Croat T. B., 1994, Taxonomic status of neotropical aroids, Aroideana 17

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THOMAS B. CROAT, 1994 33
Taxonomic Status of Neotropical Araceae
Thomas B. Croat
Missouri Botanical Garden
P.O. Box 299
St. Louis, MO 63166-0299
USA
INTRODUCTION of Araceae in South America is spotty, with
some areas being relatively well known and
The Araceae, with 106 genera and rough others, especially Andean areas of the con
ly 3,200 species is nearly world wide in tinent, being very poorly known. Some ar
distribution. There are two major centers eas for which floristic surveys have been
of species diversity, in tropical Asia and conducted in the past thirty years or so are
tropical America, with nearly an equal num relatively well known. This is especially true
ber of indigenous genera, 43 for Asia and of Venezuela where extensive work has
36 for America (Croat, 1979). Of these to been done, especially by G. S. Bunting
tals 33 are endemic to the American tropics (Bunting, 1975, 1979, 1986, 1988, 1989) but
while 32 are endemic to Asia. Africa, a less also by Croat & Lambert (1986). The Ven
important center of species diversity, has ezuelan flora contains 266 species with an
only 19 indigenous genera with only 12 of additional 25 subspecies or varieties.
them endemic. While the Paleotropics has The Guiana region is relatively well
more genera than the Neotropics (60 versus known at least in part because it is relatively
36) the latter area contains roughly two species-poor rather than because of the ex
thirds the species of the world's Araceae. tent of the collecting effort. Suriname was,
Our level of knowledge of the systematics until recent years, the only part of the
of the neotropical Araceae varies greatly Guianas that received much attention in
from area to area, owing largely to recent regard to Araceae, this largely owing to the
revisionary work or to the interest and area work of Jonker-Verhoef &Jonker (1953) in
concentrated on by particular workers, e.g. Suriname. More recently, the whole region
G. S. Bunting in Mexico (Bunting, 1965) is receiving more attention owing to work
and Venezuela, Croat in Panama and Cen on the "Flora of the Guianas" project and
tral America (Croat, 1978, 1983, 1986a, to the Araceae treatment being carried out
1986b, 1988a, 1991) and Croat & Grayum by Croat and collaborators. In addition,
in Costa Rica. Central America is much more Bunting (in press) has completed the Ar
well known than South America, largely aceae treatment for the Flora of the Vene
owing to the more prolonged effort byaroid zuelan Guyana, the Venezuelan counter
taxonomists in the region, but also owing part of this flora.
to the fact that some parts of the area are Another example of a relatively well
much less rich in species per unit area than known area is the state of Bahia in Brazil
many parts of South America, especially the where Simon Mayo and other members of
species-rich northwestern part of that con the Kew Garden staff, especially R. Harley,
tinent (Croat, 1992). Most of the earlier work have made a number of expeditions. Mayo
in Central America was undertaken by P. C. has also prepared a checklist for Brazil and
Standley in a series of floristic works (Stan any reference to the number of species in
dley, 1927, 1928, 1930, 1933, 1937, 1944). Brazil for any genus discussed in this paper
Species diversity generally increases in relies heavily on his unpublished work.
Central America as one approaches South Mayo has also worked closely with many
America (Croat, 1986a, 1986b). Knowledge Brazilian botanists to encourage their par-
34 AROIDEANA, Vol. 17
ticipation in work with Araceae of Brazil fact that the species inhabiting the Amazon
(see Aroideana for a discussion of these lowlands are in general wide-ranging, often
efforts) . common species. Despite the presence of
Parts of southern South America are by a few endemic species near the mouth of
now also well known, where floristic treat the Amazon, e.g. Philodendron ecordatum
ments for Argentina (Crisci, 1971) and Par Schott, the vast Amazonian region lying be
aguay (Croat & Mount, 1988) have been tween the Atlantic coast and the foothills
completed. In addition, a floristic treatment of the Andes has moderately few, mostly
has been completed for the state of Santa Wide-ranging species. Species diversity in
Catarina (Reitz, 1957). creases dramatically as one approaches the
The published Flora of Peru (Macbride, foothills of the Andes in the west. Species
1936), though falling short of giving an ac occurring on the lowermost slopes of the
curate picture ofthe species count for Peru, Andes tend to range widely in a north-south
does come close to indicating the number direction, often from Colombia to Bolivia
of species actually described for Peru, since, and thus tend not to be endemic. However,
except for Anthurium sect. Pachyneurium some of the species of this region are cur
(Croat, 1991), few groups have had many rently believed to be endemic. The degree
species described from Peru since that pub of endemism increases as elevation increas
lication. A more accurate accounting for the es on the slopes of the Andes and as the
number of species of Araceae in Peru is terrain becomes more dissected with river
published in the "Catalogue of the Flow valleys (Croat, 1994).
