nee
Adiantum hirtum Tijdschr. Natuurl. Gesch. Physiol. 7:428. 1840,
Splitg.
1810, nee Klotzsch, 1844.
Poir.,
named which
Many have been A. terminatum,
species is
collections of this
pinnule shape
frond
because no consistent characters of or
not surprising
and
terminatum.
robust than are those of A.
Amazonian with
Surinam and Brazil,
known
from
and Mickel
by
Proctor
Lesser Antilles (1977),
the
to
Trinidad.
does not include in the flora of
(1985)
it
Meded. Kon. Nederl.
Adiantum terminatum Kunze ex Miq. Versl. Inst.
Inst.
2.
Wetensch. 1842:187. 1843.
nee
nee 1810, Splitg..
Adiantum Linnaea 18:553. 1844, Poir.,
hirtum Klotzsch,
1840.
Amazonian named A. terminatum actually
Most from Brazil is
the material
of
comment under A. /uliginosum.
A. /uliginosum. See the
Venezuela,
known from Guatemala, Nicaragua, Costa Rica,
This species
is
Amazonian
and
Colombia Guyana, Surinam, Brazil.
Bolivia,
to
PL 5:445
Adiantum Humb. & Bonpl. ex Willd. Sp. ed. 4,
serratodentatum
3.
1810.
this
Lam
latifolium
and
serratodentatum
many pinnules like A.
and
pinnules pairs of lateral
A.
more those of
apices like
with acute
pinnules
elongate, oblong or triangular
between the parental species.
indument intermediate
Axis also
latifolium. is
and
Venezuela,
Trinidad,
known from Costa Rica to Bolivia,
This species
is
and Paraguay.
the Guianas southeastern Brazil
to
PL 1753.
Adiantum pulverulentum 2:1096.
Sp.
L.
4.
_
most because of
Among Adiantum, distinct its
this
dimidiate species of is
the
pinnule.
edge the
and always on the acroscopic of
borne per pinnule
linear sori 1
and
apex
pinnule
whose extend the
to
by sori
approached only A. villosum.
It is
more
latifolium
known
from
VOLUME NUMBER
AMERICAN FERN JOURNAL:
102 81
3 (1991)
Adiantum
cajennense Willdenow ex Klotzsch, Linnaea 18:552. 1844,
5.
much
In pinna shape this species very like A. /ructuosum, but can be
is
it
distinguished by long-creeping rhizomes with distant The
stipes. lateral
its
pinnae of this species rarely exceed 15 cm, whereas those of A. /ructuosum and
A. tetraphyJIum commonly The
do. original spelling of the epithet, cajennense,
is correct Latin, and there appears to be no reason to preserve the "corrected"
spelling cayennense,which was adopted by most authors
until recently.
known
This species from Colombia, Ecuador, and eastern Venezuela the
is to
Guianas and and
central northern Brazil.
Adiantum
fructuosum
synonym
of A. tetraphyJIum
The
the kev rhizome
characters.
that of A. tetraphyJIum from the Guianas and Brazil; the pinnae are like the
of A. cajennense in their shape and smaller
size.
known
This species from Cuba, southern Mexico, Guatemala, Costa Rica
is
Peru, Trinidad and Venezuela, and
Brazil.
Adiantum
Humb. &
tetraphyllum Bonpl. Willd
ex.
The
pinnule
sterile apices of this species, at least
ii
fructuosum
pinna The may
the apex. pinnules themselves
/ructuosum
they
are
morphology
with any
other
characters.
known
from
throughout America
tropical
Literature
Cited
Kramer,
The
K. U. 1978. Pteridophytes of Suriname. Natuurwetenschappelijk
Suriname
en de Nederlandse
Antillen. Utrecht. Netherlands.
New
New
York
las. Botanical Garden, York, NY.
Antilles, Vol. Pteridophvta. Arnold Arboretum
2.
MA.
Plain,
Wagner,
W.
and Wagner.
H., Jr. F. S. 1983. Genus communities as a systematic tool in the study
New
World
of Botrychium
(Ophioglossaceae). Taxon 32:51-53.
Announcement
Annual
Review
of Pteridological Research, Vol. 3 compiled by
(for 1989), Cirr
Moran
K. and Robbin
R. Moran,
Missouri
C. Botanical Garden, 72
Louis. pp
St.
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