1990
31
A.H. GENTRY
Herbarium taxonomy versus
Is
there
an
attainable solution?
A.H.
Missouri
Evolution is a
Botanical
complex process
field knowledge.
Gentry
St.
Garden,
Louis,
MI
U. S. A.
63166,
and the species produced by evolutionary processes
are
therefore of necessity not always clear-cut. Problems associated with definition of species boundaries have always plagued taxonomists and, no doubt, always will. However, I would maintain that in most situations there really is a ‘best’ solution to what
kind of taxonomic recognition to accord a specific evolutionary pattern.
The optimum
solution to these kinds of problems depends
in part on taxonomic philos-
ophy. Are species real objective evolutionary entities? (Our job being to find out what
they are.) Or are they essentially artificial constructs whose delimitation more or less
depends on taxonomic convenience and preference? In the latter case, there is no ‘solution’ to the taxonomists’ dilemma. Certainly, many people working in the temperate
Taraxacum
zone, where
rampant autogamy means that
every clonea
of
is
essentially
different microspecies, tend to feel that this is the case. However, many of us working
in the Neotropics feel that species are mostly far better defined and are, for the most
part, quite objective entities. Indeed, as I see it, if species are not in some sense real
units whose nature and limits we are trying to discover via scientific thought processes,
taxonomy would hardly be worth doing, and we should turn our efforts to some other
field of endeavor, say, population genetics, where the scientific method does provide
insight
At least in the
into
subtle characters.
differentiation adapting
two
or a
upland
forest
hard
understand in the herbarium.
If
two
ferent
In
closely
taxon.
These
related
habitats),
then
patterns
species
fulfill
same,
or
even
are
two
greater,
very
different
a
are, for the
taxa
species
of
in
in
a
a
a
to
most
genus
to
part, rather
speciation
field,
roles
is
different sub-
but
(i.e.,
an
extremely
occupy
dif-
of taxonomic recognition.
is looked
at over a
differentiate
different
of
swamp derivative of
clear in the
evolutionary
species
serve
world.
typical pattern
clearly worthy
are
arise when
a
related
usually
differences that
crop up elsewhere in the range of
A
water-dispersal
to
philosophically they
practice, however, problems
The
closely
switch from wind-dispersal
strates,
to
real
Neotropics, distinctions between species
well-defined, although often by
vegetative
the
broader range.
a taxon
evolutionary
locally
context.
may
In other
FLORA
32
in
words,
some
the
places
same
MALESIANA
of
amount
variation may be interpopulational,
BULLETIN
Special
Volume
morphological (and presumably
whereas in others it is
1
genetic)
into distinct
clearly separable
taxonomically circumscribable units.
This kind of
so
would suggest the
tinental
ly
the infamous
pattern,
many taxonomic
headaches,
generality
Neotropics
it is
may
that
morphological differentiation
bility
ling
within
to
trying
within
a
taxa
by
In any event, each
such
work)
in the lowland
into
polymorphic species
in
experience
partitionable
of African
Africa,
the
I
con-
satisfyinglevels of
same
into reasonably
discrete
taxo-
will
an
inordinate
Neotropical patterns,
the
on
than I would be wil-
Bignoniaceae
I have
spent
taxon.
fit the
case
earlier
However,
currently recognize far greater morphological varia-
that different evolutionary processes
day.
be
not to
Neotropical
make the African
to
my
own
for
responsible
solution.
clearly optimum
a
resolve
in my
hand,
tend
to
to
wide-ranging species
most
accept
(contrary
subunits. I
nomically recognizable
have
not
usually possible
discrete entities. On the other
that has been
polymorphic species
but
to no
continents have led
two
certainly have
to
be resolved
of time
amount
avail. It may be
what
to
its
on
see to-
we
own
merits
the taxonomist involved.
Again
in my
-
Madagascar
own
seems
to
and
experience,
follow the
drawing heavily
Neotropical pattern,
on
with
Bignoniaceae
mostly quite
patterns
clear-cut
-
spe-
cies.
What about Malesia? Can useful generalities about the best resolution of
species complexes
ample,
and
the
be arrived at? It
Dipterocarpaceae,
microgeography
who know the
can
rather fine
be worked
Queensland
flora
ecotaxonomically recognizable
recognized
at
a
seems
very
out.
specific
who also worked with
tions for the proper taxonomic
split
them rather
together
many of the
situation,
well that
To
in
some
gathering
through
specific
least in
some
polymorphic
groups
most
Bignoniaceae,
treatment
recent
-
feel that there are
forest,
which
interesting
came
up
of Malesian
ecology
discrete
(and should)
treatment
that Professor
with
two
bignons.
for the Flora
quite
In his
supposed
to
van
be
recent
Steenis,
different soluhe
early work,
Malesiana,
that he had earlier described. Does this reflect
delimitation much harder
ex-
colleagues
generally
can
for
resolution than has been prevalent in
specific
but in his
species
they
where additional collections fill in the
ties and make
change
finely,
at
delimitation correlated with
entities in their rain
far finer level of
-
I also know from discussions with
taxonomy in the Indonesian region. It is
himself,
clear that
an
he
lumps
'African'
gaps between differententi-
define? Or does it merely reflect
a
philosophy?
degree,
a
more
much
there is
a
complete
more
solution
to
this kind of
database, both
intensive field
study.
problem.