ering Plants and Gymnosperms of Peru" To the east of the Amazon basin, es
(Croat, 1993). Though not a thorough re pecially in the Guiana Highlands and in
vision ofthe species occurring in Peru, this eastern Brazil, from the state of Bahia south
list takes into account all species of plants almost to Uruguay, the rate of endemism is
described for Peru as well as all species much higher. Nearly all the species occur
represented only by identified herbarium ring in this region are endemic to eastern
specimens which were able to be verified Brazil, and few range into the Amazon ba
by experts for each family. The checklist sin. For example, five of the eight Anthur
contains 210 species of Araceae for Peru ium species from Santa Catarina are en
but it does not include any unpublished demic to eastern Brazil, including A. acu
names and many species remain to be de tatum N. E. Br., A. gaudichaudianum
scribed. Kunth, A. harrisii (Grah.) Endl., A. lacer
While there is no completed Araceae dae Reitz, and A. pilonense Reitz.
treatment for the flora for Ecuador, a re Though many species have been de
cently published checklist for the Amazo scribed from eastern Brazil, by early aroid
nian lowlands (Renner et al., 1990), which specialists, including Schott, K. Koch, and
lists 92 species of Araceae (a few of them Engler, based on the early collecting efforts
undescribed), gives some indication of the by botanists such as Glaziou, Regel, Riedl,
species diversity of that part of Ecuador. and others, these areas remain poorly
Unfortunately the Amazonian lowlands
known, principally because of the taxo
represent one of the most species-poor por
nomic complexity in such groups as An
tions of the country if its area is taken into
thurium section Urospadix, which domi
account, owing to the widespread nature
nates the area. Perhaps the only group of
of the species in that zone.
aroids well known in the region are mem
The above-mentioned treatments, though
bers of the recently revised Philodendron
regional in nature, help to give an indica
subgenus Meconostigma (Mayo, 1991).
tion of species diversity on the continent
of South America, and any reference to spe The truly temperate parts of the conti
cies counts for any genus is based on them. nent are devoid of aroids, and the subtrop
The lowland Amazon basin is also rela ical portions of the continent, while con
tively well known, principally owing to the taining a number of small, frequently en-
THOMAS B. CROAT, 1994 35
demic genera in the tribe Spathicarpeae, Cauca Department, the department of An
are also relatively species-poor. tioquia, and the department of Cundina
Species diversity is high throughout the marca, especially around Bogota, were well
extent of the South American Andes but collected in the late Nineteenth Century by
especially along the northwestern slope ex collectors such as Lehmann, in time to have
tending from Choco Province in Ecuador, their material included in the revisions of
as well as on both the eastern and western both Schott (1860) and Engler (1905), many
slopes in the Andes in the region of the areas have not been collected until recent
equator and on the eastern slopes of the times.
Andes in Peru. Species diversity is also rel Pichincha Province and a few other areas
atively high in the Cordillera de Merida of of Pacific coastal Ecuador were well col
western Venezuela, but remarkably less so lected by L. Sodiro (1901a, 1901b, 1903a,
in the northern part of the Eastern Cordil 1903b, 1905a, 1905b, 1905c, 1906, 1907,
lera of Colombia and on the entire western 1908) and 257 species (including 281 taxa)
flank of the Eastern Cordillera in Colombia were described. Despite this, the region
(Croat, 1992). Species diversity is also rel remains poorly known, largely because of
atively low in the Central Cordillera of Co the inability to locate and study the widely
lombia. In all cases high species diversity scattered and poorly documented collec
is correlated with high precipitation and tions of Sodiro. Some Sodiro specimens are
with the absence of prolonged dry seasons. deposited in European herbaria (Croat,
Species richness is greatest between sea 1989), but most collections are depOsited
level and middle elevations up to about in the poorly curated herbari um (Q PLS) of
1,500 meters. While some species may range the monastery in Quito where Sodiro orig
up to about 3,750 m (Anthuriurn caucan inally worked. The collections may not be
urn Engl.; Colombia: Antioquia: Villa Ar borrowed and the conditions in the her
teaga, Hodge 7045), diversity drops off dra barium make their study there very difficult
mati cally above 2,000 m elevation. Season (Croat, 1989). Nevertheless, some recent
ally dry areas, such as the central plateau attempts at revisionary work have taken
of eastern Brazil and the lower Amazon ba place in Ecuador in Pichincha Province.
sin, are relatively species-poor, as are the Floristic surveys of the Araceae have been
generally treeless llanos of Venezuela. made of the Reserva ENDESA on the west
Endemism is also especially high in the ern slopes ofVolcan Pichincha. This work,
Andes of western South America, including begun by Jimena Rodriguez de Salvador
the eastern range of the Andes which ex while a student at the Universidad Catolica
tends into Venezuela. Endemism is also in Quito, was subsequently augmented by
high in the Guiana Highlands and in parts investigations of my own, and is nearing
of North America, especially in Mexico and completion and is expected to be pub
in lower Central America, in Costa Rica, and lished in 1995. The paper will be entitled
Panama. For example, Mexico, with 41 taxa Anthllrillln of Reserva ENDESA (Pichincha
of Anthuriurn has 26 endemic taxa. Gua Province , Ecuador).
temala has only three endemic species. Both Other Andean regions are being studied
Honduras and Nicaragua have a single en on a local basis. With the assistance of Jeff
demic species each. Costa Rica has 68 taxa Lake of Grinnell College I have completed
with 22 species endemic, and Panama has a revision of the Araceae for the Flora of La
150 with 82 species, 55 percent of the total, Planada, a natural history reserve in Narino.
considered to be endemic. This revision is also expected to be pub
Because of the high rate of endemism lished soon.
and the very high speciation in many parts With the assistance of another student,
of the Andes, our taxonomic knowledge of Dorothy Bay, I am also working on a revi
all but a few areas of the Andes is very poor. sion of the Araceae of Bajo Calima. This
Although selected areas of the Colombian flora is an exceptionally rich one with many
Andes, such as the region of Popayan in new species, and despite about six separate
36 AROIDEANA, Vol. 17
collecting trips made to this region over the publication of the book, currently
the past ten years it remains still poorly scheduled at Kew during fiscal year 1994.
known. Bay will work on the flora as a part
of a Ph.D. dissertation at St. Louis Univer ALLOSCHEMONE
sity. The project is expected to take three
This genus with two species in tribe Mon
additional years to complete.
stereae is a hemiepiphytic appressed
This has been a general overview of the
climber endemic to the western Amazon
distribution of the neotropical Araceae. The
basin in Brazil and Bolivia. Its placement
remainder of this paper will deal individ
has been somewhat controversial. Madi
ually with different genera to discuss the
son (1976) considered it to be a member of
general level of knowledge of each genus,
the genus Scindapsus, otherwise known
the predicted number of species in each
only from the Old World tropics but later
genus, and what is currently known of their
reestablished it as a distinct genus (Madi
phytogeography. A review of the ecology
son, 1977). It was also treated as a distinct
and life forms of the genera is summarized
genus by Grayum (1990) and Bogner &
in Croat (1988a).
Nicolson (1991). Alloschemone occiden
Discussions of the suprageneric place
talis (Poeppig) Engl. & K. Krause is still
ment of the genera to follow are based on
poorly collected and is known only from a
the latest system of classification, an as yet
few localities (Croat, 1985b). It has been
unpublished work by S. Mayo, ). Bogner,
collected on the Rio Solimoes at Tefe, on
and P. Boyce (in prep.). This work reflects
the Rio Madeira at Humayta, along the Rio
many of the ideas expressed by M. Grayum
Marie, a tributary of the Rio Negro, on the
(1984, 1990) and by Bogner & Nicolson
Rio )apura near Maraa the Department of
(1991). It also takes into account unpub
Pando, province of Frederico Roman along
lished molecular work by French et al. (in
the Rio Negro.
press) on chloroplast DNA and an exten
The genus is still poorly known in many
sive cladistic analysiS of the family by Mayo
respects and living material should be ac
et al. (in prep.). Thus, though perhaps not
quired for additional study.
the final word on the suprageneric classi
fication of the family, it constitutes a con
ANAPHYLLOPSIS
sensus of modern thinking on the classifi
cation of the Araceae. For a discussion of This lasioid genus (tribe Lasieae; sub
all but the most recent revision, including tribe Dracontiinae) of three terrestrial, rhi
that of Hotta (1970) see Croat, 1990. zomatous species is endemic to northern
In order to avoid confusion with names Brazil (Para) and the Guianas. One of the
used in earlier works brief mention should three species, A. americana (Engl.) A. Hay
be made of the major conclusions reached from French Guiana and Surinam, had long
in the work being prepared by Mayo, Bog been considered a Cyrtosperma, but Hay
ner & Boyce. These are as follows: the fam (1988) found that it differs from Asian
ily has been divided into two major groups, members of Cyrtosperma by having fenes
the Protoaroids consisting of subfamilies trate leaf blades, as well as both prophylls
and cataphylls on the rhizome. In addition
Gymnostachyoideae and Orontioideae and
to placing this species into the new genus
the True Araceae, conSisting of subfamilies
Anaphyllopsis, he described two new spe
Calloideae, Pothoideae, Monsteroideae,
cies, A. pinnata A. Hay, from the upper Rio
Lasioideae, and Aroideae. The most signif
Negro in Amazonas State of Brazil, and A.