It is the obvious
through very many
It is
dramatic what
a
more
one
of
collections and
high percentage
of
our
1990
A.H.
has
Neotropical flora
of the
knowledge
33
GENTRY
come
in the last decade
intensified programs of field work and general collecting.
tend
reach about
to
generally
from the
very different
clear-cut
absence of all of the collections that
Malesian
region
most
metric increase in
collecting activity
have taken
or
we
place,
should be able
tion in nature,
at
least has
make
to
are
of the collections
by gathering
there is
a
where it
seems
very clear
acterized Leiden, the
not
taken
am
related
that
came
where,
name
in
by
a
face
number of cases,
the relevant
clearly recognizable,
being
latex than the other. One had
the other
one
of them had
clearly,
with
as
a
blue
second
petals
species
are
at
consider them
mous
in the
was
one
Rio
one
to
be
Neotropics
Flora
cies
In
a
more
taxa
one
so
objective starting point,
the actual situa-
possible,
same
while
case, two
is
at
lumping
is in the situation
taxonomy. It
can
and
This is the
and
the Flora
preparing
species
a
a
were
must
case
take pre-
of
closely
of
of
Rio
Maquira,
mid-canopy
a
pass the
a
were
One had darker
leaf than
slightly differently shaped
character). Perhaps
always
one
rather
more
telling,
type of Dichorisandra is
small,
erect, with
two
open
Guarea,
were
a
example
much denser inflorescence
a
that has become rather infa-
Rica,
well known in the field
lumped together
In each of these
cases,
it
cases,
to
the
where six
many ecolo-
under Guarea
glabra
seems
very
clear
of sympatry
versa.
as
species
in
a
monographer justified
to me
that
taxonomist's work, it is incumbent
instead of vice
vine
inflorescence, where-
very different plants in the field would
A similar
of
test
same
Moraceae,
tree.
of the variation patterns elsewhere in the range of
a
spe-
Palenque,
identified with the
from the La Selva field station in Costa
fruiting,
that has char-
much work in
especially
forest, but behave as distinct
in the leaf
and
these
conspecific.
comes
to
and
fruits, while the other had glabrous fruits. Very
one,
Palenque
taxonomic solutions,
sympatry.'
overlap
white
complexity
clearly
geo-
not to
seems
At the very least,
degree.
optimal
monographer.
tree, the other
large
some
difficult it may make
that
of
longer petioles
complex. However, in such
much
nize
the
modern, nearly
Neotropics
of the field botanist
exactly the
test
Neotropica monograph.
his decision by
are
in the
ago
that from the
significant
of taxonomic
very distinctive species
looking
who had studied their
recent
as
ecology,
or more
does, and it is in this situation
general,
disservice
problem
different, locally occurring species
gists
have
involved. In another case,
and
and blue flowers. No
ever
in
strongly pubescent
species
two
two
there
(although
two
specialist.
one
not
clearly
very
knowledge
the
'pass
face with this
to
nearly
philosophy
significant
together
words, they
same
as
taxonomists in
Netherlands,
co-occur
the
to
may
that of the herbarium-based
over
taxa
cies. In other
I first
that the
a
or
which
problem
to me
about to describe that the
eminence
place
we now
additional data.
the Flora Malesiana, has done
that I
available. It is
much older and the
taxonomy reflect,
our
decade
a
that has characterized the
While the above kinds of situations may
second kind of
now
are
through greatly
so,
correlated with local
species, often
that would have been reached
ones
or
The conclusions that
no
on
and then work
a
matter
him
out
to
spe-
how
recog-
from that
I have also been
on
been involved in
a
too
much
people,
clear
'right'
but
and
being
two
by
not
together
this
type
when I
problem
dryer
forests than the
The
real
only
to
they
dividuals that have both
have
only
the
most
juvenile
whereas older leaves
grow
glabrous
are
either
these should be
two
entities
regarded
as
two
hairy
uniformly
in
is
one
data,
are
often much easier
will resolve the
field-based
There is
yet
a
we
very
exam-
these
distinguish
of them tends
to
to-
be in
densely white pubescent
the
on
not
and
species
only
it is
possible
in Belize and in the
plant
pubescent
not:
entities,
nonpubescent
at
forms
they (rather slightly)
are
flower
to
dry
completely
different
in Central America. Moreover, the few inleaves
more
the
at
extremes
pubescent
a
or
of the
species
range
that of A. candicans,
uniformly glabrous, just
completely different phenological
I think there would be little
disagreement
that
distinct.