icant change with earlier systems as out
cururuana A. Hay, from the upper Rio Ta
lined in Croat (1990) is that all genera with
pajos along the Rio Cururu in Para State of
unisexual flowers (previously incorporated Brazil.
variously in Colocasioideae, Philodendro None of the species are particularly well
ideae, and Aroideae) are now included in known and the two most recently described
Aroideae. For further details, one must await are known only from a single collection
THOMAS B. CROAT, 1994 37
each. Certainly more collections should be in synonymy, many regions were poorly
made to determine the true nature of mor collected prior to Schott's or Engler's re
phological variability and geographical visions, and thus have few species de
range. scribed. Interestingly, these same areas, no
Two other species previously thought to tably those along the Pacific slope of west
belong to Cyrtosperma, C. wurdackii Bun ern Colombia, probably are the most spe
ting and C. spruceanum (Schott) Engl., cies-rich. For this reason, substantial
were placed by Hay (1988) in Urospatha numbers of new species exist. In some ar
and Dracontium, respectively. Thus, Cyr eas which have now been well collected,
tosperma is eliminated as a neotropical ge such as the region of the lower Calima River
nus and is restricted to the Asian tropics. basin, a region commonly referred to as
"Bajo Calima," the majority of species ap
pear to be new to science. The region is
ANTHURIUM
largely a transition zone between Tropical
There is now agreement as to the place wetforestand Tropicalforestand has yield
ment of Anthurium in tribe Anthurieae in ed, so far, 133 species including 63 species
subfamily Pothoideae. of Anthurium and 40 species of Philoden
The genus Anthurium is the largest ge dron, with only a few species yet to be de
nus in the family with an estimated 1,000 termined and most appearing to be new to
species. Admittedly, the margin of error in science. The Pacific slope also appears to
counting the number of species in this ge have a high rate of endemism, especially
nus is great. Indeed, the margin of error in between different life zones and at different
estimating the number of species existing elevations. For example, in the department
for Anthurium and Philodendron, the two of Narino, three study sites, all located rel
largest genera in the family, is greater than atively near one another and all located
the total number of all other species in all within a Premontane forest life zone (ac
other neotropical genera combined. While cording to the Colombian life zone map),
the number of species of Anthurium in contained relatively few species which were
Central America (221 spp.) and some parts shared between sites (Croat, 1992).
of South America, e.g. Venezuela (68 spe Probably regions of Tropical forest, which
cies including seven varieties or subspe are restricted to northwestern South Amer
cies), the Guianas, the Amazon basin, and ica, will prove to be the most species-rich
Paraguay, is well known, other areas, es of all. Some parts of this life zone, es
pecially eastern Brazil and the Andean re peciallythe area south of Quibd6, have been
gion of western South America are doubt relatively well collected, but the material
ful. Mayo has produced a checklist for Bra has not yet been analyzed for a determi
zil containing a total of about 100 species, nation of its species diversity.
eight of which are new to science. Still, The situation in Ecuador is even more
owing to the taxonomic uncertainty of many complex regarding exact numbers of spe
species of section Urospadix, a complex cies, especially in Carchi and Esmeraldas
group of species which are difficult to sep Provinces in northwestern Ecuador. Much
arate, the total is likely to be higher than of Ecuador is probably as rich per unit area
that projected by Mayo. as the Pacific slope of Colombia. Both slopes
It is in the Andean region of the conti of the Andes in Central Ecuador in Imba
nent where specific counts of species are bura, Pichincha, Los Rios and Cotopaxi, Bo
most difficult to obtain. While a few areas, livar, Tungurahua, Chimborazo and Canar,
notably, the departments of Antioquia and especially at middle elevations on the Pa
Cundinamarca as well as the region of Po cific slope and at all but the higher eleva
payfm in the department of Cauca, have had tions on the Amazonian slope, are rich in
many species described and probably even species. The same is true of the Amazonian
have a number of species (especially at the slopes of Loja and in the principally low
higher elevations) which must be placed land provinces of the so called "Oriente,"
38 AROIDEANA, Vol. 17
Sucumbios, Napo, Pastaza, Morona-Santia cies to occur. The same is essentially true
go, and Zamora-Chinchipe. Renner et al. for the intermountain valleys in Central
(1990) report 32 species for this region but Peru. Only in the foothills of the Andes on
the actual number is certainly much higher. the eastern slopes do any significant num
Much of the middle elevations of the north ber of species occur but species diversity
eastern slopes of the Andes as well as the here does not come close to matching that
southeastern slopes remain unexplored. in Ecuador. The species occurring there,
Recent surveys of the Cordillera del Con including A. breviscapum Schott, also tend
dor, along the Peruvian border, indicates a to be much more widespread but there are
high rate of endemism. The same is true of also significant centers of species richness
the Serrania de Cutucu further to the north. and endemism such as the areas around
The Amazonian lowlands, though con Tingo Maria in Huanuco Department and
taining some new species, have mostly rath at Tarapoto in San Martin Department.
er wide-ranging species in common with The species distribution in the Amazon
other areas of the Amazon basin. An ex lowlands of Peru mirrors that in the low
ample of the area, now reasonably well col lands of Ecuador, tending to be wide-rang
lected is that of Jatun Sacha which has a ing species, many of which also enter Bra
flora of at least 50 species, including 25 zil. Examples include Anthurium atropur
species of Anthurium. Of this total only pureum R. Schultes & Maguire, A. oxy car
three species are believed to be endemic pum Poeppig, A. lore tense Croat, and A.
to Ecuador. rubrinervium (Link) G. Don.
In contrast to the remainder of Ecuador, The Flora of Peru (Macbride, 1936) is of
the Pacific lowlands of western Ecuador relatively little value. The treatment con
south of Esmeraldas are either mostly de tains 55 species of Anthurium, with eleven
forested or seasonally dry and contain rel names being synonyms of other species
atively few aroid species. This is particu treated and an additional two names of
larly true of the southwestern part of the plants which do not occur in Peru. The re
country in El Oro and Loja. maining names are probably correct, but
The region of northwestern Peru, like that may represent as few as one-third of the
of southeastern Ecuador is relatively dry species in the country. The up to date
with a depauperate aroid flora. Species di checklist for Peru (Croat, 1993) has 76 taxa
versity is substantially greater in the moun but many remain to be described.
tains of northern Peru in the state of Ama Bolivia is relatively poor in Anthurium
zonas, but the region has yet to be well species but has a significant number of en
collected. Most collections existing are the demic species. No aroids occur in the dry
result of University of California anthro eastern portion of the country, but a num
pologist Brent Berlin and his workers who ber of species of Anthurium occur in the
collected in the region of the Rio Cenepa relatively humid intermountain valleys be
and the Rio Santiago. This area is home to ginning in Nor Yungas east of La Paz and
the rare and poorly collected genus Filar extending to the lowlands of Beni and to
um. The drier highland regions of Peru are a lesser extent to the east in Cochabamba.
relatively poor in species. One particularly Paraguay has a depauperate aroid flora
variable species ranging throughout the with only 16 species, including two species
highlands from southern Peru to Central of Anthurium. Argentina has 17 species,
Ecuador is A. dombeyanum Brongn. ex including only one Anthurium, A. para
Schott. The middle elevations are particu guayense Engl. That species ranges north
larly rich in members of Anthurium sect. to Bolivia and southern Brazil. Uruguay and
Pachyneurium (see discussion of this sec Chile have no Anthurium (indeed Chile
tion below). has only the pantropical genus Pistia) and
The entire Pacific coastal region of Peru, Uruguay has only four species in three gen
much like the southwestern part of Ecuador era). In contrast to the northern hemi
is arid, indeed too arid for many aroid spe- sphere where several genera, including Ar-
THOMAS B. CROAT, 1994 39
isaema, Calla, and Lysichiton, range well well represented in Panama with 50 species
north of 45 degrees latitude, few Araceae but has an even greater concentration in
range very far into temperate South Amer northwestern South America, especially in
ica. The southernmost is Pistia, found at 35 the wettest forest types at lower elevations.
degrees latitude in the basin of the Rio de It is particularly well represented in Trop
la Plata near Buenos Aires. ical forest and Tropical Premontane forest
Sections of genus Anthurium are not in Choco Department of Colombia. For ex
equally distributed. The sectional classifi ample, 27 species are already known from
cation discussed here, somewhat modified one small area at Bajo Calima near Bue
from that of either Schott (1860) or Engler naventura in the Department of Valle, in
(1906) is outlined by Croat & Sheffer (1983). transitional zone between Tropical wet
Some sections, such as section Pachy and Pluvial forest.
neurium, are widespread, ranging Relatively few species in the section oc
throughout most of the range of the genus, cur in the Amazon basin. Most of the spe
with the exception of the wettest part of cies in the group are new to science. Be
the range, such as in northwestern Colom cause of their generally similar appearance,
bia. Most members of the section, especial the species are easily overlooked or even
ly series Pachyneurium, are most common mixed up by collectors. Probably no sec
in areas of seasonally dry forest. The center tion has such a high percentage of species
of diversity for sect. Pachyneurium is in new to science, perhaps owing to their in
Ecuador, where 36 species occur, and in conspicuous nature (by aroid standards).