(including sterile collections
obtain), especially when associated with
perceived discrepancies
soluble,
what
have
but
process.
seems
seen
to
perhaps only
This is the
be
case
occurring
if
the
ecological
between the herbarium taxonomist and the
a
considerations
extremely dynamic
in cloud forests
Preliminary
cloud forest ridgetop may have
political
of
speciation taking place
tain cloud forest orchids.
in situ in
evidence
along
nature
situation has been examined
the
in
as
little
of endemic
similarity
or
philoso-
included in the
evolution in
as
that every
suggests
large complement
genetically,
are
action,
for
the base of the Andes. We
very little differentiated from their congeners elsewhere. In the
a
to
third situation, where differences between different taxonomic
be
decision-making
think
the
one.
phies might
example,
to
carefully
a
number of lowland moist for-
a
In this kind of situation I believe that additional collections
which
one
different
two
ecological clue of
specifically
be
additional ramificationof
pubescence approximating
co-occur,
yellow-flow-
out to
to more
throat)
an
Although
that the
together
leaves with
in Central America. Given the
behavior where the
mean
emphatically
and
corolla
individual
same
but these
differentiated,
times of the year where
the
of
recognized by
Whereas in southern Central America this
glabrous.
Most
lumped together?
morphologically
1
good morphological characters (the
together
clearly distinguishes
on
types
are
Arrabidaea chica and A. candicans grow
character is that
Ecuador. Does this
western
material
that illustrates
both grow
other, they
discover both leaf types growing
of
be several very
mentioning.
differentiating
rather minor character very
should be
Volume
years, I have
some
there turned
cases,
pubescence in the
leaf undersurface and the other is
part
all such
example
two
Espirito Santo,
in southern Central America.
gether sympatrically
ests.
nearly
One further
is worth
in
Linhares,
finally got adequate
absence of
species.
as
of
or
at
As in
me.
'wrong':
presence
entities
serratifolia. Specifically,
into Tabebuia
ine the situation, there turned out
best
Special
the other side of this particular situation. For
variability
local
BULLETIN
debate with Brazilian botanists who claim that I have been lumping
ered Tabebuia that grow
as
MALESIANA
FLORA
34
15 years in
slightly
species,
single
most
case
dissimilarity
cer-
isolated
of these
where such
of DNA turned
A.H.
1990
out
to
arisen
land
and
be
as
another character' with
'just
local endemics
the DNA
on
account
sequence.
taxonomist
of
If
slightly
genetic
resolve these
to
one case
very
coriaceous
more
relatedness does
situations,
are
taxonomist's gut feel becomes the only practical
was
isolated on different
populations
tionary
ridge tops
roles' and should therefore be
The easiest solution for
rug and
a
Or
guideline?
tropical biodiversity.
that which is
us
view of the
grappled
diversity,
current
data
it
with
a
openly,
seems
or
Undoubtedly,
and field
to me
can
be
will
albeit
the taxonomic
principle
as
as
that
seems
to me
inevitable in
Bignoniaceae,
in
cataloging
catalogs
to
only
at
great
a
cost
of taxonomic time and
can
be
our
be
a
partial
one.
It
together.
clearly
and
ultimately using
as
well
as
a
scientific
demonstrated to
(and
this bioone to
either
behave,
opinion
between herbarium
Tropics,
seems
that the
key point might
community
that
they expect
find effective
importance
from
well be
by
to
convert-
international outcry about the loss of
this may well become
can
taxonomy
However, it is abundantly clear that the
current
and decision makers the
biodiversity
effort,
taxonomic treatises. In
necessity of providing floristic
political imperative
that
the difference in
in the
if the taxonomic
of
well).
as
the world's
species.
much closer
uncataloged biodiversity
funding agencies
evolu-
practical.
the distinction between the herbarium worker and the field worker
possibility,
that the
sweep the variation under the
responsibility
our
crisis and the
ing the former into the latter. Given the
the
process
understanding, conserving,
to taxa
the 'solution'
brought
to
the general public through
that there is
ecologically,
knowledge
to
biodiversity
basis for
specific recognition
genetically
two
as
species inasmuch
follow with Neotropical
remember
to
the
fulfilling 'unitary
are
in
for the
where the individual
perhaps
on
change
guideline
a
differ-
morpho-
Variation that is
is lost from view, whereas
swept under the rug
makes information available
faunistic)
to
as
may well be
lump problem complexes together (the
However, it also behooves
remove
equivalents
recognized
monographer
many African taxa, and that I used
accord
or
dramatic
a
place
community could (and should?) suggest guidelines drawing
genetic
differentiable
much of
the
at
ancestral low-
switch in flower color
a
hardly
provide
again
same
discernable
no
there
leaves,
not
we
from the
clearly by
endemic taxon,
locally
of Lisianthus that had
species
hummingbird pollination (but
whereas in the other
entiation),
logically
on
with
derivative
two
different cloud forest ridges
differentiatedin
population being
shape associated
35
GENTRY
us.
an
ways
of this
step
increasingly
of
if
viable
impressing
we are
to
upon
produce