Peru with 28 species. These countries are For example, in Panama, 39 taxa (of a total
also the centers of endemism with 23 and of 80 new taxa described) are members of
13 species respectively. Central America is sect. Porphyrochitonium. The greatest con
a second center of diversity for sect. Pa centration of section Porphyrochitonium is
chyneurium, especially Costa Rica and on the Pacific coast of Colombia, most ap
Panama, with 23 and 22 species (seven and pear to be endemic and undescribed. Schott
five species endemic) respectively (Croat, (1860) described only one member of the
1991). A portion of this section, including section, A. scherzerianum, and Engler
all the cordate species, is restricted to Costa (1906) described only 17 additional spe
Rica and Panama. Another group, series cies while Sodiro (1901a, 1901b, 1902,
Muitinervia, is nearly restricted to Ecuador 1903a, 1903b, 1904, 1905a, 1905b, 1906,
with only a few outlying species occurring 1907, 1908) described only 12 species.
in Colombia (A. carchiense Croat, A. na Though most of the species of section Por
paeum Engl., and A. narinoense Croat) or phyrochitonium described by Engler were
Peru (A. soukuPii Croat and A. ottonis K. included in his section Urospadix, a few
Krause). were included in other sections, including
Section Calomystrium is also wide Tetraspermill1n (A. margaricarpllm Sodi
spread, but with the vast majority of its spe ro) and in Xialophyllium (A. angosturense
cies occurring between Costa Rica, Vene Engl., A. filiforme Engl., and A. tenllinerl'e
zuela, and Peru, especially at middle ele Sodiro). A few species placed in sect. Por
vations on both slopes of the Andes. A sig phyrochitonium in the Central American
nificant percentage of the species, perhaps revision of Anthurium are now believed to
as much as 50 percent is new to science. be aberrant members of sect. Calomys
The percentages of new species are partic trium. This group of species occur in or
ularly high in Panama, with 15 of 18 species along streams and has mostly slender leaves
in the section new to science (Croat, which are not noticeably punctate on the
1986b). The percentages in South America, lower surfaces. The group consists of A.
especially in Colombia where the diversity amnicola Dressler, A. antioquiense Engl.,
is greatest, could be as high or higher. A. antropbyoides Killip, A. rupicola Croat,
Section Porphyrochitonium has a range A. sytsmae Croat, and A. werJlii ined. Croat
similar to that of sect. Calomystrium and is sp. nov. Because of their short internodes
40 AROIDEANA, Vol. 17
and slender leaves they were confused with Central American species of Anthurium in
sect. Porphyrochitonium but breeding general are not closely related to those of
studies have shown that they do not inter South America. For example, of the 221
breed with other members of that section Central American species, only two, A.
but instead breed readily with sect. Calo scandens (Aublet) Engl. and A. gracile
mystrium and are believed to be specially (Rudge) Schott, are truly wide-ranging, i.e.
adapted members of that group_ Perhaps from Mexico to Brazil. While quite a large
they independently evolved slender leaves number enter northern Colombia, or barely
which survive much easier in rapidly mov enter Panama from South America, only ten
ing water. additional species from Middle America
Section Digitinervium is a small group enter into non-Colombian portions of South
with leathery, pli-veined, glandular-punc America (Croat, 1986a).
tate leaf blades and scalariform venation. It Another example pointing out the iso
ranges from Costa Rica to Venezuela and lated nature of Central America is the
Peru, particularly at middle to high eleva breeding behavior of Anthurium sect. Pa
tions. The section is centered in the moun chyneurium. While Central and South
tains of Ecuador, and most species were American species respectively will readily
described by Sodiro (loc. cit.). Only a few interbreed within their own group, few
species exist in this section and relatively Central American species will cross with
few of them are believed to be new to sci South American species (Croat, 1991).
ence. In contrast to those groups mentioned
Section Cardiolonchium is also heavily above, which have the majority of their spe
concentrated in the Andean region at low cies in the Andean regions, section Uros
to middle elevations, especially on the padix is almost exclusively known from
western slopes of the Andes. A few species eastern South America and is most heavily
occur in the lower part of Central America concentrated on slopes of the eroded pla
and one species, A. costatum K. Koch & teau of central and southern Brazil. Here it
Bouche occurs in the coastal range of clearly represents the most dominant grou p
northern Venezuela. One species, A. rub of Araceae. Mayo reports approximately 60
rinervium (Link) Don (probably to in species of sect. Urospadix, and there are
clude both A. polyrrhizum K. Koch & Au numerous new species in the region. Some
gustin and A. aliena tum Schott) is wide members of the section range as far north
spread in the Amazon baSin, ranging from as the Guiana Highlands, and at least one
lowland Ecuador and Peru to the Guianas. member believed to be in the group, A.
Section Cardiolonchium, with frequently lilacinum Bunting, even occurs in the Cor
velvety, often discolored leaf blades, was dillera de la Costa in northern Venezuela.
represented among the earliest introduc Another unique section, Chamaere
tions into European glasshouses. Many spe pium, represented only by A. radicans K.
cies are narrowly restricted and now rare. Koch & Haage, is restricted to eastern Bra
Most have probably already been described zil. Though now represented in cultivated
but a few new species remain. collections in many places, it is apparently
Despite having velvety leaves, a few Mex rare in the wild.
ican species appear to be unrelated to Sec Few groups of Anthurium are restricted
tion Cardiolonchium. They include A. clar to Central America, but one as yet unnamed
inervium Matuda, A. lezamae Matuda, and group possibly deserving sectional status,
A. leuconeurum Lem. These species will represented by plants with cordate, glan
hybridize with other Mexican species in dular-punctate blades, is restricted to Me
cluding species in unrelated groups such soamerica and centered in Mexico. Exam
as A. pedatoradiatum Schott but not with ples include A. lucidum Standley ex
Cardiolonchium species in other areas. This Yuncker, A. chiapasense Standley, and A.
again points out the isolated nature of the verapazense Engl. This group, as well as
Mexican species of Anthurium. Indeed, many other endemic Mexican species, ap-
THOMAS B. CROAT, 1994 41
pears to share little in common with other Peru, with greatest concentrations of spe
species from other parts of Central America. cies in the Andes of Colombia and Ecuador.
The A n thll rill In flora of Costa Rica and Pan· This group probably includes many new
ama, though also highly endemic, at least species. It almost certainly includes two
shows signs of relationships with species disparate groups which will have to be rec
from South America. Most of these species ognized, one represented by A. cuspida
occur in groups which are much better rep tum Master and its allies and the other A.
resented in the Andes of South America. panduriforme Schott and A. corrugatum
The section Polyphyllium, consisting of Sodiro.
two scandent species, A. flexile Schott and Section Belolonchium sensu Schott is al
A. clidemioides Standley, is also restricted most exclusively Andean, occurring pri
to Central America. The group is distin marily in cloud forests at higher elevations
guished by having several internodes be and characterized by the widespread A. pul
tween successive flowering internodes and chrum Engl. which usually is the dominant
in having roots produced along the inter species at elevations above 1,000 m in many
nodes (Croat & Baker, 1978). parts of Ecuador and Colombia. The section
Another largely Central American group also ranges into western Venezuela (e.g. A.
is section Schizoplacium. This small group, berryi Bunting, A. betanianum Croat, A.
with deeply palmately lobed leaves, is ginesii Croat, A. nubicola Bunting, and A.
known primarily from Mexico, the West In signatum K. Koch & Mathieu). Engler's cir
dies (represented there by A. palmatum [L.] cumscription of section Belolonchium was
Don) and northern Venezuela (represent much broader and included many species
ed by A. longissimum Pittier). which occur at lower elevations, even at sea
The section Semaeophyllium (deeply tri level.
lobed blades) is concentrated in southern Section Tetraspermium is widespread,
Central America and in the Andean portion owing to two species, namely A. scandens
of northern South America. Despite previ (Aublet) Eng!. and A. trinerve Miq., but a
ous work by Madison (1978), the group has number of mostly Andean species remain
a number of new species, especially in South undescribed. Most species range from very
America. A new revision of the section is dry areas, such as Tropical dry forest (A.
currently being carried out. pohlii Eng!.) to Tropical moist forest, but a
Section Xialophyllium is an unnatural few species, such as A. scandens ssp. pus
group (Croat & Sheffer, 1983) with at least illum Sheffer and A. lacinosum Sodiro,
two elements. One group, with thin, bul range into Premontane wet forest and Pre
late leaves or at least prominently raised montane rain forest.
tertiary veins, is represented by such spe Another small but widespread section is
cies as A. microspadix Schott, A. colum Dactylophyllium, a group with palmately
bianum Engl., and A. myosuroides (Kunth) compound blades. It ranges throughout
Endl. Another group, with more coria most of the range of the genus (except in
ceous, smooth leaves is represented by such Paraguay and Argentina) and is most abun
species as A. mindense Sodiro, A. sarmen dant in regions of Tropical mOistforest. The
tosa Engl., and A. popayanense Engl. Sec section is most diverse in eastern South
tion Xialophyllium is primarily Andean but America and in the Amazon basin. It is rep
ranges from Mexico to Bolivia with the resented by such species as A. eminens
greatest concentration at middle to high Schott, A. 'pentaphyllum (Aublet) Don and
elevations in the Andes of Colombia, Ec A. clavigerum Poeppig. A few species from
uador, and Peru. This group probably con eastern South America may be new to sci
tains a number of new species. ence.
Other primarily Andean groups are sec A well known but insignificant group is
tions Polyneurium and Belolonchium. Sec Leptanthurium. It is represented by A.
tion Polyneurium ranges from Nicaragua gracile (Rudge) Schott, one of the most
to the mountains of western Venezuela and widespread species in the genus. This is
42 AROIDEANA, Vol. 17
the only Anthurium species with a chro Aroideae, occurring usually as understory
mosome base number of 10 and is believed plants, from near sea level to 2,300 meters.
to be unrelated to any described and the The genus Asterostigma consists of only
section is not closely related to any other six species, all but a few of them rather
section. A few additional undescribed An poorly known. Those in the Andes, such as
dean species probably also belong here, A. integrifolium Madison and A. pavonii
but their chromosomes have not yet been Schott, occur in cool mountain valleys, of
studied. ten on steep slopes. Only the latter occurs
Two monotypic sections are very geo in Peru. Asterostigma riedelianum (Schott)
graphically isolated. Section Chamaere Kuntze is endemic to the state of Bahia in
pium with a single species, A. radicans eastern Brazil, while A. tweedianum Schott
Koch & Haage occurs in eastern Brazil while is endemic to Santa Catarina in southeast
A. gymnopus Griseb. in section Gymno ern Brazil. Asterostigma luschnathianum
podium is endemic to Cuba. Neither group Schott is known from Minas Gerais and Rio
appears to have any close relatives. de Janiero states, and A. lividum (Lodd.)
A large number of Anthurium species re Engl. is the most widespread species, rang
main unclassified as to section. Species in ing from Minas Gerais to Rio Grande do
volved mostly consist of larger cordate SuI.
leaved species which clearly do not belong Collecting Asterostigma poses no partic
in any ofthe other described cordate groups, ular problem, although they are not com
e. g. Cardiolonchium, Calomystrium, Po mon, and few species have been well col·
lyneurium, or Belolonchium. Probably sev lected. Recollections are necessary, es
eral small sections will have to be created pecially of the Brazilian species to recon
to accommodate them. Engler placed most firm Engler's treatment.
of such species known to him in section Another problem with Asterostigma con
Belolonchium. Another somewhat smaller cerns the name A. cubense (A. Rich.) K.
group which does not fit into any recog Krause ex Bogner, purportedly from Cuba
nized section includes more or less oblong (Bogner, 1969). The species is related to
to lanceolate-leaved plants lacking glan A. riedelianum 0. Bogner, pers. comm.).
dular punctations, e.g. A. michelii Guillau This name is based on a mixed collection
min. Both groups contain new species. with Xanthosoma cubense (Schott) Engl.
Future work on Anthurium must con Although Asterostigma has never been col
centrate in two areas: the Andean countries, lected in Cuba and is probably restricted
especially Colombia, Ecuador, and Peru as to southern South America, the true nature
well as in eastern Brazil. The problems in of A. cllbense has, in my opinion, never
these two areas are very different. In eastern been determined.
Brazil the majority ofthe species have been
described but are still poorly defined and
BOGNERA
little understood. They are very similar to
one another, and the type localities are very This monotypic genus (tribe Dieffenba
much degraded. Some species may be lost chieae), represented by B. recondita (Mad
altogether. ison) Mayo & Nicolson, is known only from
In the Andes of western South America the western part of the state of Amazonas
species diversity is much higher, and there on the Rio Javari. Madison (1980) initially
are many undescribed or poorly known described it as a species of Ulearum. Since
species. A great deal of time and space will it is in cultivation at the Munich Botanical
be needed just to sort out the specimens Garden and elsewhere, it is now quite well
to determine how many species there are. known. It is very similar to Dieffenba
chieae, according to J. Bogner (pers.
ASTEROSTIGMA comm.). The tribe Dieffenbachieae is
This is a genus of terrestrial, tuberous placed in the Dielfenbachia Alliance in
herbs in tribe Spathicarpeae of subfamily subfamily Aroideae. Little remains to be